Evaluating the roles of interleukin-17, C3, C4, antinuclear antibody, and antiphospholipid antibody in the pathophysiology of systemic lupus erythematosus

Abstract

Introduction and aim. Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by immune dysregulation, autoantibody (Abs) production, and complement (C) consumption. This study aimed to evaluate the diagnostic and prognostic relevance of antinuclear antibodies (ANA), interleukin (IL)-17A, complement components C3 and C4, and antiphospholipid (APL) Abs in patients to SLE compared with healthy individuals. This study provides an assessment of these biomarkers within a single cohort of an Iraqi population, addressing a regional knowledge gap. Material and methods. A prospective case–control study was conducted in Al-Nasiriyah, Iraq, from July 2024 to July 2025, including 110 patients with SLE and 70 apparently healthy individuals. Serum levels of ANA, IL-17A, complement C3, complement C4 and APL immunoglobulin (Ig) M and G were measured using enzyme-linked immunosorbent assay (ELISA) and nephelometry. Statistical analyzes were included using descriptive statistics, chi-square tests, t-tests, and correlation analyses. Results. Patients with SLE showed significantly higher levels of ANA, IL-17A, and APL Abs, along with significantly lower levels of complement C3 and C4. ANA was positively correlated with IL-17A and APL Abs and negatively with complement components. There were also significant negative correlations of APL-IgM/IgG with C3 and C4, while IL-17A did not show a correlation with C3 or C4. Conclusion. These findings demonstrate coordinated immune activation and complement depletion in SLE and emphasize the value of combined biomarker evaluation within a context of a population of the Middle East specifically.