Immune cells and functions in patients with restless legs syndrome

Restless legs syndrome (RLS) is a sleep-related disorder, and some evidence suggests that inflammation contributes to its pathophysiology. This study aimed to investigate the relationship between RLS and immune cells. Fourteen RLS patients, and 10 healthy subjects were included in the study. The percentages of T, B, natural killer (NK), natural killer T (NKT) and innate lymphoid cells (ILCs) were analyzed, along with intracellular levels of interferon-gamma (IFN-γ), interleukin (IL)-6, IL-10, and IL-13 in T, B and NK cells. Additionally, CD8⁺ T and NK cell cytotoxic activities were assessed using flow cytometry. Plasma levels of IFN-γ, tumor necrosis factor-alpha (TNF-α), IL-2, IL-4, IL-6, IL-10, and IL-13 were evaluated with bead-based soluble molecule assay. Compared to healthy subjects, the ratio of ILC-1 subset and IL-13⁺CD4⁺ T cells were significantly increased in RLS patients, while the levels of ILC-2 subset were significantly decreased. When the NK cell cytotoxic activity of RLS patients was evaluated, it was found that the NK cell perforin levels were lower than healthy subjects. Plasma IL-13 levels were also significantly elevated in RLS patients compared to healthy individuals. These findings suggest that both innate and adaptive immune responses may play a role in RLS pathophysiology. Alterations in ILC subsets, along with elevated IL-13, IL-10, and IL-6 levels, as well as NK and CD8⁺ T cell cytotoxic activity, indicate that immune dysregulation might contribute to the disease mechanism. Furthermore, the observed correlation between efficient sleep and immune markers highlights the potential role of immune system modulation in RLS management.