Late Myelosuppressive Action of Programmed Chemotherapy in Acute Lymphoblastic Leukemia in Children.

The capability of peripheral blood leukocytes and bone marrow cells to spontaneous apoptosis was studied in 36 children with ALL remission at various periods after polychemotherapy withdrawal. The enhancement of apoptotic activity has been revealed to be the universal mechanism of delayed effect of antileukemic chemotherapy for all the compartments of hemopoiesis, including granulocyte/macrophage precursors. The expression of this phenomenon is decreasing with the time period elapsed after treatment withdrawal. However, approximation analysis shows that the recovery of normal values of blood cell apoptosis occurs not earlier than 8 years after therapy withdrawal. Therein, in should be noted that the numbers of leukocytes don't differ from normal values at all the periods of observation. The growth of proliferative potential for precursor cells and the increased proportion of proliferating granulocyte pool of bone marrow are shown to be the probable mechanisms contributing to compensation of enhanced ability of blood cells to apoptosis.