Salivary glands of patients with Sjögren's syndrome (SS) have been shown to be a site of anti-SS-B/La antibody production. The present study investigated differences in the localization of the SS-B/La antigen in labial salivary gland (LSG) tissue between SS and non-SS patients, which may explain the local antigen-driven anti-SS-B/La response.
Distribution of SS-B/La was studied immunohistologically in the LSG biopsy samples of 9 SS patients, 10 non-SS patients, and in normal tissues obtained at autopsy within 2 hours after death, using a mouse monoclonal antibody directed to SS-B/La. In 3 SS and 3 non-SS patients, LSGs were also studied with affinity-purified biotinylated human antibodies directed against SS-B/La.
In the non-SS patients, SS-B/La was primarily observed in the nucleoli of acinic cells of the LSGs. Patients with either primary SS or secondary SS showed an accumulation of SS-B/La in the nucleoplasm of acinic cells. In the SS patients, SS-B/La was also detected in the cytoplasm as a diffuse or perinuclear staining. Sometimes, SS-B/La was found along the membrane of acinic cells as well. This aberrant nuclear and cytoplasmic distribution of SS-B/La in SS patients correlated well with abnormalities in the composition of the plasma cell population in the LSGs, but not with a lymphocytic focus score > 1.
The accumulation and redistribution of SS-B/La in the LSGs may play an important role in the local antigen-driven anti-SS-B/La response in SS, and can also be used to improve the diagnostic possibilities of the LSG biopsy.