Properties of guinea pig 7S antibodies. III. Identification of antibodies involved in complement fixation and hemolysis.

Guinea pig 7Sgamma(2) antibodies were demonstrated to fix complement in the presence of antigen and to sensitize antigen-coated, tanned erythrocytes for lysis in the presence of complement; guinea pig 7Sgamma(1) antibodies did not participate in these reactions. Gamma-2 antibodies were more efficient in provoking hemorrhagic necrosis in reverse passive Arthus reactions than equal amounts of non-complement-fixing gamma-1 antibodies. Unlike anaphylaxis in the guinea pig, both guinea pig 7Sgamma(1) and 7Sgamma(2) antibodies provoked passive cutaneous anaphylactic reactions in the rat. Efficient hemolytic activity attributable to 7S guinea pig anti-sheep erythrocyte antibodies migrated faster than the peak of complement-fixing activity, but slower than the peak of PCA activity in starch block electrophoresis. It is uncertain whether this activity is a function of a third type of antibody produced in response to the particulate property of the antigen or whether it is due to the antigenic heterogeneity of the erythrocyte cell membrane.