Use of the tritiated thymidine-labelling index of the myeloblast-promyelocyte pool for the identification of the leukemic population in oligoblastic leukemia.

The bone marrow myeloblast-promyelocyte-labelling index of 32 patients with oligoblastic leukemia was studied at diagnosis and during the course of the disease. A low value (less than 0.17) or a decrease in the labelling index is suggestive of a poor prognosis with development into acute myeloblastic leukemia. Leukemic myeloblasts are characterized by their inability to differentiate and their low labelling index. The low labelling index or the decrease in this labelling index are, thus, an indication of an increase in the leukemic population.