title: Platelet activation and platelet-leukocyte interaction in β-thalassemia/hemoglobin E patients with marked nucleated erythrocytosis.
abstract: Patients with thalassemia, an inherited hemolytic anemia, have increased risk of hypercoagulable complications. A whole blood flow cytometric (FCM) method has been used for studies of platelet activation and platelet-leukocyte aggregation in these patients. However, this FCM method presents technical difficulties because of the high proportion of immature red blood cells (RBCs) in these patients. A protocol for the simultaneous measurement of platelet activation and their aggregation with leukocyte populations in whole blood using four-color FCM which excluded immature RBC was devised, and evaluated for the evaluation of platelet function in patients with β-thalassemia/hemoglobin E (HbE). Whole blood from these patients and from healthy volunteers was stained for platelet activation and platelet-leukocyte aggregates using anti-CD42a, anti-CD62P, anti-CD45 and glycophorin A (GPA) conjugated with different fluorochromes. Our FCM method is simple, effective and based on the assumption that GPA is present on all immature RBCs, but is not expressed on CD45⁺ leukocytes. Results from the studies showed that blood samples from these patients contained a high frequency of circulating activated platelets (CD42a⁺/CD62P⁺) when compared to samples from healthy individuals. The percentage of platelet-neutrophil, platelet-monocyte-but not platelet-lymphocyte-aggregates were also elevated in both thalassemia genotypes with marked increase in patients who had undergone splenectomy. These findings suggest that platelets adhere to neutrophils and monocytes are activated which support the clinical observation that splenectomized thalassemia patients have an increased risk of arterial or venous thrombotic manifestations.
authors: Center of Excellence for Flow Cytometry, Office for Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
authors: Rassamon
authors: R
authors: Keawvichit
authors: Ladawan
authors: L
authors: Khowawisetsut
authors: Porntip
authors: P
authors: Chaichompoo
authors: Korakot
authors: K
authors: Polsrila
authors: Suchana
authors: S
authors: Sukklad
authors: Kasama
authors: K
authors: Sukapirom
authors: Archrob
authors: A
authors: Khuhapinant
authors: Suthat
authors: S
authors: Fucharoen
authors: Kovit
authors: K
authors: Pattanapanyasat
mesh_terms: D001792:Blood Platelets / Q000378:metabolism / Q000473:pathology*; D002449:Cell Aggregation; D004900:Erythroblasts / Q000378:metabolism / Q000473:pathology; D005434:Flow Cytometry / Q000379:methods; D006021:Glycophorins / Q000378:metabolism; D006446:Hemoglobin E / Q000032:analysis*; D006801:Humans; D007564:Japan; D017493:Leukocyte Common Antigens / Q000378:metabolism; D007962:Leukocytes / Q000378:metabolism / Q000473:pathology*; D009000:Monocytes / Q000378:metabolism / Q000473:pathology; D009504:Neutrophils / Q000378:metabolism / Q000473:pathology; D015539:Platelet Activation; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism; D011086:Polycythemia / Q000209:etiology*; D013156:Splenectomy / Q000009:adverse effects; D013927:Thrombosis / Q000209:etiology; D017086:beta-Thalassemia / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology / Q000601:surgery
chemical_list: C409972:GYPA protein, human; D006021:Glycophorins; D010980:Platelet Membrane Glycoproteins; D006446:Hemoglobin E; D017493:Leukocyte Common Antigens; C516769:PTPRC protein, human