Granulopoietic differentiation in AML blasts in culture.

A newly described monoclonal antibody detected an antigen (My-1) that is expressed on the cell surface during normal granulopoietic differentiation. The kinetics of expression of My-1 and NASD chloracetate esterase were studied during the formation in culture of blast colonies and normal granulopoietic colonies. My-1-positive cells increased during blast colony formation in 6 of 9 experiments, while NASD esterase-positive cells decreased. In contrast, in normal granulopoiesis in culture both markers increased coherently. We suggest that components of granulopoietic differentiation programs are expressed abnormally during blast colony formation in culture.