Weight Estimates of Rabbit Anti-Human Serum Albumin Based on Antigen-Binding and Precipitin Analyses: Specific Hemagglutinating Activities of 7 S and 19 S Components

Abstract

The modified antigen-binding capacity (mABC) procedure has been applied to assays of different antibody functions in rabbit antisera to human serum albumin. Sera taken during the first 18 days after one injection of antigen in the hind toe-pads possess small amounts of 19 S immunoglobulins, which have high hemagglutinating potencies, but which do not mediate passive cutaneous anaphylaxis in the guinea pig. The same sera also possess greater quantities of 7 S immunoglobulins, with feeble hemagglutinating properties but with marked precipitating, antigen-binding and anaphylactogenic activities. The mABC assays have frequently yielded higher antibody levels than were obtained in specific precipitation, suggesting the presence of nonprecipitating antibodies, whose existence has also been demonstrated in coprecipitation experiments.