Human Leukemic Cells: In vitro Growth of Colonies Containing the Philadelphia (Ph 1 ) Chromosome

Abstract
Human leukemic cells with a marker (Philadelphia; Ph1) chromosome gave rise to granulocytic and mononuclear cell colonies when grown in vitro. All metaphases from a single colony were either Ph1 positive or Ph1 negative. No colonies contained a mixed cell population. This suggests that leukemic and normal cells exist simultaneously and that in vitro colonies are clonal in origin.