Aberrant expression pattern of the SS‐B/La antigen in the labial salivary glands of patients with Sjögren's syndrome

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Abstract
Objective. 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. Methods. 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. Results. 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. Conclusion. 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.