Preferential recognition of primary protein structures of alpha-casein by IgG and IgE antibodies of patients with milk allergy.

We studied the binding activities of IgE and IgG antibodies in patients with allergy to cow milk proteins, against different alpha-casein preparations: alpha-casein treated with urea, hydrochloric acid, sodium hydroxide, or sodium dodecyl sulfate (SDS); or heat-denatured alpha-casein. The binding activities of IgE and IgG antibodies to these denatured alpha-casein preparations were compared with those to native alpha-casein. The binding activities of IgE and IgG antibodies to these denatured alpha-casein preparations were similar to those to native alpha-casein although the binding activities of IgG antibodies to these denatured alpha-casein preparations were relatively heterogeneous compared with those of IgE antibodies. Since modifications of alpha-casein did not alter the ability of alpha-casein to react with these antibodies, IgE and IgG antibodies to alpha-casein in sera from patients with allergy preferentially bind to the antigenic determinants associated with primary protein structures.