title: Posttransfusion purpura secondary to an alloantibody reactive with HPA-5a (Br(b)).
abstract: BACKGROUND
  Posttransfusion purpura (PTP) is characterized by severe thrombocytopenia following blood transfusion that results from alloimmunization to platelet-specific alloantigens. Most cases involve antibodies against HPA-1a in homozygous HPA-1b persons.
  
  
  METHODS
  A patient developed PTP after cardiopulmonary bypass associated with a platelet-specific antibody with strong reactivity against HPA-5a (Br(b)). Geno-typing confirmed that the patient was homozygous for HPA-5b.
  
  
  CONCLUSIONS
  This is the first well-documented occurrence of PTP associated with isolated allosensitization to HPA-5a or Br(b). The case highlights the importance of maintaining a high level of suspicion for PTP in the appropriate clinical setting, even in an atypical patient.
authors.affiliation: Rheumatology and Immunology Unit and the Vascular Medicine Unit, Department of Medicine, University of Rochester School of Medicine and Dentistry, NY, USA.
authors.forename: J H
authors.initials: JH
authors.lastname: Anolik
authors.forename: N
authors.initials: N
authors.lastname: Blumberg
authors.forename: J
authors.initials: J
authors.lastname: Snider
authors.forename: C W
authors.initials: CW
authors.lastname: Francis
mesh_terms: D000368:Aged; D006801:Humans; D007518:Isoantibodies / Q000276:immunology*; D008297:Male; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000276:immunology*; D011693:Purpura / Q000209:etiology*; D065227:Transfusion Reaction
chemical_list: D007518:Isoantibodies; D019039:Platelet Glycoprotein GPIIb-IIIa Complex