title: Nonfatal intravascular hemolysis in a pediatric patient after transfusion of a platelet unit with high-titer anti-A.
abstract: BACKGROUND
  In the pediatric population, hemolysis after out-of-group platelet (PLT) transfusion is a potentially fatal event that is thought to be underrecognized. Group A patients transfused with group O single-donor PLTs (SDPs) with "high-titer" anti-A are at greatest risk for hemolysis.
  
  
  METHODS
  A clinical and serologic evaluation of a pediatric patient with hemolysis of initially unknown etiology was conducted. Retrospective testing for anti-A titer of an admission sample and a transfused group O SDP was performed.
  
  
  RESULTS
  The group A patient (previously group O) was found to have a history of engrafted major ABO-mismatched hematopoietic peripheral blood progenitor cell transplant (HPBPCT). Immune-mediated intravascular hemolysis with a delayed presentation was determined. Testing identified passive anti-A in the patient's plasma and high-titer anti-A (IgG 4096, IgM 256) in the group O SDP unit.
  
  
  CONCLUSIONS
  Hemolysis after out-of-group SDP transfusion may be delayed in presentation and, thus, clinically unrecognized. When evaluating these cases, the limitations of routine type and screen for detection of passive anti-A must be considered. Group A individuals with a history of engrafted major ABO-mismatched HPBPCT potentially have increased susceptibility to hemolysis from group O SDP transfusion due to their lack of tissue and soluble A antigen.
authors.affiliation: Transfusion Medicine Program, Department of Pathology and Laboratory Medicine, Emory University School of Medicine, 1364 Clifton Road NE, Atlanta, GA 30322, USA.
authors.forename: Shealynn B
authors.initials: SB
authors.lastname: Harris
authors.forename: Cassandra D
authors.initials: CD
authors.lastname: Josephson
authors.forename: Christine B
authors.initials: CB
authors.lastname: Kost
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Hillyer
mesh_terms: D000017:ABO Blood-Group System / Q000276:immunology*; D001787:Blood Group Incompatibility / Q000150:complications*; D002648:Child; D005260:Female; D006461:Hemolysis; D006801:Humans; D017713:Platelet Transfusion / Q000009:adverse effects*
chemical_list: D000017:ABO Blood-Group System