Erythrocyte and glomerular C4d deposits as a biomarker for active lupus nephritis

Abstract

IntroductionLupus nephritis (LN) is a serious manifestation of systemic lupus erythematosus (SLE) and histologically evident even in those without clinical manifestations of renal disease. Aim of the workTo assess C4d on erythrocytes (E-C4d) and glomerular deposits (G-C4d) in SLE patients and study its association to LN and disease activity. Patients and methods: 61 subjects were enrolled including 15 with LN (study group); 15 with renal disease not due to SLE (control A group); 16 SLE patients with no renal affection (control B group) and 15 healthy individuals (control C group). Flow cytometry system was used for C4d immunohistochemical staining. SLE disease activity index (SLEDAI) was assessed for SLE patients. ResultsThe age was comparable among groups; for LN patients was 28.3±8.2years; group A (35.9±13.3); group B (27.1±8.8) and group C (29.4±7.1) (p=.06). Patients were mostly females. The disease duration of LN patients was 1–2years; group A (3–5years) and group B (5–10years). E-C4d and G-C4d deposits were significantly higher in LN patients (8.08±2.93 and 2.3±0.97) in comparison to the control groups (A/B/C) (A: 3.78±0.38 and 0.6±1.12; B: 3.72±0.32; C: 3.55±0.44 p<.001, p<.001, p<.001 MFI respectively). E-C4d and G-C4d significantly correlated with LN activity (r=0.8, p<.001 and r=0.7, p=.005) and with SLEDAI (r=0.9, p=.005 and r=0.8, p=.002, respectively). ConclusionErythrocytic C4d correlated significantly with the LN activity which might serve as a potential biomarker for renal activity in the future instead of biopsy and may further help in the optimum follow up of LN patients.