Background: One of the immunobiological factors thought to have modulatory effects in rheumatoid arthritis [RA] is interleukin-41 [IL-41], a recently identified cytokine claimed to be up-regulated in RA patients.
The aim of the work: The objective of our research was to assess IL-41 level in the serum of patients with RA and to assess its association with the activity of the disease.
Patients and Methods: There were 51 patients with rheumatoid arthritis who participated in the study and 46 healthy controls. The erythrocyte sedimentation rate [ESR], C-reactive protein [CRP], rheumatoid factor [RF], and anti-cyclic citrullinated peptide [anti-CCP] were among the indicators that were evaluated. Additionally, the Disease Activity Score [DAS28] was assessed and an enzyme-linked immunosorbent assay [ELISA] was used to determine serum levels of IL-41.
Results: Patients with RA had elevated serum IL-41 levels relative to controls [479.8 ±61.4 pg/mL vs. 260.9±39.7 pg/mL, respectively; P < 0.001]. In the RA group, IL-41 exhibited a negative correlation with platelet count [PLT] [r = -0.3258, p = 0.0411] and a positive correlation with DAS28 [r = 0.3142, p = 0.0045], ESR [r = 0.3944, p = 0.0034], and CRP [r = 0.3486, p = 0.0249]. Serum IL-41 levels showed no relationship with RF or anti-CCP. The diagnostic value of IL-41 for RA was estimated using the ROC curve analysis. The area under curve [AUC] was 0.745 with 71.88 % sensitivity and 68.21 % specificity, and the cut-off value for IL-41 in RA was 316.048 pg/mL [p < 0.001].
Conclusion:  Rheumatoid arthritis and associated disease activity markers are strongly correlated with increased serum IL-41 levels in rheumatoid arthritis patients.