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61 Cards in this Set

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  • Back
Define innate immunity.
Innate: nonspecific immunity -a set of disease-resistance mechanisms that are not specific for a particular pathogen
Give characteristics of innate immunity.
1. Pre-exists infection or exposure to foreign antigen

2. Response occurs immediately after recognition of foreign organisms or substance

3. Does not confer protection against subsequent exposure to the same pathogen or foreign antigen
Define Adaptive immunity.
specific immunity, displays a high degree of specificity as well as the property of memory
Give characteristics of adaptive immunity.
1. Does not pre-exist initial exposure to a specific pathogen of foreign antigen

2. Requires 6-7 days to develop after initial exposure.

3. Confers memory - host is protected from subsequent exposure to the same organism

4. Secondary response is very rapid and effective
What is the first line of defense just after the host's exposure to a pathogen?
Innate immunity... most organisms are cleared by the non-specific innate immune response

Failure to clear an organism results in triggering of an acquired immune response
Innate immunity is composed of how many defensive barriers?
What are the defensive barriers of innate immunity?
1. Anatomic barriers - prevent entry of pathogens
-- Skin (outer epidermal layer and inner dermal layer)
-- Mucous membranes

Physiological Barriers - temperature, pH, and chemical mediators

Phagocytic barriers - ingestion of extracellular particulate material by phagocytosis

Inflammatory Barriers - tissue damage causes an inflammatory response
What are two types of anatomical barriers?
Skin - outer epidermal layer and inner dermal layer

Mucous Membranes
Describe the dermis and epidermis.
Epidermis - comprised of dead skin cells and keratin

Dermis - connective tissue, blood vessels, hair follicles, sebaceous glands, and sweat glands
Describe the sebaceious glands
produce oily substance called sebum and sebum contains lactice acid and fatty acids that inhibit bacterial growth
What are the physiological barriers?
Chemical mediators
Describe how temperature acts as a physiological barrier?
normal body temp inhibits grown of some microorganisms

fever response inhibits growth of pathogens
Describe how pH acts as a physiological barrier.
Low pH - the gastric secretions in the stomach maintain a low pH that kills most ingested organisms - skin also maintained at a low pH
What are chemical mediators?
1. complement: killing of microbes, opsonization of microbes, recruitment and activation of leukocytes.

2. mannose-binding lectin: opsonization of microbes, activation of complement

3. C-reactive protein: opsonization of microbes, activation of complement

4. Coagulation factors: walling off of infected tissues

5. Lysozyme: hydrolytic enzyme found in saliva and tears that cleaves the peptidoglycan layer of the bacterial cell wall

6. Interferon: group of proteins (cytokines) produced by virus-infected cells that induce an anti-viral state in adjacent cells and activates leukocytes
Phagocytosis is primarily mediated by?
neutrophils and macrophages that respond to the presence of an invading microorganism
What cells are the first cells to reach sites of inflammation? What cells are the second to reach?

Neutrophils vs. macrophages: which cells are longer lived?
Macrophages are longer lived and have the ability to replicate and therefore play an important role in innate defense after the initial insult
Describe the steps in phagocytosis.
Cell's plasma membrane expands around particulate matter to form large vesicles called phagosomes, which fuse with lysosomes to form phagolysosomes where the ingested material is destroyed.
What are the different types of inflammatory barriers?
1. Vasodilation

2. Increased capillary permeability

3. Influx of phagocytic cells
What are the 2 types of adaptive immune responses?
Humoral immunity
Cellular immunity
What is humoral immunity?
immunity mediated by molecules in the blood called antibodies that are produced by B lymphocytes... specifically plasma cells

Abs recognize microbial antigens, neutralize the infectivity of microbes and target microbes for destruction.
What type of immunity is the principle defense against extracellular microbes and their toxins?
Humoral immunity
What immunglobins promote phagocytosis?
What immunoglobins promote the release of inflammatory mediators from leukocytes?
What is cell mediated immunity?
mediated by cells called T lymphocytes

promotes the destruction of cells harboring intracellular pathogens
What is the difference between active and passive immunity?
Active immunity is induced by exposure of the host to a foreign antigen - the host's immune system plays an active role in responding to the antigen
-- confers specificity
-- confers memory
-- is not immediate

Passive immunity - conferred upon the individual by transferring serum or lymphocytes from a specifically immunized person - person becomes immune w/o having been exposed to or having responded to antigen
-- confers resistance rapidly w/o having to wait for active response (6-7days)
-- confers specifity
-- does NOT confer memory
What is the difference between passive humoral immunity and passive cell mediated immunity?
Passive humoral - transferred by cell-free, Ab-containing protions of the blood--serum or plasma

Passive cell mediated - trasnferred with cells (T cells)
What are the features of the adaptive immune response?
1. Specificity
2. Memory
3. Diversity
4. Specialization
5. Self - limitation
6. Nonreactivity to self
Describe B lymphocytes.
B cells specifically recognize antigens by virtue of expressing unique antigen receptors on their surface -- membrane immunoglobulin

BCR - 2 heavy chains and 2 light chain polypeptides that are disulfided together

Binding of antigen to BCR leads to cell activation and entry into cell cycle
What terminal end will you find the antigen binding sites?
BCR = divalent

amino end
Describe T lymphocytes.
T cells express unique antigen receptors on surface that are comprised of 2 polypeptides (alpha and beta) that are disulfide linked

TCR recognizes antigen that is bound to either MHCI or MHCII

Have helper and cytotoxic T cells
What is the difference between CD8 and CD4 T cells?
Cd8 = cytotoxic, MHCI, recognize endogenous peptides

CD4= helper, MHCII, recognize exogenous sources
Describe the action of helper T cells.
Activation of helper T cells in response to antigen leads to proliferation and secretion of cytokines that promote activation of B cells and other T cells
What is the difference between helper TH1 and TH2.
TH1 = produce cytokines which support inflammation

TH2 = produce cytokines which promote B cell activation and development of immune responses that depend on Ab production
Describe the function of cytotoxic T cells.
Activation of cytotoxic T cells leads to proliferation and differentiation into cells that exhibit cytolytic activity
What are the three types of APCs?
B cell
dendritic cells

These are MHC2 cells
Describe the function of APC?
APC first internalize antrigen either by endocytosis or phagocytosis, then process the antigen and display it on their surface bound to MHC Class II, which is recognized by the TCR on the helper T cell.
What cells constitute the largest portion of WBCs that are circulating in the blood at any given time - most WBCs produced everyday are these subset?
Do neutrophils die after they phagocytiza bacteria? macrophages?
Neutrophils phagocytize bacteria and destroy them, killing themselves in the process.

Macrophages phagocytize bacteria and then present parts of the bacteria back out on their cell surface to communicate with (or induce) cells of the adaptive immune response.
Where do macrophages come from?
WBCs that circulate through the blood as immature monocytes and also migrate from the blood into challenged tissue and then differentiate into macrophages
The local imnflammatory response is often mediated by a set of cytokines... name the cytokines.
IL-1; IL-6; TNF-alpha
If the cytokines are in high enough amounts, it can create a systemic response... describe the systemic response.
1. increased temp
2. feedback on liver - produce more acute phase reactants (CRP, MBL, serum amyloid A (SAA), complement

3. feedback on bone marrow - bone marrow is site of hematopoiesis - increases the production of neutrophils in acute manner
What are the 3 main players of the adaptive immune response?
T cells
B cells
Humoral immunity mainly deals with....
extracellular microbes, parasites, and neutralizing toxins
Describe the sequence of events in humoral immunity.
Helper T cells produce cytokines which activate B cells.

B cells are the precursors to terminally differentiated plasma cells which secrete SOLUBLE proteins called Abs

Abs are the effectors in humoral response
Cell mediated immunity mainly deals with...
virally infected cells or cells containing intracellular bacteria
Describe the sequence of events in cell mediated immunity.
Helper T cells produce cytokines which can also differentiate cytotoxic precursor cells into cytotoxic T cells
What is a major difference between cell mediated and humoral responses?
Cell mediated - effector is a cell - T cell

Humoral - effector is a soluble protein = Ab
What is agammaglobulinemia?
Patients that have no B cells. Therefore, they have no Ab and must be given IV antibodies.
Describe the antigen receptor found on B cells.
the membrane immunoglublin has 2 heavy and 2 light chains joined by a disulfide bond.
What are the two types of receptors found on T cells? Which one is more common?
alpha-beta -- more common
T cell receptors only recognize.....?
peptides either in the context of MHC2 or MHC1
All cells on your body express which MHC class?
When is bradykinin released and what does it cause?
It is released when you have physical insult to the skin.

It causes an increase in vascular permeability and vasculat dilation
What is the role of fibrinopeptides?
Acts as chemoattractant to attract phagocytic cells and
What do each of the following receptors bind to and what is their fxn?

Mannose binding lectin
C-reactive protein
LPS binding protein
Complement - binds to microbial cell wall components

Mannose - recognizes mannose on microbes - human mannose is always glycosylated by microbes isnt

C-reactive protein - bind to phosphatidylcholine in microbial membranes

LPS - recognizes lipopolysaccharide which is part of gram negative cell wall

each causes opsonization of microbes and activation of complement
What does opsonization of microbes actually do?
It puts a signal on the microbe surface that allows the phagocytic cells to more effectively bind to that microbe
What is the lectin pathway in regards to the complement pathway?
involves a situation where you have mannose binding lectin or c-reactive protein binding to a bacterium. This triggers the complement cascade
What is the Alternative Pathway in regards to the complement cascade?
A C3 component of complement would bind to the surface of a gram negative bacterium which provides an activating surfaces which allows the alternative pathway to be triggered
What is the Classical Pathway in regards to the complement cascade?
Ab molecules either IgM or certain isotopes of IgG bind to the surface of a bacterium and triggers the cascade
What is C3a and C5a?
Fragments of products of the complement cascade which are NAPHLOTOXINS

These bind to receptors on mast cells and cause mast cell degranulation. This causes factors to be released that increase vasodilation and increased vascular permeability

They are also chemotactic factors and promote recruitment of neutrophils to the site of the inflammatory response