Qed‐1 – a target for unrestricted killing by T cells

Two prototype target determinants for unrestricted killing by T cells are defined: Qed‐l^a, detected on B6.Tla^a targets by C3H/HeJ lymphocytes primed in vivo and restimulated in vitro by B 10.BR spleen cells; and Qed‐1^b, detected on C57BL/6J lymphocytes by B 10.BR anti‐C 3 HiHeJ effector cells generated in the same manner. Other mouse strains can be typed for Qed‐1 by the ability of their lymphocytes to inhibit one of these lytic reactions. Of 55 inbred strains, 52 expressed either Qed‐1^a or Qed‐1^b, which thus behaved as products of alleles of a single locus, Qed‐1. The remaining three strains, all H‐2^r, did not compete against specific lysis of Qed‐1^a, but inhibited Qed‐1^b‐specific lysis only in part; it is proposed that these strains carry a third allele or haplotype, Qed‐1^c. The Qed‐1 locus was mapped distal to Qa‐2. Qed‐1^h was found on both normal and mitogen‐activated lymphocytes and did not appear confined to any lymphoid subpopulation. Cytotoxic responses, not restricted by H‐2 and specific for antigens controlled by the Tla region, could be induced in several combinations of H‐Zidentical strains differing at Qed‐1. Cells of some strains, like B 10.BR, NZB, and SWR, responded directly in culture, even without priming in vivo.