IMMUNOPATHOLOGY OF SJOGRENS-SYNDROME

Sjogren's syndrome is a chronic autoimmune disorder characterized by m ononuclear cell infiltration around epithelial cells of exocrine gland s. In recent years, several studies have tried to elucidate the compon ents of the immunopathologic interaction in Sjogren's syndrome as well as the function of these components. The majority of the mononuclear infiltrating cells are CD4 positive T lymphocytes (60-70 %) whereas B cells constitute one fourth of the infiltrating cells. Macrophages and natural killer cells are poorly represented in the lesion. Epithelial cells of minor salivary glands of patients with Sjogren's syndrome ex press several cytokines (IL-1 beta, IL-6, NO), protooncogenes (c-myc), autoantigens (Re, La, Fodrin) and costimulatory molecules (B71, B72). The characteristic destruction of epithelial cells of Sjogren's syndr ome patients is probably due to activation of several apoptotic pathwa ys since epithelial cells express different apoptosis related molecule s such as Pas, Fast, Bar, while mononuclear cells express Perforin and Granzymes. Finally epithelial cells seem to exert a regenerative effo rt since they express trefoil proteins (pS2). The above mentioned prop erties give epithelial cells the leading role in the pathophysiology o f the syndrome but the exact causative agent which drives the immune s ystem towards an autoimmune reaction still remains obscure.