Human megakaryocytes. III. Characterization in myeloproliferative disorders
EM Rabellino, RB Levene, RL Nachman and LL Leung
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-micron 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 two patients with polycythemia
vera, representing between 60 and 1,840 cells/10(4) cells (less than 1.050
g Percoll/cu cm). No atypical megakaryocytes were found in (a) 20 normal
controls, (b) two patients with essential thrombocythemia, (c) a patient
with thrombocytosis secondary to acute bleeding, and (d) in two patients
with CML. Atypical megakaryocytes appear to represent a single-cell
population, as demonstrated by a series of double immunofluorescence assays
using combinations of five 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 two different
immunofluorescence systems have demonstrated that phenotypic similarities
existed between atypical megakaryocytes and myeloproliferative platelet
proteins and differentiation markers on megakaryocytes are useful in
elucidating the pathophysiologic alterations occurring in the
megakaryocytic compartment in patients with myeloproliferative disorders.
Volume 63,
Issue 3,
pp. 615-622,
03/01/1984
Copyright © 1984 by The American Society of Hematology
