[Use of serologic reactions for determining the concentration of the determinants of an antigen and its valence].
By the serological tests with the erythrocytic diagnostic agents it is possible to estimate the concentration of the determinants in the antigenic preparation under study. For this purpose it is necessary to have at one's disposal the data on the molecular weight and concentration of the reference antigen, valence of erythrocytes loaded with the antigen or antibodies, and antibody heterogeneity index. If these values are known, then one can calculate the concentration of antigenic determinants in terms divided by the valence of the reference antigen. With the aid of pure antibodies preparation obtained with the immunosorption procedure it is possible to measure the determinant concentration of the antigen tested and the valence of the reference antigen. For the capsular antigen of plaque bacilli the valence was estimated by two independent methods and in both cases it was close to 10. The valence of the reference capsular antigen permits to calculate the concentration of the antibody molecules in the hyperimmune sera without isolation of pure antibodies.