Cell Mediated Immunity

Question 1

Helper T cell activation

Answer 1

binding of TCR to MHC 2 peptide complex (antigen binding), costimulatory molecules (B7:CD28), cytokines (IL-1, IL-6, TNF alpha) from APC to T cell

Question 2

What determines T cell specialization

Answer 2

by antigen presented on MHC class 2

Question 3

TH 1 cells

Answer 3

intracellular pathogens, promotes cell mediated immunity

IFN gamma (inhibits TH2, activates macrophages), IL-2 (turns CD8 cytotoxic), TNF alpha

Question 4

TH 2 cells

Answer 4

promotes humoral immunity, extracellular pathogen removal

secretes IL-4, IL-5 (activates B cell, promotes class switching)

Question 5

antibody dependent cell mediated cytotoxicity (ADCC)

Answer 5

NK cells, macrophages and monocytes, neutrophils, eosinophils

Question 6

Cytotoxic cells (CTL) kill by

Answer 6

kill by perforins, cytokines (TNF), granzymes (serine proteases)

Fas ligand on CTL can interact with Fas on target cell to cause apoptosis of target cell

Question 7

interleukin 2 (IL-2)

Answer 7

cytokine produced by activated naive T cells to proliferate

proliferation of T cell

Question 8

interleukin 7 (IL-7)

Answer 8

secreted by APC to ensure T cells survive

Question 9

LFA-1:ICAM-1 interactions

Answer 9

how T cells initially binds to APC, not involved in the activation of T cell, induces conformational change in APC that prolongs cell to cell contact

Question 10

what happens when T cell meets non bacterial protein antigen

Answer 10

without bacteria, non bacterial protein will be taken up by macrophage but no B7 will be expressed (unstimulated macrophage). T cell will still bind to MHC presenting non bacterial protein but without co-stimulation, there will be no T cell proliferation/activation

Question 11

what happens when T cell meets bacteria and non-bacterial protein

Answer 11

results in proliferation/differentiation of T cells specific for nonbacterial protein

Question 12

What would violate the two signal model for T cell activation

Answer 12

If you have a strong enough signal (MHC binds tightly to TCR) you may not need CD28:B7 costimulation.

Question 13

How do you turn off T cell response

Answer 13

elimination of antigen, elimination of stimuli, IL-2/IL-2R signaling to proliferate, kill immunoregulatory cells

Question 14

TNF alpha (tumor necrosis factor)

Answer 14

activates endothelium to induce macrophase binding and exit from blood vessel at site of infection

Question 15

CD8 T cells effector molecules

Answer 15

perforin, granzymes, granulysin, fas ligand

Question 16

First Checkpoint (T cell development)

Answer 16

mediated by pre-TCR, beta selection, between double negative and double positive, determined by beta chain rearrangement

Question 17

Second Checkpoint (T cell development)

Answer 17

mediated by alpha Beta TCR, between double positive and single positive, positive/negative selection

Question 18

CTLA-4

Answer 18

master regulator of T cell activation, synthesized by T cell and binds to B7 with greater affinity removing co-stimulation.

Question 19

Factors in turning off T cell response

Answer 19

elimination of antigen, elimination of other stimuli, IL-2/IL-2R signaling via T regulatory cells, killing by immunoregulatory cells via Fas-Fas ligand

Question 20

surface cathepsin B

Answer 20

protects CTL from self destruction after degranulation

Question 21

proteinase inhibitor 9

Answer 21

serpin that inhibits granzyme B, expressed by CTL, dendritic cells, endothelial cells, some tumors

protects CTL from self destruction after degranulation