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321 Cards in this Set
- Front
- Back
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Epithelial cells exhibit what hair-like structure on their surface? |
Cilia
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What antimicrobial molecules do epithelial cells secrete?
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defensins
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What is TcR? |
T cell receptor |
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What cells secrete mucus |
goblet cells |
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What is the use of mucus |
- trap microbes - prevents adhesions |
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What are the 3 key players of the innate immune system |
mast cells, tissue resident macrophages, dendritic cells |
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How are mast cells, macrophages and dendritic cells distributed? |
embedded through virtually all tissues form an immunological early warning system mast cells near vessels |
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A mast cells granular appearance is caused by what? |
granules are bags full of potent substances such as: - histamine - leukotrine B4 (LTB4) - cytokines such as TNF alpha - cheekiness such as CXCL2 |
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Why is rapid reaction of mast cell degranulation important + how is it achieved. |
How - pre-synthesis of the antimicrobial molecules Why - fast response to pathogens |
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Histamines + LTB4 cause what effect to nearby blood vessels |
Vasodilation to increase blood flow to area - more leukocytes in the region to combat infection Increased permeability of vessels - for white blood cells and fluid to leave. |
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What cell is the first responders to the mast cells signal? |
neutrophils |
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What are the steps of the trans-endothelial migration |
1. Rolling 2. Firm Adhesion 3. Trans-migration |
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What happens in the rolling phase of transendothelial migration
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weak interactions between neutrophil and endothelial cell results in a slow rolling motion along the surface |
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What happens in the firm adhesion phase of transendothelial migration |
the cytokine action upon the endothelial cell produces upregulation of proteins. These proteins have a stronger interaction with the neutrophils causing them to come to a stop |
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What happens in the transmigration phase of trans-endothelial migration |
the neutrophils follow chemotactic gradient and squeeze between the cells of the endothelial cells. |
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Three signs of immune reaction are yellow tinged flesh, redness and swelling. What causes this? |
Yellow - myeloperoxidase (anti-bacterial) and pus from neutrophils Redness - vasodilation Swelling - leaky vessels |
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What is the difference of prevalence of neutrophils in humans compared to mice. Why is this important? |
50-70% of circulating leukocytes in humans 10-25% in mice Mice are the key model organism for immunology |
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What is significant about the nucleus of the neutrophil? |
trilobed / segmented |
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What are the three tools that neutrophils can use in an infection? |
1. degranulation 2. phagocytosis 3. netosis |
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What is released from neutrophils in degranulation? |
nucleotides, bioactive amines, bioactive ions, adhesion molecules, PMPs, kinocidins, mitogenic factors, coagulation factors, protease inhibitors, proteases and glycosidases |
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What are the basic steps of phagocytosis |
bacterium binds to receptor on cell cell surface membrane extends and surrounds the pathogen by fusing together. pathogen encased in phagosome phagosome fuses with lysosome pathogen dies neutrophil apoptoses |
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What is netosis |
Netosis is the process of self destruction of the neutrophil to destroy pathogens |
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How does netosis kill pathogens |
neutrophils "explode" their DNA and granules DNA gets coated with antimicrobial enzymes as exploded when hits pathogens they are in turn coated with antimicrobial proteins |
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What are the three granulocytes |
eosinophils basophils neutrophils |
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What is the precursor to macrophages and dendritic cells? |
monocytes |
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What causes neutrophils to exit a vessel in the same direction? |
chemotactic gradient |
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What two type of cells can secrete cytokines? |
stromal cells & immune cells |
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What behaviours do cytokines affect? |
life span motility killing capacity repair programmes proliferation |
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What is meant by cytokine "cross talk" |
cytokines work in many directions simultaneously creating an interactive network |
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What is a chemokine? |
chemotactic cytokine |
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What is a PAMP |
pathogen associated molecular patterns |
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What does TLR1 & TLR2 detect? |
lipoprotein, unconventional LPS, bacterial |
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what does TLR 2 detect? |
peptidoglycan |
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What does TLR 2 & TLR 6 detect |
mycoplasmal lipoprotein |
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What does TLR 4 detect? |
enterobacterial LPS |
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What does TLR 5 detect? |
flagellin |
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What does TLR 11 detect? |
profilin (protozoa)
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What does TLR3 detect? |
dsRNA - viral |
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What does TLR7 detect? |
ssRNA - viral |
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What does TLR8 detect? |
ssRNA - viral |
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What does TLR9 detect? |
CpG DNA (bacterial) |
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What does DAMP stand for? |
damage associated molecular patterns |
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TLR 9 detects what DAMP |
genomic and mitochondrial DNA |
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What DAMPs do TLR 4 and TLR 2 detect? |
histones |
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Define innate immunity |
non-specific |
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How can we tell that innate immunity is conserved? |
it is found in plants, fungi, insects |
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Describe the physical properties of defensins |
Small Cysteine Rich Cationic |
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What produces defensins |
Epithelial cells |
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How do defensins harm pathogens |
integrate into microbial membrane group disrupt memrane form pores |
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What is complement |
biochemical cascade that clears pathogens |
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Are complement proteins active or inactive in blood? |
inactive |
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Where are complement proteins activated? |
bacterial surface |
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What processes can complement cause? |
chemotaxis MAC opsonisation |
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What is MAC |
membrane attack complex |
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What is an anaphylatoxin |
the smaller "a" consituents cleaved from proteins during complement signalling molecule |
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What form of complement is part of the adaptive immune system? |
classical pathway |
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How do innate cells detect PAMPs? |
Pattern Recognition Receptors (PRRs) |
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What is the difference between external PRRs and internal PRRs? |
internal ones detect intracellular viruses |
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Recognition of a PAMP by a PRR will cause what? |
activation mediator release inflammation |
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How did Toll Like Receptors get their name? |
Drosophila irradiated and lost Toll gene Unable to synthesis receptor Over run with fungal infection |
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Give an example of TLR in plants. What does it detect? |
FLS2 in arabidopsis thaliana flagellin sensitive 2 |
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What enables TLR 2 to detect peptidoglycan and TLR 5 to detect flagellin |
both PDG and flagellin are made of repeat monomers, the individual monomer triggers the response |
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After detection of PAMP by the TLR what is the cascade of proteins that follow? |
MyD88 IRAK TRAF6 NF-kappaB |
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The cascade of proteins after PAMP detection by the TLR will lead to an increase of what in the nucleus? |
transcription factors |
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Increases of transcription factors in the nucleus after PAMP detection by TLRs leads to increase production of what? |
cytokines |
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How does inflammation control itself? |
with the initial response healing of injury and tissue repair is also initiated |
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What proteins in particular are upregulated during the emmigration of leukocytes from blood to tissues |
ICAM-1 |
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What does ICAM-1 stand for? |
Inter cellular adhesion molecule 1 |
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What proteins on leukocytes stick to ICAM-1 on endothelial walls? |
integrins |
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What is the name for leukocytes moving across the epithelium? |
diapedesis |
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How do leukocytes penetrate the basement membrane during emigration from blood to tissues |
proteolytic enzymes |
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What is the mechanism of chemotaxis
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2. First contacts with chemokine on one side of cell. 3. Receptors triggered 4. Cytoskeleton reorganizes which polarizes cell to move in that direction. 5. Reinforced by further receptor hits |
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Complement C5a, N-formyl methionine, arachidonic acid metabolites are all examples of what?
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Chemokines |
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How does inflammation induce it's own resolution?
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1. Short half life of cytokine mRNA and protein 2. pro-inflammatory cytokines induce cortisol to inhibit their own production 3. IL-1Ra and sTNFR interfere with IL-1 and TNF 4. IL-4 and IL-10 down regulates TNF, IL-1, IL-8 but upregulates IL-1RA |
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What are the two types of inflammation?
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acute and chronic |
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What's the difference between acute and chronic inflammation?
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A = short duration, protein exudate, neutrophils predominate C = long duration, macrophages and lymphocytes, few neutrophils |
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What can cause chronic inflammation
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repeated attempts at healing cause progressive fibrosis |
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What percentage of lymphocytes are T cells |
70% |
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What % of T cells are alpha-beta T cells |
95 |
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Aside from alpha beta T cells, what is the other group called?
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gamma delta |
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What are T cells called before they have recognised an antigen? |
naive |
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What two processes occur once a T cell has been activated? |
clonal expansion (proliferation) and differentiation |
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What has to happen to an antigen before a T cell can recognise it? |
- phagocytosed by antigen presenting cell - processed and cleaved into short peptides - presented on APC surface with a MHC molecule |
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What is the name for the receptor on a T cell that recognises an antigen presented on a APC? |
T Cell Receptor |
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The two external "processes" from a TcR bind to different things, what does each part bind to |
1 to the MHC 1 to the peptide |
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How many amino acids are involved between an antigen on a APC and a TcR? |
1 or 2
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Is the bond between a TcR and an antigen on a APC weak or strong? |
Weak |
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What can you say are the two general functions of costimulatory molecules? |
- induce intracellular response - form a stronger bond between T cell and APC |
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What is the name for the structure that forms around the TcR when it binds to the antigen and MHC on the APC? |
immune synapse |
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What adhesion molecules can form the immune synapse? |
ICAM-1 LFA-1 |
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true or false Costimulatory molecules are specific to one antigen? |
FALSE |
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true or false Costimulatory molecules are invariant from cell to cell |
TRUE |
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What two costimulatory molecules are present on EVERY T cell? |
CD3 CD28 |
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How many proteins form the complex that is CD3? |
5 |
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What structure on the T cell is the CD3 costimulatory molecule attached to? |
TcR
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What happens to the CD3 costimulatory molecules once TcR binds to an antigen? |
long cytoplasmic tails bind + activate tyrosine kinases initiate intracellular signalling |
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Which MHC class do CD4+ cells bind to? |
MHC 2
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Does the CD8 or CD4 bind to the MHC at the same place as the peptide or a different place? |
Different |
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What is the function of CD4? |
increases binding between APC and T cells links to Lck enzyme |
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Once attached to the Lck enzyme, what does CD8 or CD4 on a T cell do? |
drags Lck enzyme to CD3 so CD3 can begin to recruit signalling enzymes within the T cell |
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What class of MHC do CD8+ cells bind to? |
class 1
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CD8, like CD4 also increases binding to the APC and links the Lck enzyme. True or false?
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TRUE |
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CD8+ cells are what kind of T cell? |
Cytotoxic T cells |
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CD4+ cells are what kind of T cell? |
Helper T cells |
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What costimulatory molecules form the secondary immune synapse? |
CD28 ON THE T CELL CD80/86 ON THE APC |
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CD 28 is only present on certain T cells? True or False |
False Present on ALL |
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Ligation between CD28 and CD80 triggers what additional sequence within the T cell? |
signals essential for IL2 transcription |
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Which costimulatory molecules are responsible for stronger binding between the T cell and APC? |
CD4 + CD8 |
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Which costimulatory molecules are responsible for forming an intracellular response? How does each do it? |
CD3 - tyrosine kinase activation on cytoplasmic tail CD4 + CD8 - link to Lck enzyme to CD3 - recruit further signalling enzymes CD28 - IL2 transcription |
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Which interleukin is associated with autocrine signalling in the helper T cell, the absence of which would leave to tolerance? |
IL 2 |
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After recognition of the antigen-peptide complex on the APC by the T cell, both IL2 and it's receptor are expressed. What does this trigger? |
clonal expansion |
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If a CD4+ cell which had recognised it's specific antigen but had costimulatory molcules, what would be the outcome |
tolerance to the antigen |
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After clonal expansion CD40ligand affects the T cell. What is the effect and what other molecules are involved? |
OX40 ICOS differentiation |
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What is the only cell that can process and present an antigen capable of activating a T helper cell? |
Dendritic cells? |
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How do Dendritic cells sample their environment? |
pinocytosis endocytosis phagocytosis |
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If a dendritic cell encountered an antigen what would it do? |
Leave the tissue
through afferent lymphatics To T cell area of lymph nodes |
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What receptors found on a DC surface enable it to detect tissue damage or pathogen presence? |
TLR (toll like receptors) |
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What does an activated TLR lead to in a dendritic cell?
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1. increased expression of MHC 2 2. increased antigen presentation and processing ability 3. expression of CCR7 4. expression of costimulatory molecules |
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What is CCR7 and what does it do? |
Chemokine receptor Allows dendritic cells to make way to lymph nodes after antigen detection |
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Which costimulatory molecules are expressed when dendritic cells detect PAMPs or DAMPs? |
CD40 CD80 CD86 |
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What is the definition of tolerance? |
"a state of antigen specific unresponsivness to an antigen which under other circumstances can stimulate an active immune response" |
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Why is tolerance necessary |
prevent immune response to self or harmless antigens from food proteins, commensals and foetuses |
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Which diseases can be caused by a lack of tolerance? |
Type 1 diabetes Rheumatoid arthritis Crohns disease Coeliac disease |
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In Crohn's disease, what is the immune response responding to? |
harmless commensal bacteria |
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In coeliac's disease, what is the immune response responding to |
gluten - a wheat protein
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Why does the body create T and B cells capable of reacting with self (autoimmunity) or harmless foreign antigens? |
receptors produced through random genetic processes needed to create the many thousands of possible receptors we may need |
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What is the difference between central and peripheral tolerance? |
Central = tolerance to self antigens in primary lymphoid organs affects development of immature T and B cells Peripheral = tolerance to harmless foreign antigens, or tissue specific self antigens in secondary lymphoid organs affects mature T and B cells |
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What are the 4 mechanisms for tolerance?
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ignorance clonal deletion clonal anergy active regeneration |
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What is ignorance, in terms of tolerance? |
occurs when lymphocytes are normally not exposed to tissue antigens - can't make immune response - i.e. lens of eye or testis |
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What is clonal deletion? |
maturing lymphocytes encounter self antigen during development either in thymus (t) or bone marrow (b cells) leads to death of reactive cell |
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What is clonal anergy |
when a mature T cell encounters a self or foreign antigen in periphery which is presented on an APC without costimulatory molecules. Anergic T cells remain present but unresponsive for the antigen |
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What is active regulation? |
1st encounter with antigen results in T cell differentiation into a T regulatory cell. Generated by self antigens in Thymus or foreign antigens in periphery. |
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Comment on the level of B cell production through life |
generated through life production decreases with age |
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Development of B cells occurs... a) before birth b) after birth |
foetal liver
bone marrow |
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What is BcR and what does it recognise |
B cell receptor recognises antigens |
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What type of antigen can a BcR recognise? |
protein carbohydrate lipid DNA |
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What is the antigen binding component of the BcR made of? |
membrane bound antibody (mIg) Ig alpha Ig beta |
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What does clonal selection prevent?
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autoimmunity
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What is antigen independent B cell development? |
Ig gene rearrangment
generates functional BcR |
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Where does B cell development take place? |
Bone Marrow |
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What is antigen dependent B cell development, and where does it take place
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Bone marrow + periphery
BcR recognition of antigen drives it |
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What happens to Immature B cells expressing a BcR recognising self antigen. Thus B cell repetoire is,.. |
they are eliminated SELF TOLERANT |
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What happens in clonal deletion |
apoptosis driven by multivalent or membrane-bound antigens |
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Clonal anergy is driven by... |
soluble antigens B cells remain but BcR down regulated B cells become unresponsive |
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How does necrosis cause inflammation? |
Necrosis leads to -chromatin clumping -swollen organelles -flocculent mitochondria WHICH LEADS TO -disintegration -release of intracellular contents -triggers inflammation |
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What is SLE |
systemic lupus erythematosus autoimmune disease pathogenic anti-nuclear antigen autoantibodies associated with defects in apoptosis, clearance of apoptotic cells and B cell tolerance |
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What happens to immature B cells which don't undergo clonal deletion/anergy? |
Fully differentiate in spleen within a few days become mature B cells recirculate through lymph nodes |
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Why is T cell tolerance enough to ensure tolerance of B cells |
T cells activate most B cells. |
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Which type of T cell activates B cells?
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Th2 |
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what does B cell activation lead to? |
proliferation differentiation into memory or plasma cells |
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What kind of B cell produced antibodies
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B plasma cells |
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Which kind of B cells produce immunological memory
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B memory cells |
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How are B cells activated? |
1. Foreign antigen detected 2. Cross linked with BcR 3. Induces internalisation of antigen 4. Antigen processed internally 5. Peptide produced on B cell surface 6. Presented to Th cell |
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What do activated B cells form in medullary cords? |
Foci |
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What occurs in foci? |
differentiation of B cells |
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What is the first type of antibody to be produced by B cells? |
IgM |
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What is the location of class switching antibodies of B cells? |
B cell follicles - germinal centres |
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What occurs in germinal centres?
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- rapid B cell proliferation - somatic mutation - class switching IgM to IgG - differentiation |
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How common is a naive B cell for 1 particular type of antigen? |
rare/ low frequency |
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B cells entering the follicle have a half life of how long? |
3 - 8 weeks for naive cells that don't encounter antigens Memory cells can persist for years |
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Compare the affinities of initial IgM produced by B cells and the isotype post class switching. |
IgM = low affinity but rapid IgX (post class switch) = high affinity |
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What is the benefit of adaptive memory B cell response? |
response will be faster stronger |
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What is the typical lag phase of primary and secondary responses? |
1 = 4-7 days
2 = 1-3 days |
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What is the typical peak phase of primary and secondary responses? |
1 = 7-10 days 2 = 3-5 days |
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What is the main antibody secreted in the primary and secondary responses? |
1 = IgM 2 = IgG |
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Does the level of IgM get bigger or smaller in the secondary response compared to the primary?
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Smaller |
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The initial response is dominated by which part of the immune system? |
innate |
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What is Coryza |
inflammation of nasal linings produce nasal discharge |
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What is on the outside of influenza which aids it's virulence? |
Haemagglutinin Neuraminidase |
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How does hemaglutinin aid influenza's virulence? |
binds to sialic acid receptor on cell triggers endocytosis virus enter's cell |
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How does neuraminidase aid influenza's virulence? |
aids exocytosis |
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What are the host defences for influenza? |
mucus + cilia interferons innate antimicrobial proteins such as defences antibodies cytotoxic T cells |
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Where are antibodies present? |
serum and other body fluids |
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What is anti-serum |
serum which contains antibodies against more than one antigen |
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What is an antigen |
any molecule that can be bound by an antibody |
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Can antigens be from the host? |
Yes, (although we usually think of antigens as foreign matter, they can be from self) |
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What are the biological effects of antibodies? |
-opsonisation - aids phagocytosis via Fc receptors -neutralise bacterial toxins -immobilisation - flagella of motile bacteria -cytolysis - complement fixation |
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What are the stages of clonal selection?
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1. Each B cell has a different BcR 2. Antigen binds to the cognate BcR 3. Activation results in cell division and differentiation 4. Plasma cells secrete Ab of the same specificity |
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How many light chains does an antibody have? |
2 |
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How many heavy chains does an antibody have?
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2 |
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What grew letters can be assigned to the different types of light chains? |
kappa or lambda |
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What are the two regions of an antibody? |
Fab and Fc regions |
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What bonds hold the two sides of the antibody together? |
disulfide bonds |
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Which region of antibody is the antigen binding site |
tips of the Fab region |
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What are the domains of the antibody? |
VL, VH, CL, CH1, CH2, CH3
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What are 4 shapes of antigen binding sites? |
Groove Shallow surface Protrusion |
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Give an example of what binds to a pocket binding site on an antibody
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Haptens, such as ferrocene |
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Give an example of what binds to a groove binding site on an antibody |
HIV peptide |
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Give an example of what binds to a shallow surface binding site on an antibody |
HEL |
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Give an example of what binds to a protrusion binding site on an antibody |
HIV gp120 |
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What domains of an antibody don't change during class switching? |
VL CL VH |
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Where are the CH3 and CH2 domains of an antibody?
|
Fc region |
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What molecules are bound to antibody's and don't change during class switching? (not antigens)
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carbohydrates |
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What two domains are involved in the antigen binding site? |
VL and VH |
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In IgM, what is the greek letter assigned to it's heavy chain? |
Mu |
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What type of cells express IgM |
naive B cells |
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What type of shaped molecule is IgM |
pentameric |
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Which immune response is IgM most associated with? |
primary |
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What is the name of the chain that holds the individual antibody subunits together in IgM? |
J chain |
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IgM average serum level |
1.5 mg per ml |
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Half life of IgM in serum (days) |
10 |
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What is the molecular weight of IgM |
970 kDa |
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What are the functions of IgM |
Toxin and viral neutralisation by Ag binding Agglutination Fc complement activation Fc phagocytosis/opsonisation |
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Does IgM cross the placenta? |
NO |
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Which antibody is mainly membrane bound? |
IgD |
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What is notable about IgD's hinge region? |
it's longer than usual |
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What level of IgD is in the serum? |
trace |
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What are the functions of IgD |
co-receptor for B cells secreted in upper resp tract for defence against rest pathogens binds to basophils |
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When IgD binds to basophils, what does it induce the secretion of?
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anti-microbial factors such as LL37 + beta-defensin 3 pro-inflammatory cytokines such as TNF alpha + IL-1beta chemotaxtic factors such as IL8 and XCL10 Ab-inducing factors such as IL4 + BAFF |
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What greek letter is assigned to the heavy chain of IgD
|
delta |
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What is the molecular weight of IgD
|
184 kDa |
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What is the half life of IgD in serum? |
3 days |
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How many types of IgG are there in humans? Name them |
4 IgG1 IgG2 IgG3 IgG4 |
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In mice, there are also 4 types of IgG. Name them. |
IgG1 IgG2a, IgG2b, IgG3 |
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What are the functions of IgG |
toxin + virus neutralisation
-agglutination - Fc complement activation - Fc phagocytosis / opsonisation |
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do IgG cross the placenta via FcRn? |
Yes |
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Which list IgG's in order of their ability to activate the classical complement pathway |
3, 1, 2, 4 |
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Which IgG activates the alternative pathway |
none |
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List IgG's in order of their ability to be transferred across the placenta
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1, 3, 2, 4 |
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Which IgG's can bind to macrophage Fc receptors to aid phagocytosis? |
1, 3 (4 kind of but not well) |
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Which IgG can bind to mast cells and basophils |
none |
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What shaped molecules does IgA exist in? |
monomers, dimers and tetramers |
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In serum, what shape does IgA usually take? |
monomers |
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In external secretions, what shape is IgA usually? |
dimers or tetramers |
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What is the function of IgA
|
protection at external surfaces agglutination |
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How do infants get IgA? |
from their mothers through breast feeding |
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What is the name of the heavy chain of IgA |
either alpha1 or alpha2 |
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What is the molecular weight of IgA |
160 |
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Which form of IgA has a slightly higher presence in serum? |
1 3 mg per ml whereas 2 is 0.5 mg per ml |
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what is the half life of IgA in days in the serum |
6 |
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Which antibody has the lowest level in serum? |
IgE 5 x 10^-5 |
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When is serum levels of IgE increased
|
atopies |
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What additional domain does IgE have |
C-epsillon-4
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What is the molecular weight of IgE |
188 kDa |
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What is the half life of IgE in days? |
2 |
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What is the function of IgE |
interacts with FcepsillonR on mast cells expulsion of parasites at mucosal surface via inflammatory response using eosinophils |
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What unintended affect does IgE have against non harmful foreign matter? |
allergic response |
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What are the isotypes of all of the H chains of antibodies |
mu, delta, gamma 1,2,3,4 epsillon and alpha 1 and 2 |
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What are the isotopes of all of the L chains for all antibodies |
kappa, lambda 1,2,3 or 4 |
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What is the complexity of the BcR repertoire? |
2 x 10 ^27 |
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What is the name of the syndrome for people born without thymuses? |
Di George syndrome |
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What are the groups of effector T cells? |
Helper cells (Th cells) Cytotoxic T cells Regulatory T cells Memory T cells NK T cells |
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What do Helper T cells do? |
produce cytokines assist B lymphocytes to produce antibodies activate macrophages |
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What do cytotoxic T cells do? |
kill tumour cells kill infected tissue cells |
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What do regulatory T cells do? |
inhibit activity of other lymphocytes prevent autoimmunity |
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What do memory T cells do? |
generate secondary immune response |
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What do NK T cells do? |
act early in immune responses link innate and adaptive immunity |
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What do 90% of T cells express |
alpha beta T c R |
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What are the two subsets of alpha beta T cells? |
CD4+ CD8+ |
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What percentage of alpha beta T cells are CD4+
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60 - 70 % |
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What percentage of alpha beta T cells are CD8+ |
30-40 % |
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Which subset of T cells recognise MHCII |
CD8+
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What type of antigens are detected by CD8+ cells? |
antigens synthesised in cytoplasm or nucleus of infected cell |
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What IL is required to prime CD8 cells |
IL2 |
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Is costimulation required for CD8 cells to kill target? |
no |
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What enzymes are released by CD8 cells to kill target cells? |
perforin and granzymes from granules in T cell |
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What does perforin do? |
forms pores in cell membrane and intracellular vesicles |
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What do granzymes do? |
induce death by apoptosis |
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Do cytotoxic T cells lead to inflammation when they kill a target cell?
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no |
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How many CD8+ cells are needed to kill a target cell? a) 1 b) 5 c) many |
many |
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What process enables CD8+ cells to kill more than one target?
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recycling |
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What cytokine do CD8+ cells produce? |
gamma-interferon |
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What autoimmune disease can CD8+ cells cause? |
type 1 diabetes |
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Is costimulation required for CD4 helper cells? |
YES |
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What infects and kills CD4+ cells? |
HIV |
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How does HIV kill CD4+ cells? |
binds to CD4 molecule |
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What are the subsets of CD4+ cells? |
Th1 Th2 Th17 TFH |
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What differentiates the 4 subsets of CD4+ |
cytokines produced |
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What cytokines do Th1 cells produce |
gamma IFN TNF beta |
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What cytokines do Th2 cells produce |
IL 4,5,6,9,10,13 |
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What cytokine does Th17 produce |
IL17 |
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What is another name for TFH cells |
Follicular helper T cells |
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What do TFH cells produce?
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IL21 |
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What determines how a naive CD4+ cell differentiates? |
the way in which the foreign antigen is presented the nature of the inflammation which is present |
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What is the relationship between the subsets? |
Each subset is regulatory of the others |
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What causes a naive CD4+ cell to differentiate into a Th1 cell? |
IL12 produced by dendritic cells |
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What causes a naive CD4+ cell to differentiate into a Th2 cell? |
IL4
Transcription Factor: GATA-3 |
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What causes a naive CD4+ cell to differentiate into a Th17 |
TGF beta IL6 IL23 |
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What inhibits differentiation of a CD4+ cell into Th17 cell? |
gamma IFN |
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What causes a naive CD4+ cell to differentiate into a Tfh cell? |
IL6 IL21 |
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What role does gamma IFN play in CD4+ cell differentiation? |
Enhances IL12 production > IL12 promotes differentiation into Th1 cells. Inhibits Th17 production |
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What enhances the production of IL12 by dendritic cells? |
- gamma IFN
- interaction CD40 ligand (t cell) + CD40 (APC) |
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How is the production of gamma IFN by Th1 cells regulated?
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Transcription factor T-bet |
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What is the purpose if Th1 cells producing gamma IFN |
activated macrophages to kill intracellular infections and to release pro inflammatory mediators |
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What pro-inflammatory mediators does gamma-IFN promote macrophages to produce? |
TNF alpha IL1 IL6 |
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What can inappropriate activation of Th1 cells lead to?
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arthritis inflammatory bowel disease |
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What is needed from Th2 cells for B cell proliferation and differentiation during antibody production? |
IL4, 5, 6, and 13 |
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What affect does IL4 have on B lymphocytes? |
class switcher produce IgE and IgG1 |
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Inappropriate activation of Th2 cells leads to what diseases..? |
asthma hay fever (IgE mediated diseases) |
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What type of pathogens do Th2 cells protect against? |
extracellular pathogens - parasites etc |
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What is the purpose of Th17 cells producing IL17
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recruit and activate neutrophils |
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What is the purpose of Th17 cells producing IL22
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induces anti-microbial peptides induces tight junctions in intestine |
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What type of pathogens do Th17 cells protect against? |
extracellular bacteria and fungi |
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What does inappropriate activation of Th17 lead to? |
marked tissue inflammation |
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What do Tfh cells do after activation by antigen? |
migrate to B cell follicles of lymphoid organs |
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What type of TcR interaction is required by Tfh cells?
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high affinity TcR interaction
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What transcriptional repressor is required to Tfh production?
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Bcl-6 |
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What kind of B cells do Tfh cells interact with? |
B cells that are specific for the same antigen |
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What is the purpose of Tfh cells in the B cell follicles? |
drive the formation of the germinal centre |
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What is somatic hypermutation? |
intense proliferation of B cells and rapid mutation of antigen combining regions of the genes coding for their antibody molecules. - B CELL SELECTION FOR THOSE WITH HIGH ANTIGEN AFFINITY |
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What two molecules on the Tfh cell have to interact with their counter receptors on a B cell? |
ICOS CD40 ligand |
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What additional purpose do Germinal centres have in terms of providing a secondary immune response? |
generate memory T and B cells. |
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Are regulatory T cells mainly CD4 or CD8+ |
CD4+ |
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What are the two main groups of regulatory T cells? |
Natural Treg Inducible Treg |
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What costimulatory molecules are present on natural Treg cells? |
CD4+ CD25+ |
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What specific transcription factor must Natural Treg cells develop under, in the thymus? |
FoxP3 |
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What is the purpose of Natural Treg cells
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recognise self antigens prevent autoimmunity by producing TGFbeta and inhibiting APC |
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How does a Natural Treg cell inhibit APC
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CTLA4 on Treg surface removes CD80/CD86 from APC |
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What kind of antigens do inducible Treg cells recognise? |
self or foreign antigens |
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Where do inducible Treg cells differentiate from naive CD4+ T cells? |
after recgnition of an antigen in peripheral immune system |
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inducible Treg cells have many subsets - True or False |
True
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What do inducible Treg cells produce |
- some subsets produce IL10 selectively (Tr1) Others produce TGFbeta and function as regular Natural Treg cells |
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What molecule do NK T lymphocytes express? |
NK1.1 - natural killer molecule |
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What do NK T cells recognise? |
lipids on pathogens |
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Do NK T cells bind to MHC class I or II
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Both - not MHC restricted |
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What cytokines are produced in early immune responsed by NK T cells |
IL 4
gamma IFN ? |
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Where are gamma delta T cells rare and where are they more common?
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rare in blood + lymph nodes more common in skin, gut + other surfaces |
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Do gamma-delta T cells produce CD4 or CD8? |
Neither |
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What MHC class doe gamma-delta T cells interact with? |
not MHC restricted |
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What kind of antigens are recognised by gamma-delta T cells? |
conserved, non-peptide antigens (i.e. components of cell walls) |
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What is the function of the mediators released by gamma-delta T cells/ |
promote tissue repair |
