Medical Progress: PDF OnlyEastham Edmund J.; Lichauco, Tom; Pang, Kam; Walker, W. AllanJournal of Pediatric Gastroenterology and Nutrition: 1982 - p 23-28 Free Abstract Summary The relative antigenicity of whey fractions from milk, milk formula, soy-based formula, and formula containing protein hydrolysate were compared by tanned hemagglutination and immunoprecipitation techniques. A significantly lower antibody response to representative cow's milk proteins (casein, bovine serum albumin, boxine -y-globulin. and a-lactalbumin) occurred in animals fed with milk formula compared to cow's milk, suggesting that these antigens had been modified during the preparation of the milk-based formula. Antibody responses to protein in soy formulas were equivalent to the response to cow's milk protein, suggesting that soy proteins are as antigenic as milk proteins. The response with time to soy protein separated from crude soy powder had a gradual slope and was lower than those to formula, suggesting that the processing of crude soy powder may enhance its antigenicity. In contrast, the antibody response was negative to milk proteins from protein hydrolysate formula, suggesting no antigenicity of this special formula. Furthermore, prior oral feeding with milk formula resulted in a state of partial systemic immunological tolerance. This was even more prolonged using soy-based formula. These data may explain why although as antigenic, soy-based formulas are clinically hypoallergenic-a more complete “low-zone” tolerance being achieved by oral exposure. It is speculated that the handling of ingested soy proteins by the immunological system results in a hypoallergenic state by stimulation of specific suppressor T cells in Peyer s patches by the hapten effect of partially digested protein fragments or by effector cell blockade due to immune complexes present in slight antigen excess. Future work in this area will give pediatricians a sounder scientific basis on which to give advice about infant feeding practices. © Lippincott-Raven Publishers.