HUMAN MEGAKARYOCYTES .3. CHARACTERIZATION IN MYELOPROLIFERATIVE DISORDERS

  • 1 January 1984
    • journal article
    • research article
    • Vol. 63  (3) , 615-622
Abstract
Abnormal proliferation of the megakaryocytic line was observed in the marrow tissue from patients with myeloproliferative disorders. Megakaryocytes were identified by immunofluorescence using distinct platelet protein markers. Plasma factor VIII antigen (factor VIII:AGN) and platelet glycoproteins IIb and IIIa were detected in normal mature and early megakaryocytes, as well as in a morphologically heterogeneous population of low density marrow cells regarded as atypical megakaryocytes. Atypical megakaryocytes were defined as oval/round 14-35 .mu.m diameter blast-like mononuclear/multinucleated cells bearing platelet protein markers with distinct morphological features, including cytoplasmic vacuolation, variable nuclear/cytoplasmic ratios, and variable cytoplasmic granulation. Atypical megakaryocytes were observed in most chronic myelogenous leukemia (CML) patients and in 2 patients with polycythemia vera, representing between 60 and 1840 cells/104 cells (< 1.05 g Percoll/cm3). No atypical megakaryocytes were found in 20 normal controls, 2 patients with essential thrombocythemia, a patient with thrombocytosis secondary to acute bleeding and in 2 patients with CML. Atypical megakaryocytes appear to represent a single-cell population, as demonstrated by a series of double immunofluorescence assays using combinations of 5 different antiplatelet protein sera. There was a statistically significant correlation between the frequency of atypical megakaryocytes and the presence of immature forms of myeloid cells in blood. Analyses of Fc IgG receptors conducted with 2 different immunofluorescence systems have demonstrated that phenotypic similarities existed between atypical megakaryocytes and myeloproliferative platelets. Analyses of platelet proteins and differentiation markers on megakaryocytes are useful in elucidating the pathophysiologic alterations occurring in the megakaryocytic compartment in patients with myeloproliferative disorders.