Antigenicity of casein enzymatic hydrolysate

An enzymatic hydrolysate of bovine casein were studied for molecular size and antigenic properties. As determined by Sephadex G-25 gel filtration, polypeptide fractions having molecular weights greater than 1,000 were not detected in the soluble fraction of the casein hydrolysate. Antigenicity of the fraction was not detected by heterologous passive cutaneous anaphylaxis in guinea pig-rabbit antiserum system mediated by immunoglobulin G types of antibody (guinea pig passive cutaneous anaphylaxis) and its inhibition test. Furthermore, it was not detected by rat long latency homologous mediated by immunoglobulin E antibody and its inhibition test. To prepare anticasein immunoglobulin E serum for rat long latency homologous passive cutaneous anaphylaxis, immunization of rats was by single subcutaneous injection of casein with aluminum hydroxide. Antiserum with highest passive cutaneous anaphylaxis titer (1:64) against bovine casein was obtained by a dose of 2,000 micrograms of the protein at day 12.