In vitro colony formation in bone marrow and spleen cell suspensions from rats with an acute myelogenous leukemia.

Abstract

Abstract Increases in the numbers of in vitro colony-forming cells (CFC) in the bone marrow were observed during the course of an acute myelogenous leukemia in the rat. CFC, not present in normal spleen suspensions, were evident in leukemic spleens. Colonies observed in cell suspensions harvested from rats in the advanced stages of leukemia were small, compact, and numerous; they appeared as tight clusters of cells. As the numbers of leukemic cells in the suspension increased, they tended to grow out as broad sheets encroaching upon colony formation. Leukemic cells in themselves did not form clusters or colonies. Titers of serum colony-stimulating factor (CSF) were increased in the early stages of the disease, however, serum collected from later stages inhibited colony growth. Media conditioned with leukemic cells inhibited in vitro colonies. Colony formation is discussed in relation to myelopoiesis during the leukemic state.