The quantitation of IgG4 antibodies to three common food allergens by ELISA with monoclonal anti-IgG4.

Enzyme-linked immunosorbent assays, capable of detecting nanogram quantities of IgG4 to 3 common food allergens, have been developed with use of a monoclonal anti-human IgG4. Calibrated positive human sera were used to construct standard curves. The allergens employed, major protein constituents of egg (ovalbumin), milk (beta-lactoglobulin) and-wheat (gluten), were highly effective in coating microtitre plate wells; and the assays proved to be sensitive, reproducible and specific, in terms of both allergen and IgG subclass. On testing sera from a group of non-allergic individuals a high proportion were found to contain IgG4 antibodies to the 3 allergens. A pool of 60 sera obtained from blood donors also contained IgG4 antibodies to all 3 allergens. The results illustrate that IgG4 antibodies against common food constituents are frequently encountered in sera from normal individuals; and that this needs to be taken into consideration in assessing the possible role of such antibodies in immediate hypersensitivity reactions.