fibrinopeptide-a and Primary-Myelofibrosis

Platelet function and the clinical course of the disease were prospectively investigated in 29 patients with myeloproliferative disorders. Serial determinations (median: 5 investigations per patient within 17 months) of platelet aggregation, plasma and intraplatelet concentrations of beta-thromboglobulin (beta TG) and platelet factor 4 (PF4), and of fibrinopeptide A (FPA) plasma levels were carried out. In the chronic phase of polycythaemia vera, patients with thrombohaemorrhagic complications during the study period had higher platelet count, more severe platelet aggregation defects, and increased plasma levels of beta TG and FPA compared to patients without complications. However, thrombohaemorrhagic complications were not predicted by changes in these parameters in the individual patient during the chronic disease phase. When patients with chronic myelogenous leukaemia entered blast crisis, bleeding complications were related to thrombocytopenia, impaired platelet function and low intraplatelet concentrations of beta TG and PF4. Cytoreduction by chemotherapy in the chronic phase of CML did not alter beta TG and PF4 plasma levels, whereas treatment of polycythaemia rubra vera by venesection favourably influenced platelet alpha-granule secretion and increased intraplatelet concentrations of beta TG and PF4.

Topics: Adult; Aged; beta-Thromboglobulin; Blood Platelets; Female; Fibrinopeptide A; Hemorrhage; Hemostasis; Humans; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Leukocyte Count; Male; Middle Aged; Myeloproliferative Disorders; Platelet Aggregation; Platelet Count; Platelet Factor 4; Polycythemia Vera; Primary Myelofibrosis; Prospective Studies; Thrombocythemia, Essential; Thrombosis

The in vivo platelet release reaction in 22 patients with myeloproliferative disorders has been studied by measuring plasma concentrations of the platelet release product beta-thromboglobulin (beta TG). Mean beta TG and mean beta TG: whole blood platelet count ratio were significantly raised in the patient group taken as a whole compared to an age matched control group. No significant increases were observed in the plasma concentrations of thrombin and plasmin sensitive fibrinogen fragments fibrinopeptide A (FpA) and B beta 1-42. The patients were divided into those who had normal, increased or decreased responses to in vitro ADP-induced platelet aggregation. Mean beta TG and the mean beta TG: whole blood platelet count ratio were higher in the increased and decreased responders to ADP than in the normal aggregation group, but the differences in means were not statistically significant. Aspirin given to six patients at a dose sufficient to eliminate the secondary phase of ADP-induced platelet aggregation reduced mean beta TG and the mean beta TG: whole blood platelet count ratio but did not alter mean FpA and B beta 1-42. It is concluded that the enhanced platelet release reaction seen in myeloproliferative disorders is independent of plasma protease activity that arises when coagulation and fibrinolytic systems are activated.

Topics: Aged; Aspirin; beta-Thromboglobulin; Blood Platelets; Fibrinopeptide A; Fibrinopeptide B; Humans; Middle Aged; Myeloproliferative Disorders; Platelet Aggregation; Platelet Count; Polycythemia Vera; Primary Myelofibrosis