NON-PRECIPITATING RABBIT ANTIBODIES - STUDY OF THEIR REACTIVITY IN VITRO BY MEANS OF QUANTITATIVE PRECIPITIN AND TANNIC ACID HAEMAGGLUTINATION TECHNIQUES

Abstract

Incomplete antibodies of the co-precipitating type were "unmasked" from the antisera of rabbits immunized with ovalbumin (EA) and bovine plasma albumin (BPA) by absorption of the precipitins with successive small additions of the homologous antigen. Extensive quantitative immunochemical studies of systems containing homologous antigen and varying ratios of incomplete: complete antibodies indicated (1) that the non-precipitating antibodies were able to delay but not inhibit the combination between homologous antigen and precipitating antibody and (2) that in the BPA-anti-BPA system complete co-precipitation was obtained when the ratio of incomplete: complete antibody was as high as 1:2, whereas in the EA-anti-EA system this ratio was only 1:5. When studied by means of the tannic acid haemagglutination technique the non-precipitating antibodies in question were not found to be active as agglutinins. The results are compatible with the concept of the univalence of non-precipitating antibodies, and are compared with those obtained in similar studies with artificially produced incomplete antibodies.