THE IGA SUBCLASS DISTRIBUTIONS OF ENDOMYSIUM AND GLIADIN ANTIBODIES IN HUMAN SERA ARE DIFFERENT

Subclass distributions of total IgA, IgA gliadin antibodies and IgA en domysium antibodies were investigated in 26 sera of patients with coel iac disease or dermatitis herpetiformis by means of enzyme immunoassay and fluorescence microscopy. Eight-point-three percent of total IgA b elonged to the IgA(2) subclass. The fraction of IgA(2) gliadin antibod ies amounted to 30.6% of IgA gliadin antibodies and was significantly different from the proportion of total IgA(2). The relative percentage of IgA(2) endomysium antibodies was very close to that of total IgA(2 ) in serum (6.2%) and significantly lower than that of IgA(2) gliadin antibodies. The results suggest an intestinal origin of gliadin antibo dies. Different subclass distribution of IEA endomysium antibodies may be due to extraintestinal production or to the different nature of th e endomysium antigen eliciting a more prominent IgA(1) response than g liadin.