THE ROLE OF PEPTIDE IN THE POSITIVE SELECTION OF CD8(-CELLS IN THE THYMUS() T)

Recent experiments using fetal thymus organ culture (FTOC) systems der ived from class I deficient mice have provided evidence supporting the view that specific recognition of class I MHC plus peptide complexes is required for the positive selection of CD8(+)T cells. The addition of class I binding peptides to FTOC systems derived from beta 2-microg lobulin and TAP 1 deficient mice induced the positive selection of CD8 (+)T cells in a peptide specific manner The specific recognition of pe ptide during positive selection implies that the repertoire of specifi city's exhibited by CD8(+)T cells is at least in part determined by th e repertoire of self-peptides presented by class I MHC in the thymus.