Circulating immune complexes in Sjögren's syndrome.

Circulating immune complexes (IC) in patients with Sjögren's syndrome (SjS) were examined using the 125I-Clq binding method. IC were detected in 52% of the patients, and the highest incidences (80%) of IC were observed in SjS patients with systemic lupus erythematosus (SLE). IC were also demonstrated even in 40% of SjS patients without definite associated diseases. Several systemic manifestations suggesting participation of IC and hypocomplementemia were recognized in these IC-positive patients at the time of assay for IC. The levels of IC were positively correlated with both the erythrocyte sedimentation rate (ESR) and serum gammaglobulin in SjS patients. The incidences of IC increased in patients with severe sialographical changes in their parotid glands. The roles of circulating IC in advancement of the disease as well as in the occurrence of systemic manifestations in this syndrome were proven by the present results.