title: Platelet hyperactivity in thalassemia patients with elevated tricuspid regurgitant velocity and the association with hemolysis.
abstract: BACKGROUND
  Pulmonary arterial hypertension is a life-threatening complication in thalassemia characterized by elevated pulmonary arterial pressure. Increased platelet activation is associated with this complication; however, its role remains unclear.
  
  
  METHODS
  Platelet activation in splenectomized β-thalassemia/hemoglobin E (Hb E) patients was measured using flow cytometric determination of P-selectin and activated glycoprotein (aGP) IIb/IIIa expression, and platelet-leukocyte aggregates (platelet-neutrophil, platelet-monocyte and platelet-lymphocyte aggregates). Tricuspid regurgitant velocity (TRV) was measured and used as an indicator of pulmonary arterial pressure. Plasma hemoglobin served as markers of hemolysis.
  
  
  RESULTS
  Fifteen of 27 patients had elevated TRV (>2.5m/s). Platelet expression of P-selectin and aGPIIb/IIIa, and platelet-leukocyte aggregates were higher in thalassemia patients with elevated TRV than healthy control. Platelet-neutrophil aggregates increased in thalassemia patients with elevated TRV compared to patients with normal TRV. The increase in P-selectin and aGPIIb/IIIa expression induced by adenosine diphosphate (ADP) was higher in patients with elevated TRV than those with normal TRV. Platelet P-selectin expression and platelet-neutrophil aggregates correlated positively with TRV. Plasma hemoglobin levels in patients with elevated TRV were higher than those of the control subjects, and correlated with TRV.
  
  
  CONCLUSIONS
  Thalassemia patients with elevated TRV have a further increase in platelet activation that correlates with hemolysis.
authors.affiliation: Department of Pharmacology, Faculty of Dentistry, Mahidol University, Bangkok, Thailand.
authors.forename: Sirada
authors.initials: S
authors.lastname: Srihirun
authors.affiliation: Department of Medicine, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: Navy
authors.initials: N
authors.lastname: Tanjararak
authors.affiliation: Department of Medicine, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: Suporn
authors.initials: S
authors.lastname: Chuncharunee
authors.affiliation: Department of Medicine, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: Piyamitr
authors.initials: P
authors.lastname: Sritara
authors.affiliation: Center of Excellence for Flow Cytometry, Office for Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: Rassamon
authors.initials: R
authors.lastname: Kaewvichit
authors.affiliation: Thalassemia Research Center, Institute of Science and Technology for Research and Development, Mahidol University, Nakhonpathom, Thailand.
authors.forename: Suthat
authors.initials: S
authors.lastname: Fucharoen
authors.affiliation: Center of Excellence for Flow Cytometry, Office for Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: Kovit
authors.initials: K
authors.lastname: Pattanapanyasat
authors.affiliation: Department of Pharmacology, Faculty of Science, Mahidol University, Thailand. Electronic address: nathawut.sib@mahidol.ac.th.
authors.forename: Nathawut
authors.initials: N
authors.lastname: Sibmooh
mesh_terms: D000328:Adult; D001792:Blood Platelets / Q000166:cytology*; D001794:Blood Pressure; D001803:Blood Transfusion; D016022:Case-Control Studies; D005434:Flow Cytometry; D006454:Hemoglobins / Q000378:metabolism; D006461:Hemolysis; D006801:Humans; D007962:Leukocytes / Q000166:cytology; D008875:Middle Aged; D009504:Neutrophils / Q000166:cytology; D019007:P-Selectin / Q000097:blood; D015539:Platelet Activation; D011651:Pulmonary Artery / Q000473:pathology; D014261:Tricuspid Valve / Q000473:pathology*; D014262:Tricuspid Valve Insufficiency; D017086:beta-Thalassemia / Q000097:blood*
chemical_list: D006454:Hemoglobins; D019007:P-Selectin
keywords: Hemolysis; Plasma hemoglobin; Platelet; Pulmonary arterial pressure; Thalassemia; Tricuspid regurgitant velocity