Recombinant human erythropoietin modulates erythrocyte complement receptor 1 functional activity in patients with lupus nephritis

Deposition of immune complexes (IC) is an important step in the pathogenesis of lupus nephritis. Impairment of IC-clearance contributes to the accumulation of IC. It may be partly attributed to decreased complement containing immune complex (ICC) binding by erythrocytic complement receptor I (ECR I ). Stimulating erythropoiesis with recombinant human erythropoietin (rHuEPO) may enhance the IC-clearance as increasing ECRI expression and/or functional activity. Ten anemic patients with lupus nephritis were treated with 50 IU rHuEPO (Eprex) per kg body weigth three times a week during a five week period. ICC-binding capacity of ECR1 was determined with 125 I-labelled, C3ib containing BSA-anti-BSA complexes. In addition to effective correction of anemia, indicated by increased red blood cell count (RBC), hemoglobin concentration and reticulocyte ratio, rHuEPO significantly improved decreased ECRI functional (ICC-binding) activity in patients with lupus nephritis. This improvement correlated with the increase in reticulocyte ratio. Although patients were kept on their previous therapy during Eprex administration, their clinical condition also improved. That was shown by a decrease in Westergreen ratio, serum creatinine concentration and anti-dsDNA level and also by an increase in creatinine clearance. Results suggest a beneficial immune modulatory effect of rHuEPO in lupus nephritis.