Humoral Immunity to Dietary Antigens in Healthy Adults

Abstract

The occurrence of antibodies to 5 dietary protein antigens in the sera from 21 healthy adults was investigated by a modified Farr assay. Antibody to ovalbumin (OA) occurred most frequently (90%); only 24% had antibodies to .alpha.-lactalbumin (ALA). No correlation was noted between the titer of antibodies against bovine serum albumin (BSA) and OA in the single individual. The avidity constants (108-109 l/mol) and cross-reactivities against other albumins of anti-BSA antibodies in 2 human sera were comparable to that of the antibodies in pooled hyperimmune rabbit antiserum. Crossed radioimmunoelectrophoresis showed serum anti-BSA and anti-OA antibodies to be predominantly of the IgG class (13/13, 10/10), occasionally of the IgA- (6/13, 1/10) and rarely of the IgM class (1/13, 0/10). Analysis by radioelectroimmunoassay (rocket immunoelectrophoresis) of the IgG subclass distribution of anti-BSA and anti-OA antibodies showed total absence of IgG3. In contrast, antibodies of the IgG4 subclass were frequently present even in sera with very low levels of total IgG4.