Target determinants for F₁ hybrid anti-parental H-2(d) 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-TIa 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-2(d) and several recombinant haplotypes bearing the d alleles at the D region, including H-2(u), were as susceptible to lysis as parental DBA/2 PEC, irrespective of non-N-2 genetic constitution. Those of H-2(b), H-2(k), H-2(s), and recombinant haplotypes not carrying the d allele in the D region were not lysed above the background levels. Syngeneic F₁ PEC was not lysed by CTL, but were nevertheless capable of inhibiting the lysis of DBA/2 PEC, albeit slightly less effectively than homozygous D(d)-positive PEC inhibitors. Mapping by inhibition assays indicated that the presence of at least one copy of the H-2D(d) 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-2(b) and H-2(k) 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.