The participation of complement in the parietal cell antigen-antibody reaction in pernicious anaemia and atrophic gastritis.

Indirect evidence suggests that the parietal cell antibody circulating in the serum of pernicious anaemia patients is a complement fixing antibody. In this work, we have presented direct evidence using an immunofluorescent technique, that the antigen–antibody union occurring in the gastric mucosa between this antibody and the parietal cell antigen binds complement (C'). We have further adduced data to indicate that serum C' activity was decreased in more than one-third of our patients with pernicious anaemia and in one-fourth of those with advanced atrophic gastritis. Eighty-five per cent of the patients with lowered serum C' had parietal cell antibody in the serum and some of them also had intrinsic factor antibody. These findings support the concept of the autoimmune mechanism in the development of the gastric atrophic lesion in a proportion of patients with pernicious anaemia and atrophic gastritis. This mechanism includes the participation of complement in the antigen–antibody reaction at the parietal cell level.