Human antibodies to bovine alpha-globulin.

Antibodies to bovine gamma-globulin (anti-BGG antibodies) were detectable by a radio-immunoassay in 70% of healthy blood donors but, generally, the titres were low. Significantly increased concentrations of anti-BGG antibodies were found in patients lacking IgA but not in patients with allergic disorders. The anti-BGG antibodies were shown to give rise to falsely high IgE values in the radio-immunosorbent test for IgE determination (RIST) when a sheep anti-IgE antiserum was used. Furthermore, falsely positive results can sometimes be caused by such antibodies in the determination of cow-dander- or cow's-milk-specific IgE by the radio-allergosorbent test (RAST). When a rabbit anti-IgE antiserum was used instead of the sheep anti-IgE, normal IgE levels and negative RAST results were obtained. The difference is explained by the higher degree of cross-reactivity between the anti-BGG antibodies and sheep alpha-globulin than between anti-BGG antibodies and rabbit alpha-globulin.