IN-VIVO AND IN-VITRO EXPRESSION OF ADHESION MOLECULES BY PERIPHERAL-BLOOD LYMPHOCYTES FROM PATIENTS WITH PRIMARY SJOGRENS-SYNDROME - CULTURE-ASSOCIATED ENHANCEMENT OF LECAM-1 AND CD44

The interaction of adhesion receptors on lymphocytes with their ligands over endothelial cells provides the mechanism by which lymphocytes infiltrate target tissues in autoimmune diseases. Primary Sjogren's syndrome (SS) is associated with lymphocytic infiltration in exocrine glands. The aim of this study was to examine levels of expression of adhesion molecules by peripheral blood lymphocytes from patients with SS (before and after stimulation). Peripheral blood lymphocytes from 16 patients with primary SS and from 15 controls were stained directly or cultured for 72 h with and without phytohaemagglutinin (PHA). Indirect immunofluorescence with monoclonal antibodies and flow cytometry were used. The following molecules were detected in patients before culture: CD18 (mean percentage 94%), CD11a (94%), CD11b (39%), CD54 (23%), CD58 (62%), CD44 (Hermes-1; 82%), CD49-d (VLA-4; 80%), CD25 (11%) and LECAM-1 (62%). After stimulation with PHA, there was an increase in the levels of CD18 (2.5-fold), CD11a (2.3-fold), CD54 (10.2-fold), CD58 (2.5-fold), CD44 (2.4-fold), CD49d (3.4-fold) and CD25 (62-fold) on lymphocytes from both patients and controls. The number of positive cells and level of expression did not differ from the controls, except in the case of unstimulated, cultured lymphocytes in which the levels of CD44 and LECAM-1 were increased more in patients than in normal controls. The increase in the level of in vitro expression of CD44 (P<0.05) and LECAM-1 (P<0.002) on lymphocytes from patients with primary SS reached statistical significance when compared to similarly cultured lymphocytes from controls. The regulation of LECAM-1 and CD44 expression in patients with SS may contribute to the immunopathogenesis of this desease by increased tethering or rolling (early adhesive events) of lymphocytes over endothelial cells. Such molecules may be involved in lymphocytic homing to tissues in SS.