Serum Interleukin-6 in Systemic Lupus Erythematosus: Insights into Immune Dysregulation, Disease Activity, and Clinical Manifestations

Background: Interleukin-6 (IL-6) is a multifunctional cytokine implicated in various inflammatory and immune-mediated processes. Its involvement in systemic lupus erythematosus (SLE) has been increasingly investigated, particularly related to disease activity and tissue damage. This study aimed to quantify serum IL-6 levels in patients with SLE and assess their associations with clinical manifestations and laboratory parameters. Methods: A total of 88 patients diagnosed with SLE and 87 matched healthy controls were included. Serum IL-6 concentrations were measured by ELISA. Clinical data, SLEDAI scores, organ involvement, inflammatory markers, and autoantibody profiles were recorded. The statistical analysis involved non-parametric testing, correlation analysis, and linear regression. Results: IL-6 concentrations were higher in SLE patients than in controls (7.46 ± 6.73 vs. 5.30 ± 10.89 pg/mL). Significantly increased IL-6 levels were observed in patients with active disease (SLEDAI ≥ 6; p = 0.025) and renal (p = 0.001) involvement. Positive correlations were identified between IL-6 and ESR, creatinine, ANA, and specific autoantibodies (anti-dsDNA, SSA, and SSB). IL-6 also correlated with IL-10 (p = 0.010) but showed no significant association with IL-17A, TNF-α, CRP, or complement levels. Conclusions: Elevated IL-6 levels are associated with greater disease activity and specific organ involvement in SLE. These findings highlight IL-6 as a measurable indicator of immunological and clinical disease expression, supporting its relevance in disease monitoring.