Gliadin IgG subclass antibodies in patients with coeliac disease.

We have measured IgG1, 2, 3 and 4 subclass antibodies to gliadin and casein in normal controls, treated and untreated coeliac patients. The amount of antibody in each subclass was determined separately as a titre and as a concentration, by reference to a standard curve. Both methods of quantitation, carried out in separate assays, yielded comparable results (IgG antibody r = 0.86, IgG1 antibody r = 0.89). In all the coeliac patients, the majority of antibody was IgG1, and little IgG2, 3, 4 antibody was detected. Untreated coeliac patients had higher titres of IgG and IgG1 antibodies to gliadin and casein compared with normal controls. In the treated coeliac patients compared with the normal controls, there was no significant difference between the titres of IgG and IgG1 antibodies to gliadin but there were higher titres to casein.