COMPLEMENT ACTIVATION IN PATIENTS WITH PRIMARY SJOGRENS-SYNDROME - ANINDICATOR OF SYSTEMIC-DISEASE

Sixteen patients with primary Sjogren's syndrome, verified according t o the Copenhagen criteria, were investigated for evidence of complemen t activation. Thirteen of the patients had intact functional activity of both the classical and alternative pathways, with normal concentrat ions of the complement proteins C1q, C1s, C3, C4 and the complement pr otein fragments C2a and C3d in the circulation. In contrast, three pat ients showed clear evidence of complement activation. Further investig ation of these patients revealed manifestations of glomerulonephritis, vasculitis and primary biliary cirrhosis. Six months later, one patie nt developed a malignant non-Hodgkin lymphoma. We conclude that comple ment activation is generally not associated with primary Sjogren's syn drome. Evidence of complement activation in patients considered to hav e primary Sjogren's syndrome should raise the suspicion of concomitant systemic disease and/or extraglandular activity.