Serum Calprotectin Level in Patients with Systemic Lupus Erythematosus and its Correlation with Disease Activity

Background: Neutrophils contribute to immune defense through phagocytosis and the formation of neutrophil extra-cellular traps (NETs), which can also trigger autoimmunity. Calprotectin (CLP), a key component of NETs, is released during inflammation and plays a role in modulating immune responses. Aim of Study: This study aimed to compare serum CLP levels between systemic lupus erythematosus (SLE) patients and healthy controls, and to assess the relationship between CLP levels and SLE disease activity. Patients and Methods: This cross-sectional study included 41 adult patients diagnosed with SLE and 41 healthy controls. All participants underwent clinical assessment, including com-prehensive medical history and physical examination. Disease activity was measured using the SLE Disease Activity Index 2000 (SLEDAI-2K). Serum CLP levels were measured and compared between patients and controls. Correlations between CLP levels and clinical features of SLE were analyzed, and the diagnostic performance of CLP in distinguishing SLE patients from healthy individuals was evaluated. Results: Serum CLP levels were significantly elevated in SLE patients compared to controls. A significant positive cor-relation was observed with the SLEDAI-2K score (p=0.002). Higher CLP levels were particularly noted in patients with arthritis, cognitive dysfunction, and positive anti-dsDNA an-tibodies. At a cutoff value of 3.45ng/dL, CLP demonstrated robust diagnostic performance, with a sensitivity of 87.8%, specificity of 75.6%, positive predictive value of 78.3%, nega-tive predictive value of 86.1%, and overall accuracy of 87.1%. Conclusion: CLP levels were higher in SLE patients and correlated with disease activity. Levels were elevated in those with arthritis, cognitive impairment, or positive anti-dsDNA, and showed good ability to distinguish SLE from controls.