Studies on the Mechanism of Immune Cytolysis

Abstract

Abstract Sheep erythrocytes (E) and mouse mammary tumor cells (MM102) were sensitized with F(ab′)2 antibodies which had been prepared by pepsin digestion after passage through a Sepharose column coupled with anti-Fc to remove intact IgG. Those cells were lyzed at the incubation with rabbit serum (RaS) or guinea pig serum (GPS). Since E-F(ab′)2 did not fix C1 (E-F(ab′)2 was incubated with purified C1, and the fixed C1 to the cells was examined with C1 transfer to EAC4) and did not react with 125I-anti-Fc, the possibility was excluded that intact IgG antibodies had been remaining in the F(ab′)2 fraction. However no hemolysis of E-F(ab′)2 was observed at the incubation with C4-deficient GPS. To examine the effect of natural antibody, E, E-IgG (slightly sensitized) as well as E-F(ab′)2 were treated with EDTA-serum and the cells were incubated with 1/40 GPS after washing with GVB++. By the treatment with EDTA-serum, the hemolysis of E-F(ab′)2 was remarkably enhanced.