I have been looking at all kinds of articles but it is not very clear for me. CD4+ and CD8+ T cells have different functions. However, they do both secrete IFNy. So is the function of IFNy secreted by both T cells the same?
Can IFNy secreted by CD8+ T cells only induce apoptosis? And if so, how?
Can someone tell me in detail how IFNy from CD8+ T cells exert actions?
IFNy is one of the primary effector cytokine involved in cell mediated immunity.
Lymphocytes (Both CD4 and CD8+) as well as certain myeloid cells are going to produce this cytokine following activation.
The receptor for this cytokine is expressed on both innate and adaptive immune cells.
IFNy produced by lymphocytes has multiple functions. Examples include:
-Upregulation of MHC-I on cells
-Promotion of maturation of macrophages and DCs
-May also act as chemoattractant for cells having the IFNyR
Interesting articles :
Article Interferon- derived from cytotoxic lymphocytes directly enha...
Seder, R., Ahmed, R. Similarities and differences in CD4+ and CD8+ effector and memory T cell generation. Nat Immunol 4, 835–842 (2003). https://doi.org/10.1038/ni969
To answer your Apoptosis question: CD8 T cells produce another effector cytokine called TNFa better known to induce apoptosis.
Maybe the CD8 IFNy induced Apoptosis which you mention is that which promotes AICD (for purposes of T cell homeostasis) . In which case IFNy only acts to promote caspases.
Check: Article InterferonIs Required for Activation-induced Death of T Lymphocytes
Just as a note for CD8 + T cells , other CTL responses include secretion of perforin , Granzyme B & Fas Ligand
Hope it helps
IFNg itself is the same protein regardless of the producing cells, but its effects are context-dependent.
IFNg from DC will stimulate CD8 T, for example.
IFNg from CD8 T will prepare fibroblast for apoptosis in case viral infection, etc.
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