Duodenal plasma cells correspond to serum IgA in common variable immunodeficiency.

Common variable immunodeficiency (CVID) can be associated with a range of serum IgA concentrations, from absent, to variably reduced, and in some patients classified as 'possible CVID', even normal. The aim of this study was to assess the proportion of duodenal plasma cells in patients with CVID and determine whether there was an association with serum IgA concentration. Duodenal biopsies obtained at upper endoscopy from 35 patients with CVID were assessed for the presence of plasma cells and compared with serum IgA concentrations. A reduction or absence of duodenal plasma cells in 60% of patients with CVID and an association between the proportions of duodenal plasma cells and serum IgA concentrations was demonstrated. The presence of duodenal plasma cells associated with numbers of isotype switched memory B cells in the peripheral blood. A reduction in serum IgA over time was observed in 19% of CVID patients. The gastrointestinal tract provides a window into the immune system in CVID, and these results reinforce the association between gastrointestinal plasma cells and serum IgA concentrations. Preservation of gastrointestinal plasma cells and serum IgA in some patients with CVID, and the sequential decline of both in others, highlight the heterogeneity of this disorder.