Selective IgA deficiency and Crohn's disease: report of two cases.

Two patients are described with Crohn's disease and selective IgA deficiency. Serum IgA was undetectable in each case, and immunoperoxidase studies of the lamina propria showed a gross diminution of IgA-bearing plasma cells. Peripheral blood lymphocytes, however, showed normal numbers of IgA-bearing lymphocytes. The typical clinical course and histology in these two patients suggest that IgA-mediated responses in the mucosa are not involved in the pathogenesis of Crohn's disease.