Quiz 3 Flashcards
Which MHC class molecule is bound by CD4+ versus CD8+ presenting cells?
Class II is bound by CD4+
Class I bound by CD8+
Which genes are expressed in MHC class II molecules versus MHC class I?
DP, DQ, DR - class II A, B, C (has beta 2 microglobulin)- Class I
Which cells present class II MHC genes versus class I?
Profession antigen presenting cells - class II All nucleated cells - class I
What cytokine up-regulates type I MHC?
IFN-alpha, IFN-Beta
What are the two types of cells called when associated with class II versus class I to their respective T-cells>?
Class II - antigen presenting cell (CD4 helper)
Class I - target cell (CD8+ cytotoxic)
What is the endogenous pathway?
Takes antigens from cytosol, degraded in the proteosome and trasported via TAP to become class I
What is the exogenous pathway?
Takes antigens from the extracellular milieu, MHC II associate with invariant chain, CLIP, presented on plasma membrane
What is the process of T cell development?
Hematopoiesis -> pro T cell (thymus) -> double neg (pre T)–> double positive (immature T cell) –> Single positive stage (mature Th/Tc cell) –> Naive T cell enters circulation
What are the two signals that t cells need for activation?
TCR engagement (TCR:antigen+Self-MHC and a costimulatory signal (CD28:B7 APC) -those only getting one signal is anergized
What does IL-2R bind and do?
IL-2R is a trimeric receptor needed for IL-2 binding and signaling at cytokine levels (T cell proliferation)
alpha - low affinity
beta/gamma -0 intermediate affinity
alpha/beta/gamma - high affinity
What is the difference between effector and naive t cell rolling?
Naive T cell rolling/diadepsis by sialy-Lewis (l-selectin), effector T cells through E/P-selectin
How is the t cell immune response down regulated?
Stop synthesis of IL-2/IL-2R and increased expression of TGF-Beta
What does Th1 secrete?
Makes IL-2, IFN-gamma, - USEFUL FOR CELL MEDIATED IMMUNITY
Induced by IL-12, IFN-gamma
What is Th1 particularly effective against?
Viruses, intracellular bacteria, malignant cells, fungi, extracellular bacteria
What does Th2 make?
IL-4, IL-5 - USEFUL FOR HUMERAL IMMUNITY
Induced by IL-4, IL-10
What is Th2 effective against?
Extracellar bacteria, helmithic parasites, extracellular viruses, allergic disease
What do Treg cells make?
TGF-beta, IL-10 for downregulation of immune response
Induced by TGF-beta, and low IL-6, IL-23
What does Th1 promote versus Th2?
Th1 - activates macrophages, NK cell, and increased cytotoxic activity
Th2 - b cell activation and antibody production, and isotype switching
What is the difference between memory and naive CD4 t cells?
CD45RO - memory
CD45A - naive
what are other mechanisms of CD4 t cell activation?
Mitogens - non-specifically activate T cell or B cell Superantigens - trigger TCR but are NOT processed, capable of bind directly to MHC class II to activate a significant number of T cells
What is the role of Th17 cells?
They are proinflammatory cells, induce neutrophil recruitment, produce IL-17, IL-6, induced by IL-23, IL-6, TGF-Beta, and lack of other cytokines until Th1/Th2 are upregulated
Which antigens stimulate B cells directly in absence of T cell help?
LPS, and polysaccharides with repeating identical determinants
-Produces IgM»>Ig anything else
Which helper cell aids in B-cell proliferation and how does it do it?
BCR binds antigen, Th2 cells deliver 2nd signal via CD40L and cytokines
What co-stimulatory signals are required for B-cell activation?
CD28 on T cells & B7 Complex (CD80/CD86) on Bcells
CD40L on T cells and CD40 on B cells