Target determinants for F1 hybrid anti-parental H-2d cell-mediated lympholysis: self antigens controlled by the D end.

The immunogenetic specificity and reactivity with syngeneic target cells were determined for (C57BL/6 x DBA/2)F1 anti-parental DBA/2 cytotoxic T lymphocytes (CTL) elicited in primary mixed spleen cell cultures. A panel of peritoneal exudate cells (PEC) from mice bearing nonrecombinant and recombinant H-2-Tla haplotypes and their F1 hybrids was used as the source of target and inhibitor cells for direct lytic and competitive inhibition assays. PEC of H-2d and several recombinant haplotypes bearing the d alleles at the D region, including H-2u, were as susceptible to lysis as parental DBA/2 PEC, irrespective of non-N-2 genetic constitution. Those of H-2b, H-2k, H-2s, and recombinant haplotypes not carrying the d allele in the D region were not lysed above the background levels. Syngeneic F1 PEC were not lysed by CTL, but were nevertheless capable of inhibiting the lysis of DBA/2 PEC, albeit slightly less effectively than homozygous Dd-positive PEC inhibitors. Mapping by inhibition assays indicated that the presence of at least one copy of the H-2Dd allele was necessary and was sufficient to confer inhibitory capacity to H-2 heterozygous PEC. These results extend previous observations on primary F1 anti-parental H-2b and H-2k cell-mediated lympholysis (CML) and indicate generality of autoreactive F1 anti-parent CML responses against surface structures coded for or controlled by H-2K or H-2D region genes.