So I know T cells do not recognize a full antigen, but require a peptide presented on MHC. I know some intracellular bacteria shed proteins that a somatic cell may process and present on MHC I for a CD8 T cell to recognize.
My question is: how - or whether - extracellular gut bacteria can initiate a T cell response? That is, they naturally only have the full antigen on their capsule/wall, they do not present a peptide-MHC complex... So how can these T cells recognize these gut bacteria? (and possibly destruct them...)
Any input would be highly valued!
P.s. I know there are alternative mechanisms involving antibodies, macrophages, NKs, etc... to combat bacteria, but I am specifically interested in finding out whether and if so how the CD8 T cell response is regulated
