Adherent cells in cultures of blast progenitors in acute myeloblastic leukemia

Blast cells from patients with acute myelogenous leukemia (AML) grow exponentially in suspension culture and form colonies in cultures "stiffened" with methylcellulose; under both culture conditions, cells are generated which have the ability to adhere to plastic or glass. These adherent cells lack the capacity to form colonies, to proliferate in liquid culture or to support growth. Adherent cells are generated in parallel with changes in the frequency of clonogenic cells and express surface markers of AML blasts but with a higher frequency of an antigen recognized by the monoclonal MO1, a late stage marker associated with the macrophage differentiation lineage. While the appearance of adherent cells provides further evidence that blast cells follow differentiation programs in culture, the generation of adherent cells does not indicate that normal differentiation is occurring; rather the data is consistent with the view that components of normal monocytic differentiation programs are assembled abnormally in the programs of some blast progenitors.