T-Cells, Effector Functions and the MHC

Question 1

How are T-cell antigens recognised?

Answer 1

T-cell surface receptors recognise foreign molecules which are bound by another protein
proteins encoded by genes called the MHC complex genes, found in antigen presenting cells
MHC have peptide binding grooves

Question 2

Function of MHC?

Answer 2

MHC1 - associates with B2 microglobulin
MHC2 - ab heterodimer
Purpose is to display foreign peptides to the immune system

Question 3

Where are MHC1 and MHC2 found?

Answer 3

MHC1 - presents peptides derived from proteins synthesised within the cell
MHC2 - presents peptides on the outside

Question 4

How MHC 1 eliminate viral cells?

Answer 4

proteins by the virus are loaded on MHC1 molecules
they are put on the cell surface displaying those peptides
cells are then attracted to these peptides

Question 5

The two main classes of T-cells?

Answer 5

MHC1 molecules present a TCR called CD8 which are cytotoxic t-cells
MHC2 molecules coexpresses a receptor called CD4 which are helper t-cells

Question 6

Activation of T-cells?

Answer 6

Signal 1 is required for activation of a t-cell
if the t-cell and t-cell receptor and MHC molecules dont have a good fit then the t-cell doesn’t become activated
Signal 2 is stimulation by antigen presenting cells which bind to molecules like CD28 and CD86.
when t-cell gets both these signals they can divide and produce cytokines

Question 7

How do CD8 t-cells kill?

Answer 7

They seek out and destroy dangerous cells by binding to their target and using cell-cell interactions and secretion of cytolytic cytokines including perforins and granzymes

Question 8

Features of Th1?

Answer 8

secretes IFN-y and IL-2
allows CD8 t-cells to differentiate and express cytokines and granzymes
promotes differentiation of macrophages

Question 9

Features of Th2?

Answer 9

Produce IL-4 and IL-13 which promote division of B-cells, class switching and affinity maturation of the antibody
allows differentiation into plasma cells
promotes eosinophils

Question 10

Features of Th17?

Answer 10

Involved in bacteria and fungi and they secrete IL-17, IL-21 and IL-22
Promote secretion of antimicrobial peptides and aiding in wound healing
provides help for neutrophils

Question 11

Features of Treg?

Answer 11

prevent immunopathology
regulate t-cells
down regulate other response
supress stimulatory activity of APC
supress antibody production
supress function of immune cells