If CD8 T cells have been activated in vivo, would in vitro stimulation with an agonistic anti-CD3 antibody alone (no agonistic anti-CD28 stimulation) cause degranulation (stainable CD107a protein) during a 4-6 hour co-incubation?
Hi Brett
In general terms, I would say yes, though there would be caveats. There are definitely CD8+ memory T cell populations (therefore previously activated) that have no CD28 on their surface, which respond by degranulation to peptide only stimulation (i.e. no CD28 co-stimulation) and these can be readily detected ex vivo from humans. However, if you're attempting to carry this out as an in vivo model, other factors may come into play, such as what you activate with in vivo and how quickly you isolate the CD8+ T cells and activate them in vitro.
Hope that helps
Ed