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Publisher: Peytchinski Publishing Ltd.
ISSN: 1312-773X (Online)
Issue: 2026, vol. 32, issue1
Subject Area: Medicine
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DOI: 10.5272/jimab.2026321.6703
Published online: 23 January 2026
Original article
J of IMAB. 2026 Jan-Mar;32(1):6703-6707
IL-6 SERUM LEVELS IN RHEUMATOID ARTHRITIS: RELATION TO DISEASE CHARACTERISTICS AND TREATMENT
Viktoria Vasileva1, 2
, Georgi Vasilev3, Mariana Ivanova4, Lyuba Miteva1, Irena Manolova1,
1) Department of Molecular Biology, Immunology and Medical Genetics, Medical Faculty, Trakia University, Stara Zagora.
2) Clinical laboratory, Trakia Hospital, Stara Zagora.
3) Laboratory Haematopathology аnd Immunology, National Specialised Hospital for Active Treatment of Haematological Diseases, Sofia, Bulgaria.
4) Clinic of Rheumatology, University Hospital "St. Ivan Rilski", Medical University of Sofia, Bulgaria.
ABSTRACT:
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.
Keywords: IL-6, rheumatoid arthritis, disease activity, therapy,
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Please cite this article as: Vasileva V, Vasilev G, Ivanova M, Miteva L, Manolova I. IL-6 Serum Levels in Rheumatoid Arthritis: Relation to Disease Characteristics and Treatment. J of IMAB. 2026 Jan-Mar;32(1):6703-6707. [Crossref - 10.5272/jimab.2026321.6703]
Correspondence to: Viktoria Vasileva, Department of Molecular Biology, Immunology and Medical Genetics, Medical Faculty, Trakia University, Stara Zagora; 11, Armeiska Str., Stara Zagora 6000, Bulgaria; E-mail: dr.viktoriya.vasileva@trakia-uni.bg
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Received: 09 July 2025
Published online: 23 January 2026