Allopeptides abrogate target cell lysis by anti–HLA-B7 CTLs.

(A) Anti–HLA-B7 CTLs lysed HLA-B7 target cells but not non–HLA-B7 control cells. (B) CTLs raised against stimulator cells efficiently lysed target cells, whereas CTLs raised against HLA-B7–derived synthetic peptides poorly lysed target cells.(C) P8, P10, and P11, but not P3 or P12, blocked cytolysis of target cells by anti–HLA-B7 CTL UWB7 in a concentration-dependent manner. (D) In contrast, P3 and P4—both HLA–A2-derived peptides—blocked target cell lysis by an anti–HLA-A2 CTL line, UWA2. P8, P10, and P11 (HLA–B7-derived peptides) did not modulate target cell lysis.