H-2 Unrestricted cytotoxic T cell activity against antigens controlled by genes in the QA/TLA region

The specificity of H-2 unrestricted cytotoxic T cells was analyzed in secondary CML responses. A/J strain effector cells, sensitized against A. Tla(b) lymphoid cells, lysed target cells from strains with differing H-2 haplotypes but all sharing Qa-1(b)/Tla(b) alleles; whereas, target cells from strains with Qa-1(a)/Tla(a) were not. When B6.Tla(a) animals were in vivo-primed and challenged in vitro with B6 stimulator cells, no cytotoxic effector cell activity was generated. However, if B6.Tla(a) animals were primed in vivo with A.BY cells and then rechallenged in vitro with either A.BY or B6 stimulator cells, cytotoxic effector cells were generated that lysed target cells from strains with Qa-1(b)/Tla(b) alleles. This suggests that factors in addition to Qa/Tla may play a role in the generation of anti-Qa/Tla effector cell activity. It was also noted that targets from strains with Qa-1(a)/Tla(a) alleles were killed, although to a much lesser extent than the Qa-1(b)/Tla(b) targets. SWR anti-DBA/1 effector cells strongly lysed target cells from strains with Ga-1(b)/Tla(b), lysed Qa-1(a)/Tla(a) targets to a lesser extent, and produced no cytolytic effect on B6.Tla(a) target cells. These data suggest that in addition to a CML target antigen associated with Qa-1(b)/Tla(b), there may be an additional specificity recognized by cytotoxic T cells controlled by a gene outside of Qa-1(b)/Tla(b).