Secretory component, α1‐antitrypsin and lysozyme in IgA deficient children. An immunohistochemical evaluation of intestinal mucosa

Abstract

Nine children with IgA deficiency were studied in order to evaluate by the immunoperoxidase technique the behaviour of secretory component (SC), α₁-antitrypsin (α₁-AT), lysozyme and esterase in biopsies of intestinal mucosa. In none of the studied patients was SC found to be lacking, suggesting that the epithelial transport mechanism of IgA across enterocytes was relatively normal. The distribution of SC activity in immunodeficient children differed however from that seen in control intestinal mucosa in its non-uniform distribution on the villus, abnormal retention in the Golgi region of enterocytes or exclusive activity confined to the proliferating compartment of the villus. The staining of α₁-AT in enterocytes was clearly obvious in all studied cases with no alteration in zonal distribution when compared with normal human mucosa. The lysozyme staining pattern was seen exclusively in Paneth cells. The non-specific esterase positive enterocytes observed in control mucosa failed to stain in biopsies from IgA deficient children. The results of this study of SC, α₁-AT, lysozyme and esterase may indicate that IgA deficiency is not related to a defect in enterocyte transport of immunoglobulins and confirms previously reported findings indicating the lymphoid B-cell compartment to be altered.