PROLIFERATIVE STATE OF BLAST CELL PROGENITORS IN ACUTE MYELOBLASTIC-LEUKEMIA (AML)

Abstract

Peripheral blood from patients with AML contains cells capable of giving rise to colonies in culture when stimulated by media conditioned by leukocytes (LCM) in the presence of phytohemagglutinin (PHA). Two types of colonies were recognized with high frequency. The first grew in the presence of low concentrations of PHA LCM, had a blast-like morphology and were numerically correlated with morphologically identified blast cells. The second required high PHA LCM concentrations or PHA alone with or without 2-mercaptoethanol, and consisted of cells capable of forming rosettes with sheep erythrocytes and resembled T [thymus-derived] lymphocyte colonies from normal blood. Precursors of blast cell colonies from 15 leukemic patients were tested for cycle state, using the 3H-thymidine or hydroxyurea techniques. All had a high proportion of cells in the S phase of the cycle. T lymphocyte precursors from 3 normal individuals were quiescent. The data are consistent with the maintenance of the leukemic blast cell populations by the proliferative activity of a small subpopulation of blasts.