title: Direct evidence for normalization of platelet function resulting from platelet count reduction in essential thrombocythemia.
abstract: Essential thrombocythemia is characterized by persistent elevation and functional disturbances of platelets. Both the platelet function analyzer-100 (PFA-100) collagen-epinephrine (CEPI) cartridge and aggregometry with epinephrine are considered sensitive and valid methods in detecting abnormal platelet function in essential thrombocythemia. We attempted to confirm that restoration of abnormal platelet function results from platelet count reduction in essential thrombocythemia, by using these two methods. Thirty-nine essential thrombocythemia patients were divided into two groups on the basis of their platelet count. Group A participants (n = 20) exhibited platelet counts greater than 500 × 10/l, whereas group B participants (n = 19) had platelet counts below this limit. Hematological parameters, plasma von Willebrand factor (vWF) antigen and activity levels were assessed. Platelet function was analyzed by the PFA-100 and light transmission aggregometry with epinephrine, collagen, and ADP. The point mutation JAK2 V617F was identified and its effect on platelet function tests was also investigated. By using logistic regression analysis, white blood cell count, vWF activity level, and the measurements of aggregation in response to epinephrine were significantly different between the two groups. Epinephrine-induced aggregation retained the statistical significance in the multivariable procedure (P : 0.002). PFA-100 CEPI closure times were lower - but not statistically significant - in group B. Neither the JAK2 V617F positivity nor different cytoreductive treatments had any influence on ex-vivo platelet function tests. Our findings demonstrate normalization of platelet function resulting from platelet count reduction in essential thrombocythemia and reinforce the concept of lowering platelet counts in these patients.
authors.affiliation: Laboratory of Haematology and Blood Bank Unit, Attikon General Hospital, School of Medicine, University of Athens, 1 Rimini Str., Athens, Greece. atsantes@yahoo.com
authors.forename: Argirios E
authors.initials: AE
authors.lastname: Tsantes
authors.forename: Georgios K
authors.initials: GK
authors.lastname: Nikolopoulos
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Tsirigotis
authors.forename: Katerina
authors.initials: K
authors.lastname: Zoi
authors.forename: Athanasios
authors.initials: A
authors.lastname: Zomas
authors.forename: Violetta
authors.initials: V
authors.lastname: Kapsimali
authors.forename: Petros
authors.initials: P
authors.lastname: Kopterides
authors.forename: Spyros
authors.initials: S
authors.lastname: Chondropoulos
authors.forename: John
authors.initials: J
authors.lastname: Dervenoulas
authors.forename: Georgios
authors.initials: G
authors.lastname: Mantzios
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000328:Adult; D001241:Aspirin / Q000494:pharmacology; D001792:Blood Platelets / Q000166:cytology* / Q000187:drug effects; D003094:Collagen / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology; D005260:Female; D006115:Greece; D006801:Humans; D006918:Hydroxyurea / Q000008:administration & dosage* / Q000627:therapeutic use; D016898:Interferon-alpha / Q000008:administration & dosage* / Q000627:therapeutic use; D053614:Janus Kinase 2 / Q000737:chemistry / Q000235:genetics; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects; D010976:Platelet Count; D010979:Platelet Function Tests / Q000379:methods*; D017354:Point Mutation; D012044:Regression Analysis; D013920:Thrombocythemia, Essential / Q000175:diagnosis / Q000188:drug therapy* / Q000473:pathology; D014841:von Willebrand Factor / Q000032:analysis
chemical_list: D016898:Interferon-alpha; D014841:von Willebrand Factor; D000244:Adenosine Diphosphate; D003094:Collagen; C507924:JAK2 protein, human; D053614:Janus Kinase 2; D001241:Aspirin; D006918:Hydroxyurea; D004837:Epinephrine