Dependence of diffusion coefficients and immunoprecipitating titers on pH: Human serum transferrin, immunoglobulin A, human chorionic somatomammotropin, and their rabbit antibodies

Abstract

The “two-cross” technique, a new two-dimensional immunodiffusion technique, is applied to the study of immunosystems human serum transferrin: a preparation of rabbit antibodies, human serum immunoglobulin A-rabbit antiserum, and human chorionic somatomammotropin-rabbit antiserum. By using this technique it is possible to determine simultaneously the diffusion coefficients and the precipitating titers of the precipitating components and the immunochemical titers of antibody or antisera. The investigations were performed in 0.15 mol dm −3 phosphate-buffered saline solutions in the pH range 5.0–8.6 in 1% (w/v) agarose gel at 20.0 ± 0.1°C. The results obtained for the diffusion coefficients and for the precipitating titers indicated that the reversible self-association of antigens and antibodies with the increasing pH of the medium is accompanied by the decreasing solubility of the precipitating components in the immunoprecipitating system. The changes in immunochemical titers with increasing pH were used to explain the changes in the antigen-to-antibody ratios at equivalency.