how so T-cells recognise peptides in ICS assays? - (Jan/30/2013 )

Hello,


Let's say I'm using intracellular staining of IFN-gamma to identify CD8+ T-cells which have been stimulated by a peptide...
I'm just curious about how this works, that is, using synthetic peptides to stimulate the T-cells, because I thought T-cells
could only recognise peptide in the context of MHC.

Please explain how incubating these cells with free-floating peptides (if that is how its done at all...) results in the activation of
effector T-cells. Peptides on MHC-I, tethered at both ends are meant to loop upwards, providing a recognizable shape in the
CONTEXT of MHC... what am I missing here? I would be very grateful if someone could explain this, or even point me to an
appropriate article.


(p.s.: I do understand how the cytokines produced are trapped inside the cell, and how staining proceeds.)


Thanks.

Am I right to think that macrophages and dendritic cells from the spleen itself simply take up the peptides and
channel them to MHC-I on the surface through cross-presentation?

I'd be very grateful for some information on the molecular biology behind the ICS assay, when I'm testing individual peptides.

Thanks.