Megakaryocyte polyploidy and maturation in chronic granulocytic leukemia

To understand abnormal platelet production in chronic granulocytic leukemia, polyploidization and maturation of megakaryocytes in 10 patients were studied using a technique which allows sequential immunofluorescence identification by a monoclonal platelet antibody (C17), cytophotometric determination of the relative DNA content and cytological characterization of megakaryocytes in panoptically stained smears. Compared to normal conditions the proportion of diploid promegakaryocytes was not increased, suggesting an undisturbed influx of progenitor cells into the megakaryocytic cell compartment. Small tetraploid (4c) megakaryocytes undergo maturation without further polyploidization, the so-called microkaryocytes being mature rather than immature cells. Most of the megakaryocytes show rhythmical polyploidization only up to octoploid (8c) level, indicating the inability to produce high-polyploidy cells.