Small intestinal plasma cells in coeliac disease.

Using a modified immunoperoxidase technique to achieve optimum staining and reproducible counts of plasma cells in paraffin embedded tissue, IgA, IgM, IgE, and IgG plasma cells were studied in small bowel biopsies from 20 controls, 23 untreated coeliac patients, 19 treated coeliac patients, and seven patients with Crohn's disease not involving duodenum or jejunum. In controls the ratio of the mean counts for IgA, IgM, IgE, and IgG plasma cells was 2.5:1:1:1 respectively. In patients with untreated coeliac disease, counts of all types of plasma cell were significantly increased approximately two-fold compared with controls although for IgG cells there was considerable overlap. The ratio of the mean plasma cell counts in the untreated coeliac patients was 3.5:1.5:2:1. Counts fell significantly after treatment with a gluten-free diet. There was no significant difference between counts in the controls and the Crohn's disease patients. The changes found in coeliac disease may simply be a non-specific response to mucosal damage. The increases in IgA and IgM plasma cells, however, suggest that the deposits of extracellular IgA and IgM observed in coeliac mucosa are locally produced, and the increase in IgE plasma cells raises the possibility that reaginic type hypersensitivity may be involved in coeliac disease.