STUDIES ON NON-PRECIPITATING ANTIBODY

Open Access
Publisher Website
Google Scholar
Abstract
When rabbit antisera are treated at pH 12.6 at 1[degree]C for 6 minutes, circulating antibody-antigen complex precipitates. The regular appearance of large amounts of complex during immunization suggested involvement of non-precipitating antibody in its formation and the possibility that sera may be found which contain free non-precipitating antibody in addition to the antibody bound in the complex. Conversion of this free non-precipitating antibody to a precipitating-like material by the alkali treatment was demonstrated by the following types of experiments (1) when antigen was added to antisera and the precipitates were removed, more antibody-antigen complex nitrogen precipitated from these sera after alkali treatment than from control sera to which no antigen was added. (2) Antisera were depleted of their content of precipitating antibody by addition of antigen. Some sera were also depleted of coprecipitating antibody. They were then treated by alkali and antibody-antigen complex was allowed to separate. Admixture of specific antigen to the ensuing supernates from these alkali treated sera precipitated additional protein nitrogen. No precipitation took place in alkali treated supernates with nonspecific antigen or in untreated supernates with specific antigen. (3) Sera, whether depleted of precipitating and coprecipitating antibody or not, precipitated after alkali treatment more antigen than untreated sera as determined by reaction of the remaining supernates with standardized precipitating antiserum. (4) Alkali treated sera precipitated more radioactivity from Il31 labelled antigen than untreated sera. (5) Gel diffusion analysis showed disappearance of bands in sera depleted of precipitating antibody. Bands of the same mobility reappeared upon alkali treatment.