Sirada Srihirun1, Navy Tanjararak2, Suporn Chuncharunee2, Piyamitr Sritara2, Rassamon Kaewvichit3, Suthat Fucharoen4, Kovit Pattanapanyasat3, Nathawut Sibmooh5. 1. Department of Pharmacology, Faculty of Dentistry, Mahidol University, Bangkok, Thailand. 2. Department of Medicine, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand. 3. Center of Excellence for Flow Cytometry, Office for Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand. 4. Thalassemia Research Center, Institute of Science and Technology for Research and Development, Mahidol University, Nakhonpathom, Thailand. 5. Department of Pharmacology, Faculty of Science, Mahidol University, Thailand. Electronic address: nathawut.sib@mahidol.ac.th.
Abstract
INTRODUCTION: 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. CONCLUSION: Thalassemia patients with elevated TRV have a further increase in platelet activation that correlates with hemolysis.
INTRODUCTION: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 thalassemiapatients with elevated TRV than healthy control. Platelet-neutrophil aggregates increased in thalassemiapatients 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. CONCLUSION:Thalassemiapatients with elevated TRV have a further increase in platelet activation that correlates with hemolysis.