Defective repertoire of proliferative T cells during lymphatic regeneration.

Proliferative T cell responses against syngeneic (SMLC) and allogeneic (alloMLC) non-T cells were investigated during the splenic regeneration after an injection of a sublethal dose (300 mg/kg) of cyclophosphamide (Cy). Two days after Cy injection spleen contained no cells capable of proliferative responses. T cells from the regenerating spleens (on day 6-8) had a defective proliferative capacity: the reactivity in the SMLC was at the normal level while alloreactivity was negative. The alloMLC appeared by 14 days after Cy injection, and it was still lower than the alloMLC of the normal splenic T cells. Responding cells of the SMLC in the regenerating phase belonged to the Ly-1+2- cell population: anti-Ly-1 antibody + complement (C) diminished the SMLC by 80%, anti-Ly-2 antibody + C had no effect on the responsiveness of the regenerating T cells. The stimulation of this SMLC was less dependent on splenic adherent cells than the normal SMLC. The significance of these data to the origin of alloreactivity and to the role of the SMLC in the cytotoxic T cell responses are discussed.