Measurement of IgE Antibody by an Antigen-Binding Assay: Correlation with PK Activity and IgG and IgA Antibodies to Allergens

Abstract

A quantitative radioimmunoassay for IgE antibodies (ab) is described. The assay measures IgE antigen-binding activity (BA) by using purified allergens radiolabeled with ¹²⁵I, IgE myeloma serum as a source of carrier protein, and monospecific goat anti-IgE (anti-IgE) to precipitate the IgE. IgE BA for the Group I protein of rye grass pollen (Rye I) was measured in the serum of patients with grass pollen hay fever who had never received immunotherapy. Values for IgE BA were found to correlate well with radioallergosorbent technique (RAST) results (r_s = 0.89, p IgE BA > IgA BA (geometric mean values 862, 214, and 60.2 units/ml, respectively). In keeping with this there was a highly significant quantitative correlation between IgG BA and IgE BA (r = 0.72, p<0.001). None of the sera from nonallergic persons contained detectable IgA or IgE BA for Rye I; however, 20% of these sera (10 of 48) contained IgG BA.