Isolation of a human allo-peptide presented by HLA-B51 molecules

Recent studies have demonstrated directly that alloreactive mouse CTL recognize peptides presented by MHC class I molecules. However, there is no direct evidence that human alloreactive CTL recognize peptides presented by HLA class I molecules. We have isolated an HLA-B51 alloreactive CTL clone, 283, that did not kill the TAP defective cell lines T2 and.174, whereas it killed the TAP-positive cell line T1 and.174 cells transfected with TAP genes. These findings suggested that this clone recognizes a TAP-dependent allo-peptide. We attempted to isolate the human allo-peptide recognized by the 283 clone from HLA-B51 molecules. A naturally occurring HLA-B(*)5101 binding peptide isolated from T1 cells was recognized by the 283 clone. The peptide was also isolated from HLA-B(*)5101 molecules purified from C1R-B(*)5101 cells. In the present study, we directly demonstrated that a human alloreactive CTL clone recognizes peptide presented by HLA class I molecules.