The ability to modulate granulocyte-macrophage colony-forming unit (CFU- GM) Ia-antigen expression and response to growth inhibition in vitro was investigated in normals and patients with chronic myeloid leukemia (CML). The hyporesponsiveness of CML CFU-GM to inhibition by prostaglandin E and acidic isoferritins in vitro and their associated diminished capacity for Ia-antigen expression could be reversed following suspension culture of bone marrow cells in the presence of prostaglandin E prior to soft agar culture. Suspension preculture with prostaglandin E for 24 hr resulted in the detection of a population of CFU-GM that were equivalent to normal CFU-GM in both response to inhibition by prostaglandin E and acid isoferritins and in their pattern of Ia-antigen expression. Cytogenetic analysis of the progeny of CFU-GM proliferating in cultures established from marrow cells, cultured directly upon isolation or following suspension culture in the absence or presence of prostaglandin E for 24 hr, indicated that the responding cell population belonged to the Ph1-positive leukemic clone. Antigen detection on these CFU-GM resulted both from Ia-antigen reexpression and the induction of noncycling cells into S-phase with coincident expression of Ia-antigens. These studies provide further evidence for a direct regulatory association between Ia-antigen and control of granulocyte-macrophage progenitor cell proliferation, offer a possible explanation for the disordered regulatory responses observed in patients with CML, and indicate that abnormal growth phenotypes can be modulated, at least in vitro.

This content is only available as a PDF.
Copyright © 1983 by The American Society of Hematology
1983
Sign in via your Institution