Differences in antigen recognition and cytolytic activity of CD8+ and CD8- T cells that express the same antigen-specific receptor

CD8(+) and CD8(-) T cell lines expressing the same antigen-specific receptor [the 2C T cell receptor(TCR)] were compared for ability to bind soluble peptide-MHC and to lyse target cells, The 2C TCR on CD8- cells bound a syngeneic MHC(Kb+)-peptide complex 10-100 times less well than the same TCR on CD8(+) cells, and the CD8(-) 2C cells lysed target cells presenting this complex very poorly. surprisingly, however, the CD8(-) cells differed little from CD8(+) cells in ability to bind an allogeneic MHC (Ld+)-peptide complex and to lyse target cells presenting this complex. The CD8(+)/CD8(-) difference provided an opportunity to estimate how long TCR engagements with peptide-MHC have to persist to initiate the cytolytic T cell response.