NKC + GD T cells

Question 1

What are the functions of gamma-delta T cells?

Answer 1

Regulate function of stromal cells by secretion of g-fx
Prime AB T cells because have unique endocytic function amongst lymphoid cells - take up and present Ag
Mature DC
Cause lysis target cells - infected or stressed
Release cytokine and chemokines:
i. recruit new cells to the site of infection
ii. activate Th1/Th17 response
Capable giving B cell help, in particular IgE production

Question 2

What is significant about the functions of gamma delta T cells?

Answer 2

Plastic response with rapid activation
Very important as has wide panoply of functions
May link innate and adaptive response (because recruits DC + AB T cells)

Question 3

Give some genetic background to GD T cells

Answer 3

Gamma chain located in alpha locus
Has limited no V-gene segments in both γ and delta loci
Delta has larger no diversity segments

Limited pairing between gamma + delta chains
Junctional diversity allows many potential CDR3 seq
Insertion nucleotides in CDR3 seq widens diversity despite limited VDJ segments

Question 4

How much of the peripheral blood T cells do GD T cells make up?

Answer 4

1-10%

More in tissues

Question 5

How are the GD T cells localised to the tissue?

Answer 5

Theory - specific receptor localises cells to a specific tissue/compartment

eg. Vγ9Vδ2 T cells form majority pop peripheral blood
eg. Vδ-1 expressed epithelial tissue and resident in liver

Localisation due to BTnl - butyrophilin like molecules
Different tissues express different types of these molecules
eg. Humans - intraepithelial cells express Vγ4 binds Btnl 3/8
locates Vγ 4 cells to small intestine
cells recognise Btnl3 - molecules expressed most surfaces but the conformation molecule can be altered when activated
Enables recognition Vγ9Vδ2, these T cells can kill that cell and release cytolytic payload