Reduction of Ovomucoid Immunogenic Activity on Peptic Fragmentation and Heat Denaturation

Three fragments with molecular weights of about 25,000, 18,000 and 13,000 daltons, respectively, were prepared from chicken egg white ovomucoid (MW, 28,000) by peptic limited hydrolysis, and denatured ovomucoid without antigenicity toward anti-ovomucoid antibody was prepared by heating (100 degree C, 30 min, pH 9.0). Mice were immunized by intraperitoneal injection of each preparation in Freund's complete adjuvant, and later they were given 2 booster injections of the antigen mixed with A1(OH) sub(3). The IgE response to each preparation was assayed by the heterologous passive cutaneous anaphylaxis test. The antibody response to fragments or denatured protein was much weaker than that to native ovomucoid, suggesting that either the slight decrease in molecular size or heat denaturation effectively reduces the ovomucoid immunogenic activity.