Usefulness of initial histological features for stratifying Sjogren's syndrome responders to mizoribine therapy

Objectives. To evaluate the response of patients with SS to mizoribine therapy in relation to histological features of minor salivary glands. Methods. Forty patients definitely diagnosed as having SS were treated with mizoribine (150 mg/day). Thirty-four untreated patients matched for age, baseline salivary secretion, etc., served as controls. Salivary secretion volume (measured by the Saxon test) and serum IgG level were measured before and after 24 weeks of treatment. Each histological finding (lymphocytic infiltration, acinar atrophy and intralobular fibrosis) was graded at baseline and the therapeutic responses were compared with the grade at 24 weeks in both the groups. Results. There was a significant increase of the salivary secretion volume after treatment with mizoribine as compared with the untreated control group. The effect of mizoribine on salivary secretion was more marked in patients having moderate lymphocytic infiltration and moderate or less severe acinar atrophy and intralobular fibrosis at baseline. Conclusions. Mizoribine was clinically effective in patients with SS whose minor salivary glands had moderate cell infiltration and were free of intralobular fibrosis. The drug was less effective in patients who presented intralobular fibrosis. Histological evaluation of the minor salivary glands may serve to predict the response of SS patients to mizoribine therapy.