Elevated CD71 Expression on CD4⁺ T Cells in Egyptian SLE Patients: A Potential Biomarker for Disease Activity and Renal Involvement

Background: Systemic Lupus Erythematosus (SLE) is a chronic autoimmune disease characterized by multisystem involvement and immune dysregulation. Recent studies suggest that iron metabolism, particularly through CD71 (transferrin receptor), has a essential role in disease pathogenesis. Objective: To quantify CD71 expression on CD4⁺ T cells in Egyptian SLE patients and evaluate its correlation with disease activity and organ involvement. Methods: A case-control study was conducted involving 30 SLE patients and 30 matched healthy controls. CD71 expression has been measured via flow cytometry. Clinical and laboratory data were analyzed to assess correlations with disease activity and organ-specific manifestations. Results: CD71 expression was significantly raised in SLE cases (19.6 ± 9.8) compared to controls (2.3 ± 0.7, p < 0.001). A strong positive correlation was observed with SLEDAI (r = 0.97, p < 0.001) and renal involvement (p = 0.008). Conclusion: Elevated CD71 expression may be a novel indicator of illness activity, severity, and renal pathology in SLE. Its expression reflects immune activation and may guide future therapeutic strategies.