Test 2: T cell Maturation and Activation

Question 1

What is the difference between the receptors of innate and adaptive immunity?

Answer 1

receptors of adaptive immunity are clonal

Question 2

What do T cells recognize?

Answer 2

recognize peptides displayed by MHC molecules

Question 3

What is the structure of T cell receptor?

Answer 3

membrane-bound heterodimeric protein composed of an alpha chain and beta chain with a variable and constant region

Question 4

What is the binding site for MHC class I?

Answer 4

variable domains of alpha chains

Question 5

What is the binding site for MHC class II?

Answer 5

variable domains of alpha and beta chains

Question 6

In gremlin organization of T cell receptor gene location, what accounts for the diversity in gene segments?

Answer 6

somatic recombination

Question 7

What is the recombination of TCR gene segments?

Answer 7

random selection of segments

Question 8

What are the steps of mediation by lymphocyte specific VDJ recombinase that brings 2 segments close together?

Answer 8

• first step: recombination of D and J segments
• second step: recombination of V segments with fused D-J element
• third step: recombination of C segment fused V-D-J element

Question 9

Which diversity of TCR is unlimited: combinatorial vs junctional?

Answer 9

junctional diversity has tremendous diversity

Question 10

What does weak recognition of MHC+ peptide lead to?

Answer 10

selection of selected T cells that are single positive

Question 11

What happens to both strong recognition and no recognition of MHC+ peptide?

Answer 11

lead to death
- strong recognition= negative selection
- no recognition= neglection

Question 12

What happens with antigen recognition by T cells without costimulation?

Answer 12

induce unresponsiveness

Question 13

What must happen for T cells to proliferate?

Answer 13

engagement of B7 on AP by CD28 on T cells that provide signal 2 and induce proliferation

Question 14

What are inhibitory receptors for in activated T cells?

Answer 14

critical for limiting and terminating immune response

Question 15

How are CD8 T cells activated?

Answer 15

concomitant activation of CD4 T cells provide help to CD8 T cells via IL-2 production which allow for proliferation and differentiation

Question 16

How do T cells expand and contract?

Answer 16

antigen-specific T cell clones expand in response to antigen to provide a large pool of effector cell to fight infection

Question 17

How do effector CD4 T cells develop?

Answer 17

naive T cells proliferate/differentiate once acting with antigen

Question 18

What happens to the effector T cells that do not leave lymph nodes?

Answer 18

Tfh move in follicle to function as helping B cells

Question 19

What is the function of CD4 helper T cells?

Answer 19

• activate phagocytes via IFNy production and CD40-CD40L
• activate B cells to produce Ig via cytokine production and CD40-CD40L

Question 20

How do naive and effector T cells migrate?

Answer 20

combination of adhesion molecules and chemokine receptors allow for T cell movement

Question 21

What promotes cell survival in maturation of thymocytes?

Answer 21

expression of pre-TCR and TCR
- cells that do not express functional receptors die

Question 22

What is the difference between naive T cells and effector T cells in regards to their location?

Answer 22

naive T cells circulate from lymph node to lymph node in search of their antigens while effector T cells get migrated to antigen sites in tissues to get reactivated and carry their function