Early and late hemopoietic precursor cells in patients with chronic myeloproliferative diseases.

We evaluated the content of early and late cobblestone area-forming cells, immediate progeny of hemopoietic stem cells, and committed precursor cells in the bone marrow and peripheral blood of patients with chronic myeloproliferative diseases and healthy donors. In patients with essential thrombocythemia, the number of late cobblestone area-forming cells in the peripheral blood decreased, while other parameters did not differ from those in healthy donors. In patients with idiopathic myelofibrosis, we found a decreased number of late and early cobblestone area-forming cells in the bone marrow and late cobblestone area-forming cells in the peripheral blood, while the count of early cobblestone area-forming cells in the peripheral blood increased. In patients with chronic myeloid leukemia, the number of early cobblestone area-forming cells in the bone marrow decreased, but the count of late and early cobblestone area-forming cells in the peripheral blood increased. The number of endogenous committed precursor cells in the peripheral blood increased in all groups of patients with chronic myeloproliferative diseases and, particularly, in patients with idiopathic myelofibrosis and chronic myeloid leukemia. Functional characteristics of immediate descendants of hemopoietic stem cells probably reflect the level of damage and attest to the existence of various mechanisms underlying the defect of the hemopoietic stem cell during chronic myeloproliferative diseases.