Enzyme-linked immunosorbent assay of H+,K+-ATPase, the parietal cell antigen.

Vesicular membranes, purified from porcine gastric mucosa and rich in H+,K+-ATPase, were used to establish an enzyme-linked immunosorbent assay (ELISA) for determinations of parietal cell autoantibodies. Results obtained with the ELISA correlated well with standard immunofluorescence determinations of parietal cell antibodies based on frozen sections of rat stomach. The ELISA however was about 10-fold more sensitive than the immunofluorescence method and had high specificity. Intra- and interassay coefficients of variation, determined with a patient sera of average positivity, were 5.5% and 18%, respectively. The ELISA detected antibody binding in 23 out of 26 sera from patients with known autoimmune atrophic gastritis, in five of 25 sera with autoimmune thyroiditis, in five of 20 sera from patients with Graves' disease, in three out of 20 sera from patients with atoxic nodular goitre, in six of 20 sera of patients with primary biliary cirrhosis, in two out of 20 sera of patients with active duodenal ulcer, in two out of 20 sera with detectable antinuclear antibodies, and in one out of 20 sera with detectable rheumatoid factor. Data determined by an ELISA based on a gastric vesicular membrane preparation of human origin correlated well (r = 0.79, P less than 0.001) to those obtained by the standard ELISA based on porcine membrane material. The assay should be well suited for routine determinations of parietal cell antibodies in investigations of autoimmune gastritis and multiple organ autoimmune endocrinopathies.