T cell-mediated cytotoxic immune responsiveness of chimeric mice bearing a thymus graft fully allogeneic to the graft of lymphoid stem cells.

Fully allogeneic, chimeric mice were established by adult thymectomy of (A x B) F1 animals, grafting parental A-type thymus under the kidney capsula, followed by lethal (900 rd) irradiation and reconstitution with B parental-type bone marrow cells treated with xenogeneic anti-T cell antiserum plus complement. Following in vivo sensitization with inactivated Sendai virus (SV) suspensions, no virus-specific T cells could be detected within the spleen cells of the mice. Upon stimulation with third-party allogenic cells in a primary mixed lymphocyte culture, spleen cells of all animals generated alloreactive cytotoxic T lymphocytes (CLT). More interestingly, upon secondary in vitro stimulation with inactivated SV-conjugated B-type stimulator cells, B-type-restricted, virus-specific CTL were inducible in each case. Upon restimulation with SV-conjugated A-type stimulator cells, A being the H-2 type of the grafted thymus, T cells of some but no all mice generated A-type-restricted, virus-specific CTL. The data suggest that in allogeneic, chimeric mice virus-specific CTL can be induced. Moreover, virus-specific CTL, restricted to the H-2 type of the lymphoid stem cell inoculum, are more readily inducible than those restricted to the H-2 type of the allogeneic thymus.