Establishment of a leukemic cell line MT-ALL with multilineage differentiation potential.

Multiple steps are involved in hematopoietic differentiation and maturation from multipotent progenitor cells to terminally differentiated cells of each lineage. The availability of recombinant growth factors and of various clonogenic precursor cell assays has provided useful information about hematopoietic precursors, notably of the myeloid lineage [13]. However, the direct evaluation of primitive human lymphohematopoietic progenitor cells has been hampered by their low frequency in normal donors and the difficulties involved in expanding them in in vitro culture [4, 5]. Therefore, little is known about the events and mechanisms that result in the irreversible commitment of multipotent uncommitted progenitors to a specific cell lineage. Leukemias have been traditionally used as a model for lymphohematopoietic development and have been studied extensively for the expression of differentia-