Selective induction of OX19+ (CD5+) or OX19- (CD5-) alloreactive cytolytic lymphocytes in the rat.

The phenotypes of alloselective cytolytic lymphocytes of the rat are defined by staining of peritoneal cells of alloimmunized donors with monoclonal antibodies, sorting in a cytofluorometer and evaluating cytolytic capacity in a 51Cr-release assay. We demonstrate that alloimmunization of BN rats can result in either OX19+ (CD5+) or OX19- (CD5-) cytolytic alloselective lymphocytes and show that the OX19- (CD5-) cytolytic cells are OX34+ W3/25- (CD4-) OX8+ (CD8+) lymphocytes not exposing surface Ig. It is further demonstrated that the appearance of CD5+ and CD5- cytolytic alloselective lymphocytes are mutually exclusive; immunization with (WF X BN) F1 cells leading exclusively to appearance of OX19+ effector cells while immunization with WF cells leads to OX19- effector cells. Alloimmunization of WF rats only results in appearance of OX19+ cytolytic lymphocytes.