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22 Cards in this Set
- Front
- Back
First step in adpative immune repsonse/ T Cell activation
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A naïve T cells encounters it’s specific antigen and is stimulated to differentiate into an effector T cell
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How are antigens from the infection site?
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Via dendritic cells and macrophages to secondary lymphocyte tissue
Both can uptake, process, and present but dentric cells are better b/c of their ability to migrate |
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Where is immune repsonse intiated?
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In secondary lymphoid tissue
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Dendritic cells
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Only known function is to trigger T cell responses
Migratory: carry antigen load from infection to secondary lymp tissue |
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Macrophages
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Range of function:
Produce cytokines and chemokines Kill via O2 dependent mech. Effector cell for activated T Cells Enhanced by presence of INF Gamma Resident in tissues: Non migratory |
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Cells which present antigen to CD4+ T Cells
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Dendritic Cells
Macrophages B Cells |
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LFA-1 and ICAM-1
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LFA-1 (integrin) on Lymphocyte will eventually bind with ICAM-1 tightly to allow lymphocyte to leave blood and enter lymph node
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What are the two signals required for T cell activation by APC?
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V region on the CD4+ interacts with peptide bound in cleft of MHC Class II
Interaction of B7 (CD 80/86) with CD28 |
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Activation of Helper T Cells
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Induces intracellular signalling; activation of Protein Kinase C and Tyrosine Kinase
Expresses IL-2R |
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What is expressed on Activated T Cells?
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Beta and Gamma chains which have very low affinity
Add alpha chain and the affinity rises dramatically |
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What is the most important surface protein involved in CD4+ effector function?
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The activation marker CD40
Which is expressed on macrophages dendrtic cells and B cells Binding of it activates these cells and allows for killing of microbe |
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TH1 Cells
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Activates CD8+ CTL, NK, and Macs
Production of opsonizing antibodies Impt. in viral infections Makes IL-10 for inflammatory response |
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TH2 Cells
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Favor activation of B cells for antibody production
Class switching to IgE; for allergic rxn Important in parasitic infections and allergy Makes IL-10 for inflammatory response |
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What is the role of IFN gamma and TH1?
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TH1 makes IFN gamma whic can either activate macrophages or create a complement binding with B Cell and Opsonizing the antibodies via the Fc Receptor
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What are the two main IL made by TH2 cells
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IL-4 which causes a class switch to IgE which is important in regulating allergy
And IL-5 which activates Eosinophil which fights parasites |
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Only things repsonsible for B cell signaling
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Tyrosine Kinase
Protein Kinase C Changes in gene expression Remember that B cells undergo parallel events! |
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The main event in T Cell and B Cell interaction
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the interaction between CD40L (T Cell) and CD40 (B Cell)
T Cell needs antigen which B Cell provides so it stays activated and does TWO THINGS: Stay put Make cytokines or CD40L |
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What intially primes the T Cell?
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The Dendritic cell followed by the B cell later
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What do cytokines do to B cells?
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Made by T cells they stimulate the B cell to increase production of Ig and Class switch
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What are some characteristic features of a primary repsonse?
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IgM>IgG
Low antibody affinity Induced by all Ig High doses of antigen required for immunization |
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What are some characteristic features of a secondary immune response?
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Predominatly IgG or in certain situations IgE or IgA
High affinity for antibody Induced only by protein antigens Low dose of antigen required for immunization |
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What do T independent antigens cause proliferation of?
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IgM secretion
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