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22 Cards in this Set

  • Front
  • Back
First step in adpative immune repsonse/ T Cell activation
A naïve T cells encounters it’s specific antigen and is stimulated to differentiate into an effector T cell
How are antigens from the infection site?
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
Where is immune repsonse intiated?
In secondary lymphoid tissue
Dendritic cells
Only known function is to trigger T cell responses
Migratory: carry antigen load from infection to secondary lymp tissue
Macrophages
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
Cells which present antigen to CD4+ T Cells
Dendritic Cells
Macrophages
B Cells
LFA-1 and ICAM-1
LFA-1 (integrin) on Lymphocyte will eventually bind with ICAM-1 tightly to allow lymphocyte to leave blood and enter lymph node
What are the two signals required for T cell activation by APC?
V region on the CD4+ interacts with peptide bound in cleft of MHC Class II
Interaction of B7 (CD 80/86) with CD28
Activation of Helper T Cells
Induces intracellular signalling; activation of Protein Kinase C and Tyrosine Kinase
Expresses IL-2R
What is expressed on Activated T Cells?
Beta and Gamma chains which have very low affinity
Add alpha chain and the affinity rises dramatically
What is the most important surface protein involved in CD4+ effector function?
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
TH1 Cells
Activates CD8+ CTL, NK, and Macs
Production of opsonizing antibodies
Impt. in viral infections
Makes IL-10 for inflammatory response
TH2 Cells
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
What is the role of IFN gamma and TH1?
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
What are the two main IL made by TH2 cells
IL-4 which causes a class switch to IgE which is important in regulating allergy
And IL-5 which activates Eosinophil which fights parasites
Only things repsonsible for B cell signaling
Tyrosine Kinase
Protein Kinase C
Changes in gene expression
Remember that B cells undergo parallel events!
The main event in T Cell and B Cell interaction
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
What intially primes the T Cell?
The Dendritic cell followed by the B cell later
What do cytokines do to B cells?
Made by T cells they stimulate the B cell to increase production of Ig and Class switch
What are some characteristic features of a primary repsonse?
IgM>IgG
Low antibody affinity
Induced by all Ig
High doses of antigen required for immunization
What are some characteristic features of a secondary immune response?
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
What do T independent antigens cause proliferation of?
IgM secretion