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334 Cards in this Set
- Front
- Back
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What are portals of entry for microbials in the human body?
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- nose
- mouth - skin - sex - eyes |
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what are examples of viruses that can infect the respiratory tract?
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- rhinoviruses (cause colds
- myxoviruses (cause flu) |
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what ar examples of bacteria that can infect the respiratory tract?
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- bordetella pertusis
- heamophilus influenza - streptococcus pneumoniae - streptococcus pyogenes - neisseria menengitidis |
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what are examples of fungi that can infect the respiratory tract?
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- candida albicans
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how do diseases primarly enter the mouth?
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through contaminated food or water
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what are examples of waterborne bacteria?
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- vibrio cholerae
- E. coli - giardia |
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what are examples of foodborne bacteria?
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- salmonella
- E. coli - staphylococcus aureas - vibrio cholerae - shigella |
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how are ways that microbes can enter through the skin?
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- some bacteria use enzymes to get through
- some worms burrow through - abrasions and punctures can be portals of entry |
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what are examples of ticks or insects that can infect the skin?
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- ticks (borrelia brugdorferi) cause lyme disease
- Anopheles mosquitoes (Plasmodium) cause malaria - Tse Tse fly (T. gambiense) causes sleeping sickness |
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how do insects and ticks cause microbes to enter through skin?
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they serve as vectors to introduce pathogens through skin
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what are examples of objects causing microbes to enter through skin?
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- rusty nail punctures (clostridium tetani) causes tetanus
- Contaminated needle pricks (HIV) causes AIDS |
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what are examples of animal bites that cause microbes to enter through skin?
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- dog bite (rhabdoviruses) causes rabbis
- human bite: many bacteria and viruses found in the mouth and saliva |
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what are examples of organisms that can enter the body through sex?
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- Treponema pallidum causes syphilis
- neisseria gonorrhea causes gonorrhea - HIV causes AIDS - herpes virus causes herpes |
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what is the covering that protects the eyes?
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- Conjuctiva
- this is the outer covering of the eye - its a barrier, but some bacteria can bind to it |
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what are examples of microbes entering the body through the eyes?
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- haemophilus aegyptius causes pinkeye
- chlamydia trachomatis causes trachoma - herpes simplex virus (can enter through injury to eye) - acanthamoeba caused by dirty contact lenses |
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what are portal of exits in the human body?
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- nose
- gastrointestinal tract - sex |
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what are examples of organisms that can exit through the respiratory tract?
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- airborne: yersina pestis causes bubonic plague
- Touch: rhinoviruses cause common colds |
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what are examples of organisms that exit through the gastrointestinal tract?
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- feces: vibrio cholerae causes cholera
- shigella/salmonella causes dysentery/diarrhea - poliovirus causes polio |
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what are examples of organisms that can exit through the body during sex?
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- treponema pallidum causes syphilis
- neisseria gonorrhea causes gonorrhea - HIV causes AIDS - chlamydia trachomatis causes trachoma - herpes viruses cause herpes |
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what are adherence factors?
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- aka adhesions
- found on the surface of bacteria and used to stick to tissues and for attachment |
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what are examples of some bacterial parts that can be considered adherence factors?
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- fimbriae
- spikes - flagella and hooks |
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how are fimbriae used as adhesion?
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- these are used to attach to urogential mucosal epithelial cells
- used by organisms like N. gonorrheae |
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how are spikes used as adhesion?
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- used for attachment to host cell receptors
- found in many viruses |
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how are flagella and hooks used as adhesion?
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- binds to their host cell
- found in many organisms |
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what are examples of some virulence factors?
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- adherence factors
- capsules - enzymes - toxins |
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what are capsule glycocalyx?
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- bacteria can produce slimy molecules primarily made of carbs
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what are capsules made of?
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- they are heat labile structures
- made of polysaccharide and/or proteins |
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what are capsules used for?
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- used to prevent phagocytosis by macrophages and PMN's
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what are examples of bacteria that produce capsules?
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- streptococcus pneumoniae
- yersinia pestis - klebssiella pnemoniae - haemophilus influenzae |
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what do s. mutans produce and why?
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- produce dextran
- this helps it to bind to teeth to produce plaque |
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what are examples of enzymes that act as virulence factors?
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- coagulase
- kinases - hyaluronidase - DNase - hemolysins |
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what is coagulase?
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- produced by staphylococcus aureus
- capable of clotting serum - converts fibrinogen to fibrin (thus plasma clots) - may contribute to pathogenesis by inhibiting phagocytosis |
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what are kinases?
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- capable of breaking blood clots
- strepkinase and staphylokinase are proteases that convert plasminogen to plasmin - this dissolves clots and promotes bacterial spread |
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what is hyaluronidase?
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- produced by streptococci and staphylococci
- known as spreading factor - breaks down ground substance of connective tissue |
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what is DNase?
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- produced by some streptococci and staphylococci
- degrades DNA - thick pus contains viscous DNA released from dead phagocytes |
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what are hemolysins?
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- enzymes that are able to break red blood cells
- enchances bacterial spread by breaking blood clots - some can lyse cells |
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what are examples of hemoysins that can lyse cells?
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- S. pyogenes streptolysin "O"
- "S" release cytoplasmic granules in leukocytes resulting in cell lysis |
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what are toxins?
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they are poisons produced by bacteria and fungi
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what is the most detrimental virulence factor?
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toxins
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what are the two major groups that toxins are divided into?
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- endotoxins
- exotoxins |
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what are endotoxins?
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- these are toxins that are part of the cell walls
- they are a major cause of death in hospitals - they induce fever by releasing pyrogens |
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what is an example of an endotoxin?
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- LPS
- LPS is part of the cell wall of gram negative bacteria - the lipid A component of LPS is toxic |
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what are exotoxins?
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- great majority of toxins and very important to humans
- released during growth and metabolism - soluble proteins - predominately produced by gram positive bacteria - very immunogenic |
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which are more toxic - exotoxins or endotoxins?
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generally exotoxins are
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what are the 3 types of exotoxins?
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- enterotoxins
- neurotoxins - cytotoxins |
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what are enterotoxins?
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these are toxins that act in the intestinal tract
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what are examples of enterotoxins?
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- cholera toxin
- E. Coli toxin |
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what does the cholera toxin do?
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(produced by vibrio cholerae)
- increases cAMP - the increase in cAMP results in severe diarrhea |
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what does the E. coli toxin do?
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(produced by e. coli)
- increases cAMP - causes travelers diarrhea |
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what are cytotoxins?
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- toxins that act on the cells or tissues
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what is an example of a cytotoxin?
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- diphtheria toxin
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what does the diphtheria toxin do?
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(produced by corynibacterium diphtheriae)
- toxin coded by a bacteriophage that is found in C. diphtheriae - inhibits protein synthesis |
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what are neurotoxins?
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- toxins that act on the nervous system
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what are examples of neurotoxins?
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- botulism toxin
- tetanus toxin |
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what does the botulism toxin do?
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(produced by clostridium botulinum)
- inhibits release of acetalcholine - results in paralysis - extremely powerful and minute amounts of it will result in death of patient |
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what does the tetanus toxin do?
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(produced by clostridium tetani)
- known as lockjaw disease - binds to neural gangliosides and blocks glycine release - this inhibits nerve impulses to one muscle while the opposing muscle is contracting |
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what are examples of staphylococcus aureus exotoxins?
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- hyaluronidase
- catalase - exfoliative toxin - staphylokinase |
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what does hyaluronidase toxin do?
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- break hyaluronic acid and helps spread bacteria
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what does the catalase toxin do?
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breaks H2O2 ---> H2O + O2
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what does the exfoliative toxin do?
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- causes intradermal tissue speration
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what does the staphylokinase toxin do?
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- dissolves fibrin clots, allowing bacteria to spread
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what are enterotoxin E and F?
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- these toxins are powerful
- normally acquired from contaminated foods - result in severe cramps, diarrhea, and vomiting - cause staphylococcus food poisoning |
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what is TSS-I toxin?
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- causes toxic shock syndrome
- in past, has been associated with tampon use |
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what is impetigo?
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- caused by staphylococcus aureus
- causes epidermal swelling and usually break and peel away |
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what are cutaneous infections?
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- caused by staphylococcus aureus
- example would be funcles (boils) that are abscesses resulting inflammation of a hair follicle or sabaccous gland |
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what is the best defense for non-specific microbes?
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- uncompromised (unbroken) skin
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how is uncompromised skin a protection from non-specific microbes?
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- its tightly packed, so acts as a barrier
- low pH of skin inhibits bacterial growth - oily substances from sebaceous glands inhibit most bacterial and fungal growth - salts from sweat act as antimicrobial |
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what are examples of serious pathogens that can enter through broken skin?
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- clostridium perfringenes causes gas gangrene
- clostridium tetani causes tetanus - rhabdorviruses cause rabies - plasmodium causes malaria |
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what are the 3 classifications of the 3 defense lines incase bacteria gains access to tissues?
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- first line of defense
- second line of defense - third line of defense |
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what is the first line of defense?
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- hair
- mucous - tear (lysozyme) - cilia |
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what is the second line of defense?
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- phagocytosis
- inflammation - complement fixation |
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what is the third line of defense?
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- humoral immunity
- T-cell mediated immunity |
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how does normal flora help protect the body?
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- by competing with pathogenic bacteria for available nutrients
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what can decrease normal flora?
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- antibiotic treatment
- other health reason (person then susceptible to infections like candida albicanas |
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what are the body's primary host defenses?
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- mucous
- stomach acid and enzymes - ear wax - cleansing action |
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how does mucous protect the body?
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- traps microorganisms
- contains lysozyme that hydrolyses the peptiodglycan layer of bacteria |
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where are lysozymes located?
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- mucous
- tears - saliva |
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how does stomach acid and enzymes protect the body?
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- HCl in the stomach kill bacteria
- enzymes in intestine and stomach discourage bacterial growth |
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how does ear wax protect the body?
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- traps microorganisms and prevents infections
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what are the cleansing actions that protect the body?
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- flow of urine
- eyeball washing by tears - secretion of vaginal fluids - vomiting |
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what is phagocytosis?
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process of engulfing of foreign or large particles into vesicles
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what are organisms that can phagocytose pathogens?
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- macrophages (also act in processing presentation of antigens to T-cells)
- neutrophils - polymorphonuclear leukocytes, PMN's |
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what are the stages of phagocytosis?
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- chemotaxis
- formation of phagosome - formation of phagolysosome - destruction of pathogen - removal of debris |
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what is inflammation?
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- powerful non-specific defense mechanism
- almost every day occuring |
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what does inflammation happen in response to?
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- injury
- irritation - microbial infections - heat - radiation |
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what are the key hallmarks of inflammation?
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- dilation
- increased blood vessel permeability |
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what does inflammation produce?
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- edema (swelling)
- erythema (reddening - heat (enhances phagocytosis and bacterial growth) - pain |
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what are the effects from the chemicals released from the inflamed tissue and complement derived peptides?
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- increased diapedesis and phagocytosis
- elevation of temperature by pyrogen, which enchances phagocytosis and reduces bacterial growth - basophils and mast cells release mediators |
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what are the mediators that basophils and mast cells release during inflammation?
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- histamine
- serotonin - prostaglandins - bradikinins |
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what do the basophil and mast cell mediators act as?
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- act as vasodialators and increase vessel permeability
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what does inflammation increase?
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- phagocytosis
- diapedesis |
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where can the complement system be directed?
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- specific or non-specific antigens
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what is the complement system composed of?
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- 20 blood proteins working in a cascade to lyse cellular antigens and neutralize viruses
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where are complement proteins made?
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- in the liver hepatocytes, lymphocytes, and monocytes
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what does the complement system enhance and mediate?
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- enhances phagocytosis
- mediates tissue inflammation |
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what are the two pathways for the complement system?
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- the classical pathway
- the alternate pathway |
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what does the classical pathway require?
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- presence of antibodies (IgM or IgG)
- classical component protein |
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what is the cascade order for the classical pathway?
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C1
C4 C2 C3 C5 C6 C7 C8 C9 |
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how is the classical system initiated?
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- when IgM or IgG antibodies bind to a membrane of an antigen
- components of C1, C4, C2 act as initiation and magnification phases |
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what kind of pathway is the classical pathway?
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- fast and very effective pathway in lysing cellular antigens
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what are the steps in the classical pathway?
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- recognition of antigens by IgM or IgG
- activation of C1q and formation activated complex C1qrs - follwed by enzymatic activation of C4, C2, C3 and C5 by breaking each protein to "a" and "b" sub-units - C4a, C2a, C3a, and C5a sub-units are released to the surrounding - "b" sub-units bind and form the membrane complex - Once C5 binds to the membrane attack complex, then C6, C7, C8, C9 bind and cell lysis occurs |
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what is the activation of the alternate pathway?
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can be activated by:
- complex bacterial - fungal -plant polysaccharides - C-reactive protein -tumors - C3i *DOESN'T REQUIRE ANTIBODIES |
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what are the complement components required in the alternate pathway?
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- factors B, D, P (properdin)
- C3, C5, C6, C7, C8, C9 |
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where are complement proteins made?
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- in the liver hepatocytes, lymphocytes, and monocytes
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what does the complement system enhance and mediate?
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- enhances phagocytosis
- mediates tissue inflammation |
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what are the two pathways for the complement system?
|
- the classical pathway
- the alternate pathway |
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what does the classical pathway require?
|
- presence of antibodies (IgM or IgG)
- classical component protein |
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what is the cascade order for the classical pathway?
|
C1
C4 C2 C3 C5 C6 C7 C8 C9 |
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how is the classical system initiated?
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- when IgM or IgG antibodies bind to a membrane of an antigen
- components of C1, C4, C2 act as initiation and magnification phases |
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what kind of pathway is the classical pathway?
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- fast and very effective pathway in lysing cellular antigens
|
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what are the steps in the classical pathway?
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- recognition of antigens by IgM or IgG
- activation of C1q and formation activated complex C1qrs - follwed by enzymatic activation of C4, C2, C3 and C5 by breaking each protein to "a" and "b" sub-units - C4a, C2a, C3a, and C5a sub-units are released to the surrounding - "b" sub-units bind and form the membrane complex - Once C5 binds to the membrane attack complex, then C6, C7, C8, C9 bind and cell lysis occurs |
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what is the activation of the alternate pathway?
|
can be activated by:
- complex bacterial - fungal -plant polysaccharides - C-reactive protein -tumors - C3i *DOESN'T REQUIRE ANTIBODIES |
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what are the complement components required in the alternate pathway?
|
- factors B, D, P (properdin)
- C3, C5, C6, C7, C8, C9 |
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what acts in the initiation and magnification of the alternate pathway?
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- C3b and magnesium
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what is the alternate pathway like?
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- slower and less specific than the classical pathway
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what is the cascase of the alternate pathway?
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- C3 occasionally is activated producing C3i
-Factor B binds to C3i producing C3iB complex - C3iB then converts C3 ---> C3a ad C3b; and C3b binds to targe cell - followed by binding of factor B to C3B bound on the membrane producing C3bB complex - Factor D further cleaves C3bBb and then properdin binds and makes the complex stable on the membrane - C3bBb acts as a C3 convertase and further splits C3 ---> C3a and C3b - C3B binds ---> C3bBb properdin complex giving C3bBbC3b, which acts as C5 convertase - from this point the process proceeds as the classical complement pathway |
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what are the functions of the complement system?
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- Enhances phagocytosis by opsonization
- Mediates lysis of cellular antigens. - Neutralizes viruses. - Enhances inflammatory responses |
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what is the function of the C3a componment of the complement system?
|
- is a potent petide which causes release of histamine from mast cells.
- Mediates vasodialation, increases capillary permeability - Enhances chemotaxis of phagocytes and inflammation |
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whats the function of C2a, C3a, C4a and C5a of the complement system?
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- function as cytotoxins and stimulate inflammation
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whats the function of C3a and C5a of the complement system?
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- are powerful anaphylotoxins
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what are the two types of specific immunity?
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- humoral immunity
- cell mediated immunity |
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what is thehumoral immunity mediated by?
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- mediated by B-cells (plasma cells)
- plasma cells secrete antibodies |
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what is cell mediated immunity mediated by?
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- primarly T cells
- natural killer (NK-cells) - killer cells (K-cells) |
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what are the two types of immunity?
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- inherent immunity (natural resistance to diseases)
- acquired immunity |
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what are the two sub-types of acquired immunity?
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- active immunity (developed by host)
- passive immunity (not developed by host) |
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what are the two sub-types of active immunity?
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- natural (infections)
- artificial (vaccines) |
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what are the the sub-types of passive immunity?
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- natural (mother to fetus)
- artifical (use of immune serum) |
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how are macrophages involved in specific immunity?
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- detect invading antigens, process and present them to T-cells
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how are t-cells involved in specific immunity?
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- produced cytokines that regulate the immune system
- some directly participate in specific immunity |
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how are cytokines involved in specific immunity?
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- activate B-cells and the activated B-cells differentiate to plasma cells, which produces the antibodies
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what are antigens?
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- molecules (mostly proteins) that are capable oto elicit antibody response
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what are the types of molecules that can be antigens?
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- proteins
- nucleic acids - lipoproteins - glycoproteins - complex carbs |
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what is antibody?
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- a protein, or neutralizing immunoglobulin, which is produced in response to an antigen
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what is hapten?
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- a low molecular weight substance that cannot elicit an antibody on its own but will if bound to a larger molecule
|
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how much molecular weight should a molecule have to act as an antigen?
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about 10,000 MW
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what are stem cells?
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progenitors of all the immune cells
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where are stem cells found?
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- in the bone marrow
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what cells are orginated from stem cells?
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- granulocytes
- mononuclear leukocytes - others |
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which granulocytes are originated from stem cells?
|
- basophils ( about 0.5%)
- eosinophils (about 1-3%) - neutrophils (about 55-90% |
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which mononuclear leukocytes are originated from stem cells?
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- monocytes (about 3-7%)
- lymphocytes (about 20-35%) |
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which "others" are originated from stem cells?
|
- erythrocytes
- platlets |
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where are basophils found?
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- in blood and contain large granules
|
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what are basophils known as when they enter a specific tissue?
|
they are then knows as mast cells
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where are mast cells found?
|
- in aereolar tissue along blood vessels, mucous membranes, lungs and gastrointestinal tract
|
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what do mast cells secrete?
|
- histamine
- seratonin - heparin |
|
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what is the function of mast cells?
|
- when secreted hormones, they cause vasodilation during inflammation at the site of infection and causes constriction of lungs
- also involved in immediate hypersensitivity reactions |
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what are neutrophils?
|
- PMN's
- they are the first white blood cells to arrive at the site of infection |
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what is the primary function of neutrophils?
|
- phagocytosis
|
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what do neutrophils contain?
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- digestive enzymes and other chemicals used to degrade substances
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how many PMN's are in circulation?
|
about 25 billion
|
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what is the lifespan of a neutrophil?
|
- about 8 days
|
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what do eosinophils contain?
|
- peroxidase and digestive enzymes
|
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what are eosinophils involved in?
|
- allergic reactions
- destruction of parasitic worms and fungi |
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where do monocytes originate?
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- in the bone marrow
|
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whats the largest white blood cells?
|
monocytes (macrophages)
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wht are monocytes called after they differentiate?
|
- after differeentiation monocytes become macrophages
|
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what do macrophages secrete?
|
- many cytokines (IL-1, TNF)
|
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what is the function of macrophages?
|
- their secretion is involved in assisting, inhibiting, or mediating immune reactions
- act as cellular house keepers mopping up messes created by infection and inflammation - Macrophages are phagocytic and are able to process and present partially digested antigens in association with MHC (class I or class II) molecules to B-cells and T-helper cells. |
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what are dendritic cells?
|
- they are a different type of cell that processes antigens to lymphocytes
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where do platelets (thrombocytes) originate?
|
- bone marrow, from giant multinucleate cell called megakaryocyte
|
|
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what does the megakaryocyte cell break into?
|
- irregular shaped pieces and bits of cytoplasm and nucleus
|
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what are platelets involved in?
|
- blood clotting
- releasing chemicals for inflammation reactions |
|
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where do red blood cells originate?
|
- bone marrow
|
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what is the function of red blood cells?
|
- to carry oxygen and carbon dioxide
|
|
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what can red blood cells be a target of?
|
- can be a target of immune reactiions
ex. transfusion of wrong blood type |
|
|
what are the lymphoid organs?
|
- thymus gland
- lymph nodes - spleen - lymphatic vessels - bone marrow - tonsil |
|
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what is the thymus gland?
|
- a lymphoid organ where T-cells mature
- it exhibits a high rate of activity and growth until puberty and then starts to shrink in size |
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what happens if the thymus is removed in neonates?
|
- severe immunodeficiency
|
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what happens if the thymus is removed in adults?
|
- its not as severe since adults have developed enough T-cells
|
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where are lymph nodes located?
|
- along the lymphatic channels and blood vessels
|
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where does major aggregations of lymph nodes occur?
|
- under the armpit
- groin - neck |
|
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where does the initial encounter between lymphocytes and microbes occur?
|
- occur in the lymph nodes
|
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what are lymph nodes used for?
|
- as filtering materials
|
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what is the spleen?
|
- organ with similar structure and function as the lymph nodes
|
|
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does the blood circulate in the spleen or lymph nodes?
|
- in the spleen
|
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what cells are located in the spleen?
|
- B-cells
- T-cells - macrophages |
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what happens if the spleen is removed in children?
|
- severe immunodeficiency
|
|
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what happens if the spleen is removed in adults?
|
- doesn't affect their immunity too drastically
|
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what are some other lymphoid tissues?
|
- tonsils
- breasts - intestinal tract |
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where are the tonsils located?
|
- in the pharynx
|
|
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what are the tonsils for?
|
- to provide active lymphocytes
|
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in pregnant and lactating women, what do breast act as?
|
- act as temporary sites of antibody - producing lymphoid tissues
|
|
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what parts of the intestinal tract function against intestinal pathogens?
|
- appendix
- lacteals (lymphatic vessels) - peyer's patches |
|
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which cells are known as lymphcytes?
|
- B and T-cells
|
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where do B and T-cells originate and mature?
|
- in primary lymphoid organs (bone marrow and thymus)
- originate in the bone marrow - mature in the thymus |
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where do lymphocytes migrate after maturing?
|
- to specific areas of secondary lymphoid organs (nodes, spleen)
|
|
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whats the function of lymphocytes?
|
- key for specific immunity
- work in close association with macrophages |
|
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where do B-cells originate and mature?
|
- in the bone marrow
|
|
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what do differentiated B-cells (plasma cells) produce?
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- produce specific antibodies
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what is the function of B-cells?
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- they have membrane bound IgM and IgD antibodies
- involved in humoral immunity (antibody production) - in few instances, they are able to process antigens and present the processed antigens to T-cells, leading to their activation |
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how does B-cell activation happen
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- may be in a T-cell dependent of T-cell independent manner
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what do pre-committed B-cells (with specific clonal specificity) do?
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- they bind to antigen via membrane bound antibodies or presented by macrophages
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what happens in T-cell dependent B-cell activation?
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- cytokines produced by macrophages and T-cells activate B-cells
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what do activated B-cells do?
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- they divide by mitosis to generate a large number of geneticlly identical daughter cells
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what do the daughter cells that B-cells generate end up becoming?
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- some become plasma
- others become memory cells |
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how much antibodies can plasma secrete?
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- 2000 per second
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what are memory cells stored for?
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- for a quick response in a subsequent same antigen response
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how many antibodies does each activated B-cell produce?
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- only one type of antibody thats able to bind to the antigen it was produced for
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how does antigen-antibody binding work?
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- its very specific
- the eliciting antigen binds to the antigen binding site of the antibody - this is similar to enzyme-substrate binding characteristics |
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where is the antigen binding site?
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- in the hypervariable region of the antibody
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what are cross reactive antibodies?
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- this happens in some cases with antigen-antibody binding
- happens when the eliciting antigen has a close structural similarity to other antigens |
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what are the five classes of antibodies (immunoglobulins)?
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- IgM
- IgA - IgD - IgE - IgG |
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what is a typical antibody composed of?
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- 2 light chains
- 2 heavy chains |
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what is the MW of IgM?
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1,200,000
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what is the first antibody produced in response to antigen?
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- IgM
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is IgM a pentamer or monomer?
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- can be both
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what % of serum antibody does IgM constitute for?
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5-10%
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where is IgM found?
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- in membranes of B-cells
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what is IgM involved in?
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- agglutination
- precipitation - compliment fixation - phagocytosis |
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what is the MW of IgG?
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- 150,000
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which antibody is the major antibody?
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IgG
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what % of serum antibody does IgG constitute for?
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80-90%
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is IgG a pentamer or monomer?
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- mainly found as a monomer, but can be dimer
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what is IgG involved in?
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- agglutination
- precipitation - compliment fixation - phagocytosis - can also cross to the placenta and protect fetus - also found in breast milk |
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what is the MW of IgA?
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160,000
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is IgA a monomer, pentamer, or dimer?
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- mainly monomer
- present in secretions in the body's inner mucosal surfaces as a dimer |
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whats the MW of IgD?
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- 180,000
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where is IgD found?
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- on the membrane of B-cells
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what is IgD involved in?
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- B-cell activation
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what is the MW of IgE?
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- 190,000
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is IgE a monomer, pentamer, or dimer?
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- normally found in trace amounts as monomer
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what is IgE involved in?
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- involved in allergic reactions
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what do the CD's do?
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- CD2: promotes adhension between T-cells or their target cells
- CD3: helps transduce signal when Ag-MCH complex binds to TCR - CD4: promotes adhesion to APC B-cells probably binding to MCH - CD5: promotes adhension vius infected cells probably binding to MHC I |
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what does LFA-1 do?
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- promotes cell-cell adhesion
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which antibodies activate the classical complement system?
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- IgG and IgM
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how can antibodies enhance phagocytosis?
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- by opsonization (coating the antigen with antibody)
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can antibodies affect viruses?
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- yes, by neutralizing them and making them non-pathogenic
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what does the production of cytokines from t-cells do?
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- activates and regulates the immune system
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what do suppressor t-cells do?
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- involved in suppression and modulation of the immune system
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what do cytotoxic T-cells do?
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- kill virus infected and tumor cells
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what are the 3 main types of T-cells?
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- T-helper cells (Cd4)
- T-cytotoxic cells (CD8) - T-suppressor cells (CD8) |
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what are mature T-cells capable of recognizing difference between?
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- self
- non-self |
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what are substances that are recognized as non-self?
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- immunogenic
(sometimes even self antigens can be seen as non-self, in which case they too will be attacked as if they were foreign antigens |
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what do T-helper (CD4) cells do?
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either by direct contact or production of cytokines:
- help B-cells to recognize the antigens - help other T-cells to recognize antigens - constitute 65% of T-cell population |
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what do T-cytotoxic cells (CD8) do?
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- recognize endogenously produced antigens and kill target cells
- activated T-cytotoxic cells deliver cytokines to attack the target cell membrane and kill it by apoptosis |
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what cells do T-cytotoxic cells kill when they produce their antigens?
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- fungi
- protozoa - mycobacteria - cancer cells - virus-infected cells - grafted cells |
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what do T-suppressor cells (CD8) do?
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- used to restrict uncontrolled immune responses
- regulate production of antibodies |
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what are delayed hypersensitivity T cells (Td)?
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- cells involved in some delayed responses to antigens
ex. tuberculin, contact dermatitis, due to poison ivy or poison oak |
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what are Killer (K) and Natural killer (NK) cells?
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- immune cells found in the blood, spleen, and lungs
- able to kill tumor cells and virus infected cells |
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how do T-cells function in a different manner than B-cells?
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- The T-cells act in direct contact with the antigen, whereas the B-cells produce antibodies that react with the antigen
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how does activation of T-cells happen?
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- when they react with processed antigens presented by antigen presenting cells such as macrophages and dendritic cells
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what do the T-cells do once they're activated?
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- they differentiate to one of the subsets (T-helper, T-cytotoxic, or delayed hypersensitivity T-cells)
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what types of cells can activated T-cells become?
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- either effector cells or memory cells
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how long do memory cells live?
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- up to 70 years
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how many genes do lymphocytes use to produce large number of specific receptors?
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- about 500 genes
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what is the clonal selection theory?
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- states that undifferentiated lymphocytes undergo genetic mutations and recombinations as they proliferate in the embryo and create large variations
( this is explaining how lympocytes create the variety of specific receptors) |
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what is the ultimate genetic variation?
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- is to create variation in the amino acid sequences in the T-cell receptors, hence, the shape and specificity of the T-cell receptor will be different for each lymphocyte clone
- theoretically, this will give about a billion clones of lymphocytes |
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what are some plasma proteins?
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- antibodies
- complement proteins - kinins - clotting factors |
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what are antibodies?
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- proteins secreted by plasma cells
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what are complement proteins?
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- set of about 20 proteins that are used in specific and non-specific immunity
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what are kinins?
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- peptides derived from kininogens and serum proteins
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what are the functions of kinins?
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- induce vasodilatation
- increase permeability of blood vessels at site of infection - act as chemoattractants for macrophages - stimulate pain receptors |
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what are clotting factors?
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- plasma proteins which work in a cascade to form blood clots
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what are some types of cytokines?
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- cytokines
- interferons - tumor necrosis factor - lymphotoxins - perforins |
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what are cytokines?
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- proteins produced by B-cells, T-cells, and macrophages which are used in specific immunity
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what are interferons?
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- proteins like y-interferon and B-interferon, which are used to inhibit viral replication
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what are tumor necrosis factor?
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- this is a cytokine used to kill tumors and activate leukocytes to kill bacteria
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what are lymphotoxins?
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- these kill cells by fragmenting DNA
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what are perforins?
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- proteins that are aable to introduce holes on membranes of target cells, leading to lysis of the target cells
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how does the immune system act under normal conditions?
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- its well coordinated and recognizes difference between self and non-self
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what happens when an immune system goes wrong?
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- can promote diseases rather than prevent them
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what are hypersensitivities?
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- when the immune system goes wrong and we get an autoimmune disease
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what are the 4 types of hypersensitivites?
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- Type I: Immediate (< 30 min)
- Type II: Cytotoxic (5-12 hr) - Type III: Immune-complex (3-8 hr) - Type IV: Cell-mediated (24-48 hr) |
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what is Type I hypersensitivity?
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- immediate adverse reaction in response to a presensitized exogenous antigen
- this allergy is also known as atopic anaphylaxis - there may be a genetic component to this type - this type can last over a lifetime, can be outgrown, or can develop suddenly |
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what are examples of Type I allergins?
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- hay fever
- pollen - dust - mold spores - animal hair - formalin - drugs |
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what is atopic anaphylaxis?
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- chronic local allergy like hay fever or asthma
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what are examples of cytokines that basophils and mast cells have?
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- histamine
- seratonin - leukotrines - platelet activating factor - prostaglandings - bradikinins |
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where do the cytokines mediate increase?
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- in the capillary permeability
- dilation - mucous secretion - smooth muscle constriction |
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where do the cytokines mediate decrease?
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- in the central nervous system activity
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each mast cell carries how many IgE binding sites?
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- 30,000 - 100,000
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what leads to degranulation?
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- IgE bridged by an antigen leads to degranulation
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what does degranulation of mast cells release?
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- cytokines that cause rashes, itching, redness, sneezing, tears, and diarrhea
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what are some allergies that occur as a result of drugs?
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- sodium metabisulfite (sulfite)
- tetrazine yellow dye - monosodium glutamate - penicillin, sulfa drugs, and aspirin |
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what is sodium metabisulfite?
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- its added to wine and vegetables as a preservative
- some people become allergic to this and have asthma-like attacks as well as anaphylaxis |
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what is tetrazine yellow dye?
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- added as a colorant to foods and tablets
- can cause asthma, rhinitis, and hives |
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what is monosodium glutamate?
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- a flavor enhancer
- can cause burning sensation, tightness and numbness in chest and neck |
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when can penicillin, sulfa drugs, and aspirin be allergins?
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- can be allergins when processed by the liver and release haptinic molecules
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what are some treatments of allergens?
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- avoidance of allergen
- corticosteroids - cromolyn - antihistamines, aspirin, epinephrine, theophylline |
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how do corticosteroids help treat allergens?
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- keep the plasma cell from synthesizing IgE and inhibit T cells
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how does cromolyn help treat allergens?
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- acts on the surface of mast cell; no degranulation
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how do antihistamines, aspirin, epinephrine help treat allergens?
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- counteract the effects of cytokines on targets
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what is type II hypersensitivity triggered by?
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- IgG or IgM bound to target cells, which leads to complete fixation and cell lysis
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whats an example of type II hypersensitivity?
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- destruction of the red blood cells in a wrong blood transfusion
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what does anti-Rh antibody production result from?
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- from transfusions of unmatched Rh
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what happens if the father is Rh+ and mother is Rh-?
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- if the child is Rh+ then, this will lead to Erythroblastosis fatalis, which results in a massive lysis of red blood cells of the fetus by maternal anti-Rh+ antibodies
- usually occurs in the second pregnancy as a result of a presensitized mother |
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what does type III hypersensitivity involve?
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- involves excess Ag-Ab complexes not phagositozed by macrophages deposited in basal membranes or epithelial cells
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what doe the free floating Ag-Ab complexes in type III do?
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- they can be deposited in tissues or organs, creating an immune complex reaction, which triggers complement fixation and inflammation
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what are examples of type III hypersensitivity?
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- Arthus
- serum sickness - glomerulonephritis |
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what is arthus?
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- localized immune complex reaction formed in the vicinity of repeated antigen injection in rabbits
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what is serum sickness?
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- injection of horse IgG to humans which results in fever, itchy rashes, and swollen painful joints
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what is glomerulonephritis?
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- immune complex reaction that damages the glomeruli
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what is type IV hypersensitivity?
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- mediated by T-cells
- commonly known as delayed-type hypersensitivity |
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what do the reactions of type IV hypersensitivity result from?
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- result from migration of macrophages and T-cells to an infection site in a pre-sensitized host
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what can type IV hypersensitivity be due to?
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- infectious agents
- contact dermatitis - graft rejection |
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what is an example of the "infectious agents" for type IV hypersensitivity?
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- best example of this is the tuberculosis skin test which is known as the tuberculin test (PPD)
- other similar tests include leprosy, syphilis, histoplasmosis, toxoplasmosis, and candidiasis |
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what is type III hypersensitivity mediated by?
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- mediated by Td class of T-cells which release cytokines that increase the inflammatory reaction leading to swelling
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what is contact dermatitis?
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- common types are caused by contact with poison oak, poison ivy, cosmetics and metals in jewelry (mostly nickel)
- also exposure to latex |
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what does allergic contact dermatitis arise due to?
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- due to haptens that combine with proteins in the skin
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what is the immune system supposed to react to and be tolerant to?
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- react to: foreign antigens
- tolerate to: self antigens |
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what is autoimmunity?
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- this is what happens in some instances when people can develop immunity against self
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how does autoimmunity happen?
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- in most cases it is not clear why tolerance to self is lost
- may be due to loss of T-suppressors or viral infections |
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what is systemic lupus erythematosus?
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- patient produces antibodies to many organs and tissues (kidneys, bone marrow, skin, joints, muscles etc)
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what happens with rheumatoid arthritis condition?
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- autoantibodies (IgM) against other antibodies will be deposited and bind to synovial membrane of the joints and activate macrophages to release cytokines
- inflammation will result and destruction of tissue and joint will occur |
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what is multiple sclerosis?
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- paralyzing neuromuscular disease with lesions in the insulating myelin sheath that surrounds neurons in the white matter of the central nervous system
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what is multiple sclerosis caused by?
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- autoantibodies and T-cells
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what is myasthenia gravis?
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- neuromuscular autoimmunity which arises due to autoantibodies to acetalcholine receptor
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what does myasthenia gravis affect?
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- affects skeletal muscles
- first ones to be felt are muscles of the eye and throat - eventually can progress to complete skeletal muscle function loss resulting in death |
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what results when the pancreas is targeted by autoantibodies?
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- type I diabetes
- type II diabetes |
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what is type I diabetes?
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- insulin dependent
- results because of autoantibodies and T-cells that destroy the insulin-producing cells |
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what is type II diabetes?
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- non-insulin dependent
- when sufficient insulin is produced but the cellular receptors available for insulin are few |
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what can cause type II diabetes?
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- reduction of the insulin receptors may be due to autoantibodies that compete for the available receptors
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what do agglutination reactions occur as a result of?
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- result of cross-linking antibodies called agglutinins, which bind to agglutinogens and form visible clumps
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what are some common tests that use the agglutination tests as diagnostic tests?
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- determining blood types
- rapid plasma reagin (RPR) is used to test for presence of antibodies to syphilis - cold agglutinin, run at 4-20 degrees, is used to diagnose Mycoplasma pneumonia |
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what are some latex agglutination tests that are commonly used for diagnostic purposes?
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- pregnancy hormone in urine
- yeast and bacteria such as Staphylococci, streptococci, and gonococci - rheumatoid arthritis |
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what type of test is available to diagnose certain viral diseases?
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- viral agglutination tests
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what is used to perform viral agglutination tests?
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- red blood cells that naturally react with viral antigens
- to perform these tests, red blood cells and known viruses and the test serum are added |
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how is the viral agglutination test read?
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- if no agglutination: positive
- if agglutination occurs: means the patient serum doesn't have antibodies, therefore the virus has reacted with the red blood cells and agglutinates them |
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what do precipitation reactions occur as a result of?
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- as a result of soluble antigens known as precipitogen that react with antibodies and precipitate forming an insoluble substances
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where are precipitation reaction tests used?
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- in veneral disease research Lab (VDRL)
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what are common dyes that are used in diagnostic tests?
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- fluroescein isothiothionate
- rodamine |
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what are the two methods for the fluorescent antibody test?
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- direct method
- indirect method |
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what happens in the direct method for the fluorescent antibody test?
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- a primary antibody labeled with a dye is used and then examined with a fluorescent microscope
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what happens in the in-direct method for the fluorescent antibody test?
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- in this method, the antigen is bound to the antibody
- then a fluorescent dye labeled secondary antibody is added and examined with a fluorescent microscope |
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the fluorescent antibody test is commonly used to diagnose which diseases?
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- syphilis
- strep throat - lyme disease |
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what is the ELISA test?
|
- this is also known as enzyme immunoassay (EIA)
- |
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what is done in the ELISA test?
|
= in this assay an enzyme-antibody complex is used as indicator for the reactions that may occur
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what are the enzymes that are commonly used in the ELISA test?
|
- horse radish peroxidase
- alkaline phosphatase |
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what do the enzymes in the ELISA test release?
|
- both enzymes release a chromogen when they are exposed to their substrate
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ELISA test can be run in a ______ or _______ way.
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direct ; indirect
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what is the procedure for the direct method for the ELISA test?
|
- The antibody is adsorbed on an ELISA well.
- The test antigen is added which will bind to the adsorbed antibody. - An antibody linked to an enzyme is added. This will sandwich the antigen. -A substrate to the bound enzyme is added. In a positive test color change will occur. |
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for the ELISA test, which method, direct or indirect, is more sensitive?
|
the indirect method
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what is procedure for the indirect method for the ELISA test?
|
- The antigen is adsorbed on an ELISA well.
- The test sample is added. If an antibody is present it will bind to the adsorbed antigen. - An enzyme linked secondary antibody (e.g. goat antihuman IgG) is added. If the test sample had an antibody, the enzyme linked secondary antibody will bind to the primary antibody. - A substrate to the bound substrate is added. If the secondary antibody is bound a color change will occur. |
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what does the western blot test test for?
|
- the presence of antibodies in a test sample
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what is the procedure for the western blot test?
|
- Test strips are prepared by electrophoresing the test antigen.
-The test strips containing the antigen of interest are incubated with a test serum. -The test strips are then developed using a radioactive or colorimetric label. - The test sample is then compared with a positive control. |
