Spontaneous rosette formation of rat thymus cells with guinea pig erythrocytes.

C57 black mice were immunised intraperitoneally with a DBA2 lymphoma (SL2). Fourteen days later spleen cells were prepared. These cells lysed the specific target (SL2) in vitro. Spleen cells were cultured for 24 hr at 37 ° C. Cell-free culture supernatants contained IgG and lysed SL2 cells either in the presence of a source of complement or in the presence of a monolayer of macrophages (a good source of antibody-dependent effectors). The cells producing cell-dependent antibody adhered to nylon wool and were unaffected by anti-theta serum. It was found that the production of antibody in vitro did not make a significant contribution to the observed cytolysis of SL2 by sensitised spleen cells. This effect was mediated by thymus-derived lymphocytes.