B-Lymphocyte Mediated Cytolysis: A Complement Independent Phenomenon

Abstract

Spleen cell suspensions from C₅₇BI mice immunized intraperitoneally with sheep erythrocytes were highly cytotoxic towards the erythrocytes in vitro. The cytolysis was specific: human type ‘O’ erythrocytes were not lysed. Cytolysis was inhibited when the interacting cells were incubated in the presence of anti-K or anti-γ1 plus anti-γ2 antisera. Pre-treatment of the immune spleen cells with anti-immunoglobulin antisera in hhe presence or absence of complement completely inhibited their subsequent cytolytic activity, but had no effect on plaque-forming cell numbers. The cytolytic activity was unaffected by the removal of θ-antigen bearing cells or of glass-adherent cells (presumably macrophages). In contrast, the lysis of DBA/2 mastocytoma cells by immune C₅₇B1 lymphocytes was unaffected by treatment with any of the anti-immunoglobulin reagents. The lytic activity of the spleen cell suspensions towards the mastocytoma cells was completely abolished by removal of θ-antigen bearing cells. Both the B-cell mediated cytolysis of erythrocytes and the T-cell lysis of mastocytoma cells appeared to proceed independently of the complement system. Lysis in both cases was unaffected by the presence of an excess of antisera monospecific for complement components C₂, C₃ and C₅.