title: Prophylactic red blood cell exchange for prevention of severe immune hemolysis in minor ABO-mismatched allogeneic peripheral blood progenitor cell transplantation after reduced-intensity conditioning.
abstract: BACKGROUND
  Delayed severe immune hemolysis due to donor-derived passenger lymphocytes is observed in minor and/or bidirectional ABO-mismatched transplants, especially after reduced-intensity conditioning (RIC). The incidence is reported in up to 30 percent of patients and can result in multiorgan failure (MOF) and death.
  
  
  METHODS
  A first group of 32 patients (historical control) underwent RIC followed by allogeneic hematopoietic peripheral blood progenitor cell transplantation at our institution. In 5 of 10 patients with a minor and/or bidirectional ABO-mismatched graft, severe immune hemolysis was observed, leading to death in 3 of them. Therefore, we initiated a protocol with prophylactic red blood cell (RBC) exchange in minor and/or bidirectional ABO mismatch of a second group of patients (study group) and investigated the incidence of hemolysis, transplant-related mortality (TRM), and overall survival (OS) and compared these data with the historical control group. Twenty-two of 80 patients in the study group had a minor and/or bidirectional ABO-mismatched donor.
  
  
  RESULTS
  In 20 patients, a prophylactic RBC exchange was performed. Three patients showed mild to moderate citrate reactions, and in 1 patient the procedure had to be stopped because of hypotension. Eighteen of 20 patients engrafted uneventfully, 1 patient rejected his graft, and another 1 showed signs of mild hemolysis. In the minor and/or bidirectional ABO-mismatched setting patients in the study group had a lower risk for TRM at 1 year compared to patients in the historical control group (16% vs. 53%, p < 0.05) and a better 1-year OS (65% vs. 40%, p < 0.05).
  
  
  CONCLUSIONS
  RBC exchange is a safe procedure, reducing the incidence of delayed severe immune hemolysis and thus the risk of TRM in minor and/or bidirectional ABO-mismatched cases.
authors.affiliation: Department for Blood Group Serology and Transfusion Medicine, First Medical Department, Bone Marrow Transplantation, Medical University of Vienna, Wāhringer Gürtel 18-20, A-1090 Vienna, Austria. nina.worel@meduniwien.ac.at
authors.forename: Nina
authors.initials: N
authors.lastname: Worel
authors.forename: Hildegard T
authors.initials: HT
authors.lastname: Greinix
authors.forename: Volker
authors.initials: V
authors.lastname: Supper
authors.forename: Gerda
authors.initials: G
authors.lastname: Leitner
authors.forename: Margit
authors.initials: M
authors.lastname: Mitterbauer
authors.forename: Werner
authors.initials: W
authors.lastname: Rabitsch
authors.forename: Gottfried
authors.initials: G
authors.lastname: Fischer
authors.forename: Agathe
authors.initials: A
authors.lastname: Rosenmayr
authors.forename: Paul
authors.initials: P
authors.lastname: Höcker
authors.forename: Peter
authors.initials: P
authors.lastname: Kalhs
mesh_terms: D000017:ABO Blood-Group System / Q000276:immunology*; D000293:Adolescent; D000328:Adult; D000368:Aged; D001787:Blood Group Incompatibility / Q000097:blood*; D017707:Erythrocyte Transfusion; D005078:Exchange Transfusion, Whole Blood; D005260:Female; D006086:Graft vs Host Disease / Q000209:etiology; D006461:Hemolysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D036102:Peripheral Blood Stem Cell Transplantation / Q000009:adverse effects* / Q000401:mortality; D019172:Transplantation Conditioning / Q000379:methods*; D014184:Transplantation, Homologous
chemical_list: D000017:ABO Blood-Group System