title: Alloimmunization in sickle cell anemia in the era of extended red cell typing.
abstract: BACKGROUND
  Red blood cell (RBC) transfusion remains an essential part of the management of patients with sickle cell disease (SCD). Alloimmunization is a major complication of transfusions. Extended RBC typing is advocated as a means to reduce alloimmunization in SCD. Our goal was to assess alloimmunization among individuals with SCD at our center since implementing extended RBC typing.
  
  
  METHODS
  We reviewed electronic medical records of all patients with SCD (N = 641) in our comprehensive SCD Program to determine transfusion histories. Cross-referencing with our blood bank database, we extracted data such as antibodies identified, detection date and genotyping in specific cases. Transfusion sources were determined for those with C, E, and Kell antibodies.
  
  
  RESULTS
  Of 180 patients transfused from 2002 to 2011, 26 developed at least one new antibody. The majority of alloimmunized patients (14/26) received episodic transfusions only. The most common antibodies formed were against C and E antigens. Of the 16 patients who developed C, E, Kell antibodies, nine had one or more documented transfusions at an outside hospital. Five patients had Rh variants undetectable on routine phenotyping including two novel e alleles related to ceAR and ce(S)(733G).
  
  
  CONCLUSIONS
  Despite extended RBC typing, alloimmunization may still occur due to RBC variants that are not detected on routine screening and transfusions at institutions where extended RBC typing is not done. Extended RBC typing should be the standard of care for patients with SCD. Prospective genotyping may reduce allosensitization to rare variants not detected on routine screening.
authors.affiliation: Division of Hematology, Oncology and Stem Cell Transplant, Ann and Robert H. Lurie Children's Hospital of Chicago, Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA.
authors.forename: Chibuzo
authors.initials: C
authors.lastname: O'Suoji
authors.forename: Robert I
authors.initials: RI
authors.lastname: Liem
authors.forename: A Kyle
authors.initials: AK
authors.lastname: Mack
authors.forename: Paris
authors.initials: P
authors.lastname: Kingsberry
authors.forename: Glenn
authors.initials: G
authors.lastname: Ramsey
authors.forename: Alexis A
authors.initials: AA
authors.lastname: Thompson
mesh_terms: D000328:Adult; D000755:Anemia, Sickle Cell / Q000097:blood / Q000276:immunology / Q000628:therapy; D001789:Blood Group Antigens / Q000097:blood / Q000276:immunology; D001787:Blood Group Incompatibility / Q000097:blood / Q000276:immunology; D001788:Blood Grouping and Crossmatching; D002648:Child; D002675:Child, Preschool; D017707:Erythrocyte Transfusion / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007518:Isoantibodies / Q000097:blood / Q000276:immunology; D008297:Male
chemical_list: D001789:Blood Group Antigens; D007518:Isoantibodies
keywords: alloimmunization; extended red cell typing; red cell transfusion; sickle cell anemia