Allergen-Binding Activity of γE, γG and γA Antibodies in Sera from Atopic Patients

Abstract

The antibodies associated with γG-, γA-, γM- and γE-globulins in the sera of ragweed sensitive patients were titrated by radioimmunodiffusion using I¹³¹-labeled antigen E and rabbit antibodies specific for each of these immunoglobulins. Quantitative measurements of the allergen-binding activities of the γG, γA and γE antibodies in the specimens were made by precipitation of the radioactive allergen-antibody complexes with rabbit antibodies. The titer of the antibodies in the radioimmunodiffusion method paralleled their allergen-binding activities. The skin-sensitizing activity of the patients' sera, which was determined by Prausnitz-Küstner reactions with antigen E, correlated with the allergen-binding activity of γE antibody but not with that of γG or γA antibodies. γM antibody was not detected in most of the samples containing high reaginic activity. Precipitation of γE-globulin removed the skin-sensitizing activity of the sera. These findings support the hypothesis that the reaginic antibody is associated with γE-globulin. The minimum dose of the skin-sensitizing antibody required for giving positive Prausnitz-Küstner reactions was estimated. Comparisons were made between the γE antibody in patients' sera and rabbit antibody specific for antigen E, with respect to the allergen-binding activity. The binding activity of γE antibody present in the minimum dose of five patients' sera required for giving positive reactions was comparable to that of 2 × 10^-6 µgN of the rabbit antibody.