T Cell Activation

Question 1

Two types of TCR

Answer 1

• ~95% of T cells are traditional = alpha-beta

- non-traditional = gamma-delta

Question 2

very diverse type of TCR

Answer 2

traditional

- like a BCR, but recognizes MHC+peptide and does not hypermutate to change affinity

Question 3

place of education for traditional TCRs

Answer 3

thymus

Question 4

where are alpha-beta TCRs found?

Answer 4

blood and lymph nodes

Question 5

info about gamma-delta TCRs

Answer 5

• little diversity

- found in the intestine, uterus, and tongue

Question 6

Natural Killer T cells

Answer 6

• about 1% of human T cells
• has alpha-beta TCR and matures in thymus
• BUT TCR is limited and recognizes the non-classical MHC, CD1 = lipid antigens - tuberculosis immunity?

Question 7

CD3

Answer 7

• crucial signalling part of TCR

- delta, epsilon (two to one side with d and g), gamma, zeta (two to one side, the other side)

Question 8

This is versatile depending on the signal it receives, TCR can trigger

Answer 8

alpha-beta + CD3

• activation
• anergy
• apoptosis

Question 9

Second receptors to activate T cell

Answer 9

CD4/CD8 co-receptors for signalling

- help focus T cells on the proper MHC molecule, and stabilize the interaction

Question 10

How do T-cell co-receptors come about?

Answer 10

they (CD4/CD8) are “chosen” during the maturation in the thymus

Question 11

Co-stimulatory molecules on APCs

Answer 11

provide “amplification’ of the signal a T cell obtains from the TCR/MHC+peptide interaction

Question 12

Most common example of co-stimulatory molecule is …

Answer 12

B7 on the APC and its cognate receptor of CD28 on the T cell

- once T cell is stimulated this way, it is ‘rewired’ so the T cells needs less co-stimulation in the future

Question 13

Th cells helping CTLs

Answer 13

• activated Th cells at battle site can stimulate CTL proliferation through IL-2
• T help is necessary for CTLs to live longer, and for development of memory CTLs