Lyt phenotype of H-2b CTL effectors and precursors specific for the SV40 transplantation rejection antigen.

The immune effector cells mediating the in vitro immune response to the SV40 transplantation rejection antigen were characterized by using monoclonal antibody directed against lymphocyte differentiation (Lyt) antigens. Two distinct T lymphocyte populations were found to be responsible for the in vitro lysis of SV40-transformed cells, and Lyt 1+,2+ cytotoxic T lymphocyte (CTL) that is present in the spleens of SV40 immunized mice 9 days postimmunization and an Lyt 1-,2+ CTL that is generated by secondary in vitro stimulation of in vivo primed spleen cells. During secondary in vitro stimulation of SV40 immune spleen cells obtained 9 days postimmunization, a shift in the Lyt phenotype of the CTL from Lyt 1+,2+ to Lyt 1-,2+ is observed. Although the Lyt 1-,2+ CTL can be derived from Lyt 1-,2+ noncytotoxic memory cells, it is not known whether the Lyt 1+,2+ CTL differentiates into an Lyt 1-,2+ CTL during in vitro stimulation.