Determination of IgG subclass antibodies against wheat flour antigens by an ELISA technique

We describe the assay conditions for an enzyme‐linked immunoassay for the determination of IgG and IgG subclass antibodies in serum to water‐soluble wheat flour antigens. The optimal antigen coating concentration was 5 μg/ml for total IgG, IgG1, IgG4 and 100 μg/ml for IgG2. Serial dilutions of test sera were used and commercially available monoclonal mouse anti‐human IgG isotype antibodies (as ascites fluid) were diluted 1:500–1:1000. Specific wheat flour antibodies belonging to the IgG1, IgG2 and IgG4 subclasses were detected. Despite the lack of standardized isotype‐specific second mouse monoclonal antibodies, the subclass antibody levels between flour‐exposed bakers and controls could be compared. We observed significantly higher IgG1, IgG2 and IgG4 subclass antibodies among 23 bakers than among 12 non‐exposed controls, but no IgG3 antibodies were detected. The differences in biological activities of the IgG subclass antibodies may explain the clinical and pathophysiological features for flour‐induced occupational allergic diseases among bakers.