Role of renal expression of CD68 in the long-term prognosis of proliferative lupus nephritis

Introduction Renal histology of proliferative lupus nephritis (LN) shows increased macrophage infiltration, but its association with renal outcome is a matter of debate. Here, we investigate the potential relationship that macrophage expression has with renal prognosis in patients with proliferative LN. Methods Fifty patients newly diagnosed with proliferative LN were followed for a median of 8 years. Laboratory testing was conducted at diagnosis, after induction therapy and at the final follow-up evaluation. Renal biopsies were obtained at diagnosis and underwent immunohistochemical analysis with anti-CD68 and monocyte chemoattractant protein 1 monoclonal antibodies. Patients were stratified at final follow-up evaluation into glomerular filtration rate (GFR) > 60 ml/min/1.73 m(2) (non-progressor group; n = 24) and GFR <= 60 ml/min/1.73 m(2) (progressor group; n = 26). All patients were treated with prednisone and six pulses of cyclophosphamide on induction therapy. Conventional maintenance therapy was administered in both groups. Results Compared to progressors, the non-progressor group showed a lower chronicity index (p = 0.01) and fewer CD68-positive cells in the renal tubules (p = 0.01) and particularly in the renal interstitium (p = 0.0003). Baseline and final serum creatinine correlated positively with the chronicity index (r = 0.3, p = 0.01 and r = 0.3, p = 0.04, respectively), and final serum creatinine correlated positively with interstitial expression of CD68 (r = 0.4, p = 0.0006). Conclusion Renal expression of CD68 and the chronicity index are associated with progression to chronic kidney disease in patients with proliferative LN.