Myeloid differentiation antigens identify leukemic cell subpopulations with different cell cycle characteristics.

In order to assess the proliferative capacity of leukemic subpopulations and to know whether it can be related to the stage of maturation, the expression of two surface antigens identifying distinct steps of leukocyte differentiation (CD15 and CD34) was studied by flow cytometry in correlation with DNA content in 16 cases of acute myeloid leukemia (AML). The surface markers were studied by indirect immunofluorescence, using the monoclonal antibodies VIMD5 (anti-CD15) and MY10 (anti-CD34). The percentage of cells stained by each antibody and the intensity of staining were heterogeneous. Double-staining showed that a small percentage of cells coexpressed both antigens. A correlation was found between the percentage of cells stained by MY10 and the percentage of cells in S + G2 + M in the whole population (p less than 0.05). The percentage of cells in S + G2 + M was significantly higher in MY10-positive than in MY10-negative cells (p less than 0.005), and also higher in VIMD5-positive than in VIMD5-negative cells (p less than 0.005). In the 14 cases expressing both antigens, the percentage of cells in S + G2 + M was higher in VIMD5-positive than in MY10-positive cells (p less than 0.05), whereas there was no difference between VIMD5-negative and MY10-negative cells. It is concluded that the phenotype heterogeneity observed in leukemic cell populations is associated with differences in proliferative capacities. The subset of leukemic cells with the more mature phenotype (CD15-positive) has the highest proliferative activity.