Serum Concentrations of Cytokines in Patients With Restless Legs Syndrome

Several data suggested a possible role of inflammatory factors in restless legs syndrome (RLS). In this regard, the results of a limited number of studies assessing serum or plasma levels of cytokines have been inconclusive. To investigate the possible role of several cytokines (tumour necrosis factor α-TNF-α, and interleukins-IL-1α, IL-1β, IL-6 and IL-10) as markers of idiopathic RLS (iRLS), we have measured their serum levels in a large series of iRLS patients and controls. We assessed serum levels of TNF-α, IL-1α, IL-1β, IL-6 and IL-10 in 100 patients diagnosed with iRLS and 110 age- and sex-matched healthy controls using a monoclonal Enzyme-Linked ImmunoSorbent Assay (ELISA) method. Serum levels of IL-1α and IL-1β were below detection limits both in iRLS patients and controls. Serum TNF-α, IL-6 and IL-10 levels did not differ significantly between iRLS patients and controls in the whole series, although TNF-α levels were lower in male iRLS patients compared with male iRLS controls. Serum TNF-α, IL-6 and IL-10 levels were not correlated with age at onset and severity of RLS. The data from the current study suggest that serum levels of the cytokines studied cannot be considered useful markers of iRLS.