The Influence of Non-Specific Protein on the Heat Inactivation of Antibody to Pneumococcal Polysaccharide

The electrophoretic patterns of casein and of the antibody to Type I pneumococcal polysaccharide were practically unaltered by heat treatment of the individual solutions. Heat treatment of a mixture of these two substances led to loss of precipitability of the antibody by the homologous polysaccharide and to a change in the electrophoretic pattern. Part of the alpha casein and part of the antibody (gamma globulin) migrated with the beta casein after heat treatment; this change appeared to result from interaction of the two constituents after partial denaturation. The interaction was probably responsible for the inactivation. Precipitative tests on the fractions separated by electrophoresis of the unheated mixture afforded additional evidence that alpha casein is the constituent responsible for the inactivation of the antibody. By electrophoretic fractionation of the heated mixture it was possible to separate the antibody of unchanged mobility from that which had been modified by heat treatment. Under these conditions the unchanged antibody was still precipitable by polysaccharide.