T Lymphocyte and Antigen Recognition

Question 1

What do all T cells express and what does it do?

Answer 1

CD3

associates with TCR

Question 2

What are the 2 T cell populations? How do they differ?

Answer 2

CD4 co receptor positive - peptide on MHC class II 
CD8 co receptor positive - peptide on MHC class I

Question 3

What do co receptors do?

Answer 3

bind to conserve part of MHC, increase avidity of T cell-target interaction and key for signalling

Question 4

Give function of CD8 T cells

Answer 4

Tc or cytotoxic
secret cytokines
apoptosis of target cell

Question 5

Give function of CD4 T cells

Answer 5

Th cells
secret cytokines
recruit effects of innate immunity
activate macrophages
increase B cell response

Question 6

What does T cell selection depend on?

Answer 6

which MHC molecule the TCR interacts with

Question 7

How many recombination events do the alpha and beta chain have?

Answer 7

alpha = 1 (V+J) 
beta = 2 (V+J+D)

Question 8

What are the 3 main subsets of T lymphocytes?

Answer 8

CD8+ CTL
CD4+ Th1
CD4+ Th2

Question 9

give the functions of MHC

Answer 9

display samples of internal cell contents at cell surface for possible immune cell recognition
markers of self
indicate cell health

Question 10

Which antigens are involved in organ transplant and which are involved in immune response?

Answer 10

MHC class I = transplant 
MHC class II = immunity

Question 11

define MHC

Answer 11

group of tightly linked genes importune in specific immune response

Question 12

What length of peptide do MHC class I/II present?

Answer 12

MHC class I = 8-10 A.A
MHC Class II = greater than 13 A.A

Question 13

How do peptides bind to MHC?

Answer 13

binding pockets of MHC bind to A.A side chains called anchor residues

Question 14

Give characteristics of MHC gene expression

Answer 14

polygenic

co-dominant

Question 15

On which cells are MHC class I/II present?

Answer 15

MHC class I = all nucleated cells
MHC class II = antigen presenting cells

Question 16

List the antigen presenting cells and where they are found

Answer 16

dendritic - widely spread e.g skin
B lymphocytes - lymphoid tissues
activated macrophages - lymphoid tissues

Question 17

What are endogenous antigens? Which T cell subset molecule do they interact with?

Answer 17

antigens that are synthesised inside the cell e.g. virus
class I restricted CD8 T cells

Question 18

What are exogenous antigens? Which T cell subset molecule do they interact with?

Answer 18

antigens that are captured from outside
class II restricted CD4 T cells