IL-6 SERUM LEVELS IN RHEUMATOID ARTHRITIS: RELATION TO DISEASE CHARACTERISTICS AND TREATMENT

Purpose: Purpose: Dysregulation of cytokine production plays a central role in the pathogenesis of rheumatoid arthritis (RA). This study aimed to analyse serum levels of IL-6 in patients with RA in relation to clinical and laboratory disease characteristics and treatment regimens. Methods: Serum levels of IL-6 were measured using commercially available ELISA kits in 79 female RA patients and compared to 50 healthy women. Disease activity was assessed by Disease Activity Score-28 with CRP (DAS28-CRP). Patients were stratified into three treatment subgroups: group 1 (n = 26), receiving a low dose of systemic glucocorticoids; group 2 (n = 26), treated with conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs); and group 3 (n = 18), receiving IL-6R inhibitor Tocilizumab (TCZ). Results: Serum IL-6 was significantly higher in female RA patients compared to healthy women (median [IQR]: 8.09 [20.59] pg/ml vs. 0.91 [1.85] pg/ml; p < 0.001). Patients with active disease (DAS28-CRP > 3.2) had markedly higher IL-6 levels than those with low disease activity (DAS28-CRP ≤ 3.2) (p < 0.01). Among treatment groups, TCZ-treated patients exhibited the highest IL-6 levels (17.2 [34.67] pg/ml; p = 0.015). No significant differences in IL-6 levels were observed based on autoantibody status. Conclusions: Our findings demonstrate elevated IL-6 levels in women with active rheumatoid arthritis, supporting the role of IL-6 as a key cytokine in the pathophysiology of this chronic inflammatory disease. Furthermore, the increased IL-6 levels observed during TCZ treatment might reflect ongoing endogenous IL-6 production and persistent disease activity.