IMMUNOHISTOCHEMICAL FINDINGS IN JEJUNAL SPECIMENS FROM PATIENTS WITH IGA DEFICIENCY

Jejunal biopsy specimens from 25 patients with IgA deficiency (IgAd) were studied immunohistochemically to find markers of inflammation. Five of the 25 patients had coeliac disease (CD): they were on a gluten free diet and had normal jejunal morphology. Only two of 15 specimens from control subjects had CD25(+) cells in the surface epithelium, while this was seen in 19 out of 20 specimens from IgAd patients (p<0.0001). A significant increase of CD25(+) cells was also noted in the lamina propria of IgAd patients. The median percentage of crypt cells in mitosis (Ki67(+) cells) was higher in the specimens from IgAd patients (26%) than in those from controls (13%, p<0.001). The densities of gamma delta T cell receptor positive cells in the surface epithelium and lamina propria did not differ in the specimens from IgAd patients and those of controls nor was the expression of HLA class II antigens augmented in the surface epithelium. These findings were similar for the IgAd patients whether or not the patient had DQB 0201 allele, a genetic marker which is strongly associated with CD. The inadequacy of the local immunoglobulins in patients with IgAd may lead to increased T cell activation, which is accompanied by the appearance of intraepithelial CD25(+) cells and with an increase in the mitotic rate in the crypts.