Anti-cytoplasmic autoantibodies reactive with epithelial cells of the salivary gland in sera from patients with Sjogren's syndrome: their disease- and organ-specificities

To test whether the autoantibodies reactive with epithelial cells of the sa livary gland in sera from Sjogren's syndrome (SS) patients are specific for the organ and the disease, tissue reactivities of serum IgG obtained from the patients with SS and oral lichen planus (OLP), another immune-mediated oral mucosal disease, were examined by immunohistochemistry and Western blo tting. IgG purified from the sera of SS patients specifically localized not only on the nuclei but also on the cytoplasm of the salivary gland epithel ial cells. On the other hand, no convincing staining of the epithelial cell s was observed when IgG purified from the sera of OLP patients or those fro m healthy controls were used for immunohistochemistry. No cytoplasmic stain ing was observed when sections of kidneys and pancreas were stained with SS patients' IgG. In Western blotting performed by using lysates of a submand ibular gland as antigens, all the IgG prepared from the SS patients reacted prominently with several protein bands, including those specific for the d isease and the organ. These results suggest that production of autoantibodi es reacting with the cytoplasm of salivary gland epithelial cells is a char acteristic of SS, and may play a role in the pathogenesis of the sialadenit is.