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Pure red‐cell aplasia caused by the antibody to recombinant erythropoietin, epoetin‐β, in a Japanese patient with chronic renal failure

A 68‐year‐old male with chronic renal failure and anemia received recombinant human erythropoietin (rHuEPO), epoetin beta, for approximately 1 year. Although the agent was initially effective for improving anemia, anemia refractory to EPO administration appeared and then worsened later, and pure red‐cell aplasia (PRCA) was diagnosed. Anti‐EPO antibody was detected by radioimmunoprecipitation (RIP) assay in the patient's serum. The antibody inhibited the proliferation of EPO‐dependent cell line in a dose‐dependent manner neutralizing EPO activity. The antibody also reacted with the other epoetin alfa products. The antibody did not recognize the carbohydrate moieties or denatured epoetin beta. The result suggested that the antibody recognized the conformational epitope of epoetin beta peptide molecule. Withdrawal of EPO and administration of cyclosporine decreased the titers of antibody; however, erythroid progenitor has not yet regenerated although the requirement for red blood cell transfusion is decreasing. Am. J. Hematol. 78:15–20, 2005. © 2004 Wiley‐Liss, Inc.