T Cell Subset And Function

Question 1

The main cell type that causes activation of naive T cell is

Answer 1

Dendritic cell

Question 2

What type of blood vessel do T cells pass through before they enter the lymph nodes

Answer 2

High endothelial venules

Question 3

Which receptors on T cells promotes movement into lymph nodes

Answer 3

CCR7 and L selectin

Question 4

How do T cells leave the lymph nodes

Answer 4

Down regulation of CCR7 on T cells once they enter the lymph nodes allowing them to exit
S1PR1 on T cell binds to S1P molecule and follow S1P gradient causing it to leave the lymph nodes to travel towards the site on infection

Question 5

What causes bond between t cell and APC to prolong

Answer 5

LFA 1 on T cell binds to ICAM 1 on APC weakly initially
Complimentary fit of MHC with TCR causes conformational change on LFA1 causing it to bind stronger to ICAM 1 resulting in prolonged cell-cell contact

Question 6

Signals required for T cell activation and proliferation

Answer 6

Complimentary binding of MHC to TCR results in signal 1

Binding of B7 on APC to CD28 on T cell causes costimulatory signal which is signal 2

Question 7

Receptors that regulate action of T cells

Answer 7

CD28 on T cell binds to B7 of APC to produce stimulatory signal
CTLA 4 on T cell binds to B7 of APC to produce inhibitory signal
PD1 receptor on T cell binding leads to inhibitory signal

Question 8

Downstream signalling leading to t cell activation

Answer 8

CD4/8 is associated intracellularly with LCK
Upon activation and co-stimulatory signal, LCK phosphorylizes ITAM and ZAP70 which leads to further downstream signalling resulting in NFAT, NFKB, AP-1 activation which causes increased protein synthesis

Question 9

What is another name for IL2?

What is the 2 types of receptors for this cytokine and where is it found?

Answer 9

T cell growth factor
Moderate affinity IL2 receptor, Beta and gamma sub unit found in Naive T cell
High affinity IL2 receptor , Alpha, Beta and Gamma found in Effector T cell

Question 10

Other markers apart from IL2 for T cell proliferation

Answer 10

CD 69 and CD40

Question 11

Cd number of B7-1 and B7-2

Answer 11

CD80 and CD86

Question 12

Full proliferation and differentiation of naive CD8 T cell requires

Answer 12

Complimentary binding of CD8 TCR to MHC1 of APC
Co-stimulatory signal
T helper cell - produce IL2 and activate APC to produce CD40 to further stimulate T cell differentiation

Question 13

T cell subsets and the cytokines produced

Answer 13

Th1 = IFN gamma
Th2 = IL4, IL5, IL13
T17 = IL17, IL22

Question 14

Production of IL12 by APC causes what

Answer 14

Activation of NK cells to release IFN gamma

IL12 and IFN gamma causes T helper cell to become Th1

Question 15

What are the effects of Th1 cell

Answer 15

Produce IFN gamma
Interact with macrophages via CD40 to make them highly microbicidal
Mainly combats bacteria and parasite

Question 16

How T cell subset affects other T cell subsets

Answer 16

Th2 secretes TGF Beta and IL10 which inhibits activation and growth of Th1
Th1 secretes IFN gamma which inhibits Th2 proliferation

Question 17

What are the 2 category of memory T cells

Answer 17

Central memory T cell = remains in lymph node

Effector memory T cell = remains in peripheral tissue

Question 18

Cytotoxic contents used by CD8 T cells

Answer 18

1. Perforin = forms pore in target membrane
2. Granzyme = cause apoptosis
3. Granulysin = cause apoptosis

Question 19

Features of macrophages activated by CD4 t cells

Answer 19

1. Increased lysosomal enzymes
2. Increased ROS
3. Promotes Inflammation
4. Recruit more leukocyte

Question 20

What are the effects of Th2 cells

Answer 20

IL4 stimulate B cell to produce IgE
IL5 causes Eosinophil activation against Helminth
IL4,13 stimulate B cell to produce intestinal secretion and peristalisis
IL4, 13 also causes activation of macrophage to enhance tissue repair

Question 21

What are the 2 types of macrophages and their functions

Answer 21

M1 = activated by Th1, pro inflammatory, carries out phagocytosis of bacteria and parasite
M2 = activated by Th2, carries out wound repair

Question 22

Th17 cell function

Answer 22

Produce IL17 and IL22

IL17 causes inflammation, neutrophil response, antimicrobial peptide synthesis and increased barrier integrety

Question 23

What is the only type of inhibitory T cell subset

Answer 23

T regulatory cells

Question 24

What is the function of Tfh

Answer 24

Antibody production for all types of infection