Variable differentiation of human acute myeloid leukaemia during colony formation in vitro: a membrane marker analysis with monoclonal antibodies

Abstract

The capacities of human acute myeloid leukaemia (AML) cells for differentiation were evaluated by the degree of maturation of cells following in vitro colony formation. For this purpose highly purified blast cells were seeded into culture. Exogenous differentiation inducers, other than the colony stimulating materials, were not added to the cultures. Phenotypes of the colony cells were determined by use of monoclonal antibodies directed against a number of maturation antigens. In all 10 cases marked changes in the surface phenotypes of the cells post culture were seen. Differentiation was incomplete and quite variable as compared with normal myeloid colonies. Following colony formation myeloid maturation antigens became apparent on the cells of the one patient with morphologically undifferentiated leukaemia. The residual differentiation capacities among individual cases of human AML, as revealed in vitro, are diverse and do not parallel the morphological maturation features of the blasts prior to culture according to the FAB nomenclature. This approach may be utilized to improve the classification of human AML and to disclose the lineage relationship of certain cytologically unclassifiable leukaemias.