To evaluate the effect of hydroxychloroquine treatment on interleukin 6 (IL6), hyaluronic acid (HA), and soluble interleukin 2 receptor (sIL2R) concentrations in the saliva and serum of patients with primary Sjögren's syndrome (SS).

Fourteen SS patients treated with hydroxychloroquine 200 mg/day for 12 months were investigated in an open prospective study. Clinical parameters of efficacy and routine biochemical and haematological data to assess drug safety and tolerability were determined every three months. Salivary and serum IL6, sIL2R, and HA values were determined at study entry, 6 and 12 months, using ELISA and radiometric assays.

After hydroxychloroquine treatment, salivary IL6 concentrations decreased from 13.2 (1.2) to 7.3 (1.1) pg/ml (mean (SEM)) (p < 0.0001). Similarly, salivary HA concentrations were also reduced from 577.8 (120) to 200 (34) ng/ml (mean (SEM) (p < 0.003). Serum IL6 concentrations decreased from 5.4 (0.6) to 2.9 (0.2) pg/ml (mean (SEM) (p < 0.001), while serum HA concentrations remained unchanged. No change has been detected in salivary or serum sIL2R concentrations after 12 months of treatment with hydroxychloroquine. Treatment also resulted in significant reduction in erythrocyte sedimentation rate, serum gamma globulin, and C reactive protein values while only partial clinical improvement was noted in some patients. A more pronounced decrease of salivary IL6 and HA levels was found in the two patients in whom a reduction in the swelling of the parotid gland was noted.

In this open label study of hydroxychloroquine treatment for SS a significant reduction of some salivary inflammatory markers was seen at the end of 12 months. Although during the treatment period only a partial clinical effect could be noted, the findings suggest that a double blind controlled study of hydroxychloroquine in SS is indicated.