The occurrence of auto-antibodies in patients with gastro-duodenal lesions.

The occurrence of auto-antibodies in patients with the autoimmune disease pernicious anaemia and in patients with active duodenal ulcers was investigated. In order to characterize antigenic structures, various cellular and subcellular fractions were prepared from pig gastric mucosa and from a homogenate of duodenal mucosa. By means of an enzyme-linked immunosorbent assay and immunoblotting, both the H+,K(+)-ATPase and pepsinogen/pepsin were shown to constitute the major antigens. All of the seven pernicious-anaemia sera that were tested contained auto-antibodies against both antigens, and the epitopes of the H+,K(+)-ATPase were shown to be localized on its cytoplasmic face. In 75% (18/24) of the sera from patients with duodenal ulcers, auto-antibodies were detected when using purified antigens. Six sera reacted with H+,K(+)-ATPase and twelve reacted with pepsinogen, one reacted with both antigens, and four sera reacted with the duodenal mucosal antigen. The occurrence of auto-antibodies indicates that there is a mucosal lesion and that immunological factors may be involved in the pathogenesis of the disease in some patients.