Prospective study of the immune effects of normalizing the hemoglobin concentration in hemodialysis patients who receive recombinant human erythropoietin.
Partial correction of anemia by erythropoietin improves hemodialysis (HD)-associated immunosuppression. It is not known whether hemoglobin normalization improves immune status further. The authors prospectively compared the immune function of HD patients with congestive heart failure or ischemic heart disease on erythropoietin therapy randomized to normal versus anemic blood hemoglobin concentration. HD patients were randomized into a normal hemoglobin group (n = 17, target hemoglobin of 14 +/- 1 g/dl) or an anemic hemoglobin group (n = 18, target hemoglobin 10 +/- 1 g/dl). Delayed-type hypersensitivity, CD4 and CD8 counts, anti-tetanus toxoid antibody levels, erythrocyte complement receptor 1 expression, and lymphocyte proliferative responsiveness were measured. The observation period was 1 yr, and the trial was open label. Target hemoglobin was achieved and maintained in both groups. Significantly improved cutaneous reactivity was seen in the normal hemoglobin group (P = 0.003). The prevalence of anergy decreased in the normal hemoglobin group (from 60 to 20%) but increased in the anemic hemoglobin group (from 57 to 86%). The anemic hemoglobin group had higher CD8 counts compared with baseline (P = 0.0001) and compared with the normal hemoglobin group (P = 0.038). Both groups had significant increases in tetanus toxoid antibody levels after vaccination but without significant differences between groups. The anemic hemoglobin group had a progressive increase in erythrocyte complement receptor 1 levels compared with baseline (P = 0.002) and relative to the normal hemoglobin group (P = 0.023). There was no consistent pattern of altered proliferative responsiveness of lymphocytes. The data suggest that certain aspects of immune function, particularly delayed-type hypersensitivity, may be improved in HD patients by normalization of hemoglobin through the administration of increased doses of erythropoietin.