Kinetics of megakaryocyte progenitor cells in idiopathic thrombocytopenic purpura.

The number and proliferative state of megakaryocyte progenitor cells (CFU-Meg) were compared between 13 patients with idiopathic thrombocytopenic purpura (ITP) and hematologically normal controls. The mean frequency of CFU-Meg assayed by the plasma clot method was 27.8 +/- 12.2 (+/- SD)/2 x 10(5) bone marrow light-density cells for the ITP patients, which did not differ significantly from the control value of 31.9 +/- 16.1. The percentage of CFU-Meg in DNA synthesis estimated by the 3H-thymidine suicide technique was 41.3% +/- 9.2% in ITP, which was significantly greater than the control value of 27.1% +/- 7.4% (P less than 0.01). The megakaryocyte counts for histological sections prepared from bone marrow aspirates from the ITP patients and controls were 34.5 +/- 8.5/mm2 and 11.2 +/- 5.8/mm2, respectively, with the difference being highly significant (P less than 0.001). These results suggest that increased cycling activity in a quantitatively unchanged CFU-Meg pool may lead to increased megakaryocytes in the bone marrow of ITP patients.