IgG subclasses to food proteins in atopic and normal individuals.

IgG subclass antibodies to ovalbumin (OVA), gliadin (GLI) and beta-lactoglobulin (beta-lac) were determined in 18 atopic subjects and 18 age- and sex-matched controls. IgG antibodies to OVA and GLI were found predominantly as IgG4 subclass, with the IgG antibodies to beta-lac distributed evenly between IgG2, IgG3 and IgG4 in both groups. The proportion of anti-OVA IgG antibodies in the IgG3 subclass was significantly higher in the atopic group (22%) than in the nonatopic group (8%: p < 0.001). The proportion of anti-GLI IgG3 antibodies was also higher in the atopic group (43%) than the nonatopic group (24%: p < 0.001). OVA subclass antibodies in the atopic and nonatopic subjects were mainly IgG4, and GLI subclass antibodies were mainly IgG3 and IgG4. This study provides information on the distribution of IgG subclasses to food proteins, and in particular those related to protein GLI. The importance of IgG3 subclasses in atopic disease is highlighted; this phenomenon, to our knowledge, has not previously been reported.