Clinical relevance of antibodies against serotonin and gangliosides in patients with primary fibromyalgia syndrome.

The fibromyalgia syndrome (FMS) is a non-articular rheumatic disorder associated with disturbances in serotonin metabolism. In order to evaluate whether patients with FMS suffer from an autoimmune disorder, we tested sera from 50 clinically well-defined FMS patients for non-organ-specific and organ-specific antibodies by enzyme-linked immunosorbent assay and immunofluorescence test. Common antibodies against nuclei, mitochondria, and microsomes were not increased in these patients compared to healthy controls. However, 74% had antibodies against serotonin and gangliosides. The clinical and diagnostic relevance of these antibodies is supported by the absence of anti-serotonin antibodies in other rheumatic disorders such as rheumatoid arthritis, polymyalgia rheumatica, and collagen diseases. These antibodies may belong to the group of antireceptor antibodies, considering the fact that gangliosides are an important component of the serotonin receptor. It remains to be determined whether these antibodies are of pathogenetic relevance, interfering with serotonin binding and thereby inducing symptoms associated with FMS.