Platelet serotonin in primary Sjögren's syndrome: level and relation with disease activity.

Primary Sjögren's syndrome (pSS) is chronic autoimmune disorder of unknown ethiopathogenesis. In line with the concept of neuroimmunohormonal dysregulation in inflammatory rheumatic diseases, the aim of this study was to investigate platelet serotonin level (PSL) in patients with pSS and its relation with the activity and duration of the disease. Significantly lower PSL in pSS patients (N=61) was shown as compared to healthy controls (N=103). No correlation was found between PSL and the actual disease activity assessed by the recently developed EULAR Sjögren's Syndrome Disease Activity Index (ESSDAI). Results suggest involvement of the serotonin system in the pathogenesis of pSS.