An unusual and unreported toxicity to erythropoietin

4. Spriano P. Barosi G, lnvemizzi R, lppoliti G. Fortunato A. Rosso R, Magrini U. Splenomegalic immunocytoma with circulating hairy cells. Report of eight cases and revision of the literature. Haematologica 71:25-33. 1986. 5 . Jansen J, den Ottolander GJ, Schuit HR, Waayer JL, Hijmans W: Hairy cell leukemia: Its place among the chronic B cell leukemias. Semin Oncol I1:386 393. 1984. 6. Sainati L. Matutes E, Mulligan S, de Olivcira MP. Rani S. Lampen IA, Catovsky D: A variant form of hairy cell leukemia resistant to a-interferon: Clinical and phenotypic ChardCtenStiCS of 17 patients. Blood 76:157-162. 1990. 7. Kyle RA, Carton JP: The spectrum of IgM monoclonal gammopathy in 430 cases. Mayo Clin Proc 62:719-731, 1987. 8. Pilarski LM, Andrews EJ. Sema HM. Ledbetter JA. Ruether BA. Mant MJ: Abnormalities in lymphocyte profile and specificity repertoire of patients with Waldenstrom‘s macroglobulinemia, multiple myeloma, and IgM monoclonal gammopathy of undetermined significance. Am J Hematol3053-60, 1989. 9. Cawley CC. Armitage RJ, Worman C P T cell subsets in hairy cell leukemia. Semin Oncol4:4OW8. 1984. 10. Linden MD. Fishleder AJ, Tubbs RR. Park H: lmmunophenotypic spectrum of plasma cell leukemia. Cancer 63:859-862, 1989. and Costa Rica [4]. All individuals failed to demonstrate any clinical or hematological abnormalities, and red blood cell morphology was unremarkable 11-41, Hb Korle-Bu migrates with the Hb S on routine electrophoresis at pH 8.6 and with Hb A in agar electrophoresis at pH 6.0 [ 1-61. This migrating with Hb S may lead to confusion, as in our patient, but additional solubility testing of deoxy Hb should clarify this. since Hb Korle-Bu will give negative results. Hb Korle-Bu has been reported in combination with Hb S 141. It was noted that Hb Korle-Bu behaves much like Hb F in its relative lack of participation in gelation with Hb S [7]. Bookchin et al. [8] reported the first variant with two amino acid substitutions in the same P polypeptide chain and named it Hb C-Harlem; the two substitutions are the same as those present in Hb S and H b Korle-Bu. This newly described Hb variant had sickling properties; however, Hb Korle-Bu mutation appeared to alter the gelation properties and decrease sickling [7-91. Hb Korle-Bu in combination with Hb C has not been reported previously. Our patient is a compound heterozygote for Hb C and for Hb Korle-Bu, a condition that is comparable to a simple Hb C heterozygote. and he should be essentially symptom-free [lo]. One should therefore consider Hb Korle-Bu as an unusual rather than as a clinically abnormal Hb.