Mutations in H-2Kb influence the specificity of alloreactive effector cells included in the repertoire of H-2Db-restricted cytotoxic T lymphocytes against Moloney leukemia virus

Dk-restricted antiinfluenza cytotoxic T-cell clone loses one of its two alloreactivities

K6, an influenza-specific cytotoxic T (Tc)-cell clone derived from C3H/He mice, was Dk-restricted. Further analysis showed that K6 also recognized Dd and Dq as allotargets. The clonal nature of the three recognition specificities was confirmed by cold-target cell inhibition. After extensive in vitro selection, K6 lost the ability to lyse Dd cells while retaining both other specificities. The role of the Lyt-2 molecule in antigen-specific self-H-2-restricted vs allospecific recognition was investigated by inhibition with the Lyt-2-specific monoclonal antibody 53-6.7. Both activities were proportionately inhibited, indicating that the Lyt-2 molecule is equally important for both recognition specificities of this Tc-cell clone.

Immunity against Moloney sarcoma virus in H-2Db mutant bm14 mice. Unimpaired tumor immunity despite absence of a virus-specific cytotoxic T-cell response

It was shown previously that B6.C-H-2bm14 (bm14) mice, carrying a mutation in the H-2Db locus, are unable to generate cytotoxic T cells (CTL) against Moloney murine sarcoma virus (M-MSV). We now report an analysis of tumor induction and regression kinetics and of immunity to the virus, following the injection of graded doses of M-MSV into C57BL/6 (B6) and bm14 mice. Contrary to expectation, bm14 mice showed slightly less tumors than wildtype B6 mice. Moreover, all bm14 mice that developed a tumor were able to reject this tumor, even after injection of the highest virus dose tested. From the spleen cells of bm14 mice that had rejected tumors, no secondary in vitro CTL responses could be generated, in contrast to strong CTL responses generated from B6 spleen cells. Although bm14 mice were unable to generate virus-specific CTL, they showed normal antibody and T-cell proliferative responses against Moloney virus, suggesting an intact T-helper-cell function. It is concluded that in bm14 mice, under the conditions tested, virus-specific CTL are not generated despite excellent tumor immunity. Therefore, this CTL response is not necessary for protection against M-MSV-induced tumors. Protection is likely to be mediated by a normal T-cell proliferative response.