IgE antibodies to peptic and peptic-tryptic digests of betalactoglobulin: significance in food hypersensitivity.

The sera of 20 atopic patients, 10 with hypersensitivity symptoms upon ingestion of milk and 10 without such symptoms, were tested by a radioimmunoassay for the detection of IgE antibodies to whole bovine milk, betalactoglobulin (BL), enzymatic digests of BL and fractions thereof. While only 4/10 patients had IgE antibodies to undigested BL all 10 patients had IgE antibodies to BL digests. All controls gave negative results. These findings suggest that enzymatic digestion of BL may yield antigenic fractions which elicit IgE antibodies and that these antibodies would be missed if the undigested food protein were to be used solely in testing.