[Antigenic determinants on ovalbumin and ovomucoid: comparison of the specificity of IgG and IgE antibodies]

Abstract

To delineate the antigenic determinants on ovalbumin (OA) and ovomucoid (OVM) recognized by specific IgG and IgE antibodies in sera from patients with allergy to hen's egg, we studied the binding activities of IgG and IgE antibodies to native OA or OVM and seven different OA or OVM preparations, i.e. heated OA or OVM (100 degrees C for 3 min and 80 degrees C for 30 min) or 0.3 M NaOH, dithiothreitol (DTT), sodium dodecyl sulfate (SDS), 6 M urea or HCl treated OA or OVM. Eight patients with IgE anti-OA antibodies and 12 patients with IgE anti-OVM antibodies were used in these studies. The binding activities of IgG and IgE antibodies to physically or chemically denatured OA were partially decreased compared with those to native OA, whereas IgG and IgE antibodies in sera from patients bound well to denatured OVM with similar binding activities to native OVM. These results strongly suggest that antibodies to OA recognize partially conformational antigenic determinants on OA, whereas antibodies to OVM mainly recognize sequential antigenic determinants on OVM, and that antigenic determinants of OVM recognized by antibodies in sera from patients are more stable than those of OA under these denaturation conditions. In addition, the binding activities of IgE antibodies to denatured OA or OVM were significantly different from those of IgG antibodies to these OA or OVM, suggesting that the specificities of IgE antibodies to OA or OVM may be different from those of IgG antibodies to OA or OVM.