High circulating levels of soluble scavenger receptors (sCD5 and sCD6) in patients with primary Sjogren's syndrome

Objective. To determine the existence of circulating levels of soluble scav enger receptors (sCD5 and sCD6) in patients with primary Sjogren's syndrome (SS), and to analyse the correlation with clinical and immunological featu res of SS. Methods. Ninety consecutive patients with primary SS were studied. All pati ents fulfilled four or more of the European diagnostic criteria for SS. sCD 5 and sCD6 levels were determined using a specific enzyme-linked immunosorb ent assay (ELISA) developed in our laboratory. Results. Detectable levels of sCD5 were found in 39 (43%) SS patients. The mean +/- standard error values of sCD5 were 3.5 +/-0.5 ng/ml for patients w ith SS and 1.9 +/-0.1 ng/ml for healthy blood donors (P <0.001). We found h igher levels of sCD5 in patients with hypocomplementaemia (6.5 vs 3.5 ng/ml , P=0.03) and cryoglobulinaemia (6.9 vs 2.6 ng/ml, P=0.001). On the other h and, detectable levels of sCD6 were found in 60 (67%) SS patients. The mean +/- standard error values of sCD6 were 25.5 +/-7.8 ng/ml in SS patients an d 5.27 +/-1.40 ng/ml in healthy blood donors (P=0.01). When the sCD6 levels were compared according to the presence or absence of immunological featur es, patients with cryoglobulinaemia showed higher levels of circulating sCD 6 (77.3 vs 17 ng/ml, P=0.01) than those without cryoglobulinaemia. Conclusion. Patients with primary SS showed higher levels of circulating sC D5 and sCD6 when compared with controls. Moreover, the existence of some im munological features (hypocomplementaemia and cryoglobulinaemia) was associ ated with high levels of both soluble scavenger receptors. These facts may reflect an enhanced lymphocytic activation in patients with primary SS.