ELISPOT: - peptide or protein (Oct/23/2007 )

By typical Elispot protocol, T cells were stimulated by peptide. I don't know how to get the peptide, can I just use protein to run elispot?

what i know is that Eli-spot can be used with PBMC..(WBC)..extracted from blood...
and i use PHA (phytohaemagglutinin ) 10 ug/ml with the cells to give a positive result..