Online Articles: Clinical and Laboratory ObservationsAnti-M Antibody Induced Prolonged Anemia Following Hemolytic Disease of the Newborn Due to Erythropoietic Suppression in 2 SiblingsIshida, Atsushi MD*; Ohto, Hitoshi MD, PhD†; Yasuda, Hiroyasu MT, PhD†; Negishi, Yutaka MD*; Tsuiki, Hideki MD, PhD*; Arakawa, Takeshi MD*; Yagi, Yoshihito MT‡; Uchimura, Daisuke MT§; Miyazaki, Toru MT§; Ohashi, Wataru MT§; Takamoto, Shigeru MD, PhD§Author Information *Department of Pediatrics ‡Division of Central Laboratories, Gifu Prefectural Tajimi Hospital, Gifu †Department of Blood Transfusion and Transplantation Immunology, Fukushima Medical University, Fukushima §Japanese Red Cross Hokkaido Block Blood Center, Hokkaido, Japan Parental consent was granted for all tests. The authors declare no conflict of interest. Reprints: Atsushi Ishida, MD, Department of Pediatrics, Gifu Prefectural Tajimi Hospital, 5-161, Maehata-cho, Tajimi City, Gifu 507-8522, Japan (e-mail: firstname.lastname@example.org). Received September 19, 2014 Accepted March 26, 2015 Journal of Pediatric Hematology/Oncology: August 2015 - Volume 37 - Issue 6 - p e375-e377 doi: 10.1097/MPH.0000000000000341 Buy Metrics Abstract Hemolytic disease of the newborn (HDN) arising from MNSs incompatibility is rare, with few reports of prolonged anemia and reticulocytopenia following HDN. We report the younger of 2 male siblings, both of whom had anti-M-induced HDN and anemia persisting for over a month. Peripheral reticulocytes remained inappropriately low for the degree of anemia, and they needed multiple red cell transfusions. Viral infections were ruled out. Corticosteroids were given for suspected pure red cell aplasia. Anemia and reticulocytopenia subsequently improved. Colony-forming unit erythroid assay revealed erythropoietic suppression of M antigen-positive erythroid precursor cells cultured with maternal or infant sera containing anti-M. In conclusion, maternal anti-M caused HDN and prolonged anemia by erythropoietic suppression in 2 siblings. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.