gamma delta T cells II Flashcards
Do yD T cells require MHC and peptide presentation for activation?
No, but no other general antigen presenting molecule has been identified.
This means they can’t promote B cell antibody responses.
What are the similarites in the TCRs of aB and yD T cells?
Both have Ig domains in the V and C regions of TCR.
Both made up of structural (framework) and hypervariable regions.
They have CDR1,2 and 3.
What might the hypervariable region 4 be important in in yD T cells?
Not as variable, but might help to select for tissue specific ligands that determine yD T cell localisation.
Differences in CDR1 and 2 in yD T cells vs aB T cells.
CDR1 and CDR2 regions are longer in yD T cells, may prevent MHC binding via steric hinderance. Specific Vy and Vdelta CDR1/2 lengths may determine pairing of Vy and Vdelta chains.
Difference in CDR3 in yD vs aB T cells.
In TCR delta, the CDR3 region is longer and more diverse (8-21 vs 6-12 of a or B CDR3).
More like Ig heavy chain CDR3.
How do Vy9 Vdelta2 cells detect phosphoantigens like HMBPP?
Normally, butraphilin exists as a dimer- of BTN3A1 with BTN3A2/3. Upon phosphoantigen production (by tumour cells) or from MEP pathway of bacteria in infected cells, this changes the conformation of BTN3A1/2/3, which are able to activate Vy9Vdelta 2.
What other ligands apart from phosphantigens can yD T cells recognise?
Can recognise the MHC I like molecules MICA and MICB which are upregulated in stressed cells and by tumours.
May also recognise heat shock proteins
What MHC 1 like molecules do mice recognise (since these ligands not translated to mice)
Recognise MHC like molecules T10 and T22, which don’t present peptide.
What can regulate where yD T10/T22 cells go?
IfT10/T22 absent from thymus, then will go to the LNs. If present will go to the gut.
What subsets of yD T cells recognise MICA/B
Vy1Vdelta 1 and intraepithelial lympoctyes.
What functions do yD T cells have?
They are eraly and large producers of IFN-y and IL-17. They also highly express cytotoxic granzymes and perforins, as well as FasL and TNFa.
What markers can define whether they produce more IL-17 or IFN-y?
CD27+ IFN-y, CD27- IL-17
What chemokines suggest that they attract lymphocytes but not neutrophils?
EXpress CCL3,4, and 5 and lymphotactin to attract monocytes and lymphocytes.
What chemokines, not expressed by yD T cells attracts neutrohpils?
CXCR1-7.
What chemokines attract macrophages?
MCP1-144.
