IMMUNOHISTOCHEMICAL FINDINGS IN JEJUNAL SPECIMENS FROM PATIENTS WITH IGA DEFICIENCY

Jejunal biopsy specimens from 25 patients with IgA deficiency (IgAd) w ere studied immunohistochemically to find markers of inflammation. Fiv e of the 25 patients had coeliac disease (CD): they were on a gluten f ree diet and had normal jejunal morphology. Only two of 15 specimens f rom control subjects had CD25(+) cells in the surface epithelium, whil e 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 lamin a propria of IgAd patients. The median percentage of crypt cells in mi tosis (Ki67(+) cells) was higher in the specimens from IgAd patients ( 26%) than in those from controls (13%, p<0.001). The densities of gamm a delta T cell receptor positive cells in the surface epithelium and l amina propria did not differ in the specimens from IgAd patients and t hose of controls nor was the expression of HLA class II antigens augme nted in the surface epithelium. These findings were similar for the Ig Ad patients whether or not the patient had DQB 0201 allele, a genetic marker which is strongly associated with CD. The inadequacy of the loc al 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.