SOME CHARACTERISTICS OF CANINE PRECIPITATING AND NON-PRECIPITATING ANTIBODY.

Canine precipitating and non-precipitating antisera against bovine serum albumin were studied by quantitative isotope precipitin and coprecipitation techniques. Canine precipitating antisera yielded curves of incomplete precipitation of antigen in antibody excess. Non-precipitating canine antibody can inhibit precipitation of antigen by rabbit precipitating antibody under certain conditions. Canine precipitating antibody contains a γ-globulin fraction which results in complete precipitation of antigen in antibody excess. It is suggested that canine non-precipitating antibody is a faster moving globulin which is present in canine precipitating antisera and the combined effect of canine non-precipitating and precipitating antibodies results in the characteristic types of canine precipitin curve.