MEGAKARYOPOIESIS IN PATIENTS WITH CYCLIC THROMBOCYTOPENIA

Megakaryopoiesis was examined in 10 patients (eight females and two ma les) with cyclic thrombocytopenia (CT) to investigate the underlying p athogenesis. Numbers of CFU-Meg and megakaryocytes and the mean cytopl asmic area (mean area) of megakaryocytes at the peak, nadir, ascent mi d phase, and descent; mid phase of the platelet cycle were determined. The patients were classified as female cases group I(cases 1-4; previ ously diagnosed as ITP and CT occurred during remission), female cases group II (cases 58; persistent CT from initial diagnosis), and male C T (cases 9 and 10). In three of the four female cases in group I, numb ers of CFU-Meg and megakaryocytes were normal or increased persistentl y during the platelet cycle, whereas the mean area fluctuated in synch rony with the platelet cycle, suggesting failure of cyclic production rather than platelet destruction, In the female cases in group II and one female case in group I, numbers of CFU-Meg and megakaryocytes were also normal or increased at four phases of the cycle, but the mean ar ea did not fluctuate, remaining large during the cycle, suggesting cyc lic destruction or platelet clearance. In contrast, in the male patien ts values for numbers of CFU-Meg, megakaryocytes and mean cytoplasmic area fluctuated during the platelet cycle, indicating that cyclic chan ges in megakaryopoiesis generated the platelet cycle. These findings i ndicate that the measurement of cytoplasmic area is useful for disting uishing cyclic platelet production from cyclic destruction or clearanc e in CT.