title: HPA antibodies in Algerian multitransfused patients: Prevalence and involvement in platelet refractoriness.
abstract: BACKGROUND
  Patients receiving cellular blood components may form HLA or HPA antibodies. The frequency and the specificity of HPA antibodies after a series of blood transfusions have never been reported in the Algerian population which is ethnically diverse and runs a higher risk of platelet alloimmunization due to high b allelic frequencies observed for the HPA systems.
  
  
  METHODS
  117 polytransfused patients were included in this study; the detection of HPA antibodies was performed by the Monoclonal Antibody-specific Immobilization of Platelet Antigens method (MAIPA). Post-transfusion platelet effectiveness was evaluated by the calculation of corrected count increment (CCI).
  
  
  RESULTS
  The antibodies against platelets were detected in 10.26% of the patients. In this study, the platelet systems concerned by the alloimmunizations were specifically HPA-1, -3 and -5 with particular predominance of HPA-1. Twenty two patients were refractory to platelet transfusion, as assessed by a CCI; in which 64% have factors associated with increased platelet consumption. Platelet Immunization was found in 14% of platelet refractoriness (PTR) cases. 03 Anti-platelet antibodies were directed against GPIb-IX (n = 1), anti-HPA-1b (n = 1) and anti HPA-5b (n = 1) associated with anti-HLA antibodies in two cases.
  
  
  CONCLUSIONS
  HLA and HPA alloimmunization is common among chronically transfused patients. PTR detection, identification of the underlying causes, and selection of the appropriate product for transfusion are fundamental to reduce the risk of major bleedings.
authors.affiliation: Service of Blood Transfusion and Hemobiology, University Hospital Center of Annaba, Annaba, Algeria; Faculty of Medicine, University Badji Mokhtar of Annaba, Annaba, Algeria. Electronic address: hacenebrouk@yahoo.fr.
authors.forename: Hacene
authors.initials: H
authors.lastname: Brouk
authors.affiliation: Platelet Immunology Unit, Institut National de Transfusion Sanguine INTS, Paris, France.
authors.forename: Gérald
authors.initials: G
authors.lastname: Bertrand
authors.affiliation: Service of Blood Transfusion and Hemobiology, University Hospital Center of Annaba, Annaba, Algeria; Faculty of Medicine, University Badji Mokhtar of Annaba, Annaba, Algeria.
authors.forename: Selma
authors.initials: S
authors.lastname: Zitouni
authors.affiliation: Faculty of Medicine, University Badji Mokhtar of Annaba, Annaba, Algeria; Service of Hematology, University Hospital Center of Annaba, Annaba, Algeria.
authors.forename: Amel
authors.initials: A
authors.lastname: Djenouni
authors.affiliation: Platelet Immunology Unit, Institut National de Transfusion Sanguine INTS, Paris, France.
authors.forename: Corinne
authors.initials: C
authors.lastname: Martageix
authors.affiliation: Faculty of Medicine, University Badji Mokhtar of Annaba, Annaba, Algeria; Service of Hematology, University Hospital Center of Annaba, Annaba, Algeria.
authors.forename: Fatiha
authors.initials: F
authors.lastname: Griffi
authors.affiliation: Platelet Immunology Unit, Institut National de Transfusion Sanguine INTS, Paris, France.
authors.forename: Cecile
authors.initials: C
authors.lastname: Kaplan
authors.affiliation: Service of Blood Transfusion and Hemobiology, University Hospital Center of Annaba, Annaba, Algeria; Faculty of Medicine, University Badji Mokhtar of Annaba, Annaba, Algeria.
authors.forename: Hanifa
authors.initials: H
authors.lastname: Ouelaa
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000462:Algeria; D000483:Alleles; D000755:Anemia, Sickle Cell / Q000097:blood / Q000276:immunology* / Q000628:therapy; D000911:Antibodies, Monoclonal / Q000737:chemistry; D016824:Antigens, Human Platelet / Q000276:immunology*; D016913:Blood Component Transfusion / Q000009:adverse effects*; D001792:Blood Platelets / Q000276:immunology; D001803:Blood Transfusion; D002648:Child; D005006:Ethnicity; D005260:Female; D005838:Genotype; D006680:HLA Antigens / Q000276:immunology*; D006470:Hemorrhage; D006801:Humans; D007518:Isoantibodies / Q000097:blood; D007938:Leukemia / Q000097:blood / Q000276:immunology* / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D017713:Platelet Transfusion; D015995:Prevalence; D012680:Sensitivity and Specificity; D055815:Young Adult; D017086:beta-Thalassemia / Q000097:blood / Q000276:immunology* / Q000628:therapy
chemical_list: D000911:Antibodies, Monoclonal; D016824:Antigens, Human Platelet; D006680:HLA Antigens; D007518:Isoantibodies
keywords: HPA; MAIPA; PTR; Platelet alloimmunization; Polytransfused patients