CMB1003/L25 Cell-mediated Specific Immunity II

Question 1

What are MHC molecules encoded by?

Answer 1

HLA
Human leucocyte antigens

Question 2

Describe the 3 genes and corresponding region of MHC class I.

Answer 2

HLA-A, HLA-B, HLA-C
A1-3
All pair with B2-microglobulin

Question 3

What are the sides and floor composed of in class I MHCs?

Answer 3

Sides - 2 a-helices
Floor - 8-stranded B-sheet

Question 4

What are both chains encoded by in MHC class II?

Answer 4

MHC (polymorphic)

Question 5

What are the 3 types of class II MHC molecules?

Answer 5

HLA-DP, HLA-DQ, HLA-DR

Question 6

What are the 2 sides and floor of MHC class II molecules composed of?

Answer 6

Sides - a-helices
Floor - 8-stranded B-sheet forms a groove

Question 7

Describe presentation by MHC class I molecules. (5)

Answer 7

Antigen synthesised in cytoplasm
Protein cleaved to peptides by proteosome
Peptides transported to endoplasmic reticulum by pore-forming TAP complex
Peptides bind to MHC class I molecules
MHC-peptide complex transported to cell surface

Question 8

What prevents binding in class II MHCs?

Answer 8

Invariant chain

Question 9

Describe presentation by MHC class II molecules. (7)

Answer 9

MHC class II molecules produced in ER associate with invariant chain
MHC class II moves from ER to vesicles - invariant chain broken down
Antigen engulfed bu APC
Protein cleaved to peptide fragments by acid activated proteases
Vesicles with peptides fuse with vesicles containing MHC II molecules
MHC II molecules binds peptide fragment
MHC-peptide complex transported to cell surface

Question 10

What is required for TCR signaling? (2)

Answer 10

CD3 activity
T cell receptor binding

Question 11

What does TCR binding lead to?

Answer 11

TH1/2/TFH/TH17 differentiation

Question 12

What occurs directly following CD4 stabilisation?

Answer 12

Lck causes phosphorylation cascade