Melatonin in Rheumatoid Arthritis

Synovial Macrophages Show Melatonin Receptors


Address for correspondence: Georges J.M. Maestroni, M.D., Istituto di Patologia, Via in Selva 24, 6601 Locarno, Switzerland. Voice: 0041 91 7562671; fax: 0041 91 752650;


Abstract: The pineal neurohormone melatonin is widely recognized as exerting important immunoenhancing effects that act on specific receptors in immunocompetent cells. This action results in stimulation of cytokine production in lymphocytes and macrophages. Here we report that the nocturnal plasma concentration of melatonin in rheumatoid arthritis (RA) patients is higher than in healthy controls. Furthermore, melatonin is present in the synovial fluid of RA patients and synovial macrophages express a specific binding site. We suggest that melatonin may exert a disease-promoting role in RA.