Human gastric H,K-adenosine triphosphatase beta-subunit is a major autoantigen in atrophic corpus gastritis. Expression of the recombinant human glycoprotein in insect cells.

Abstract

Sera from patients with atrophic corpus gastritis with pernicious anemia frequently contain parietal cell autoantibodies. We have previously demonstrated that the human H,K-adenosine triphosphatase (H,K-ATPase) alpha-subunit constitutes a major autoantigen. The present study investigates whether the human H,K-ATPase beta-subunit is an autoantigen, too, The gene of the human beta-subunit was expressed in insect cells by a baculovirus expression system. The reactivity of sera from 42 patients towards the recombinant glycoprotein was analyzed by means of an enzyme-linked immunosorbent assay. Thirty-nine of the 42 sera (93%) scored positive. Autoantibody binding in 41 sera (98%) was eliminated when unglycosylated beta-subunit was used as antigen, and antibody binding in the last serum was decreased by 30%. The results indicate that the beta-subunit is indeed a major autoantigen and that carbohydrates are involved in binding of the autoantibodies.