I searched the forums and basically I have the same question someone else had in this thread: http://www.protocol-...s-in-ics-assays . So maybe somebody can help?
I was wondering why in some assays, T cells and their TCRs do not require MHC-bound antigen and are stimulated only by 'free' peptides. In my books, both CD4+ and CD8+ T cells require peptide/MHC complexes for epitope recognition, so in theory this shouldn't work without APCs or at least multimers.
For example, in Elispot assays peptide stimulation can be used as a positive control, like shown on this page: http://www.mabtech.c...001004&MenuId=7 . At first I thought that APCs might take up the peptide and present it to the T cells. But then I discovered that T cells are stimulated even when there are no APCs around (enriched CD8+ cells or T cell clone), as is the case in the above link.
Can someone explain? Thanks for your help!