The secondary cytotoxic response to allogeneic cells: the specificity of secondary cytotoxic effectors differs from that of primary effectors.

Following priming with alloantigen in vivo, a secondary cytotoxic activity of AKR mice (H-2k) was generated by in vitro stimulation with the same alloantigen. Such secondary effectors could lyse not only targets of a sensitizing haplotype but also third-party targets unrelated to sensitizing or responding cells. Such cross-reactive cytotoxicity of AKR secondary effectors were demonstrated not only by stimulation with C57BL/6 (H-2b) cells but also with C3H/He (H-2k) cells. It was observed that such cross-reactive secondary cytotoxicity was mediated by T lymphocytes, and required protein synthesis in secondary culture. These results suggested the possibility that the antigen receptors on such secondary cytotoxic effector cells have different recognitive specificity from that on primary cytotoxic effector cells.