Comparison of the residual allergenic activity of six different hydrolyzed protein formulas.

The residual allergenic activity of protein hydrolysates contained in marketed "hypoallergenic" infant formulas can be determined both by in vivo methods (skin prick tests, provocation tests) and by in vitro methods (radioallergosorbent test, radioallergosorbent inhibition, crossed radioimmunoelectrophoresis, basophil histamine release). In general, whey hydrolysates containing a high percentage of larger peptides have the highest capacity to induce positive skin test and provocation test results, and to bind to human serum IgE antibodies of cow milk-sensitive children. Casein hydrolysates appear to have very little residual allergenic activity. Before hypoallergenic formulas are prescribed for cow milk-sensitive children, individual testing (e.g., skin test, challenge tests) is recommended.