Calcium ionophore (CI) is used to generate dendritic cells (DCs) from progenitor cells, monocytes, or leukemic cells. The aim of this study was to determine the optimal dose of CI and the appropriate length of cell culture required for acute myeloid leukemia (AML) cells and to evaluate the limitations associated with CI.

To generate leukemic DCs, leukemic cells (4×10⁶ cells) from six AML patients were cultured with various concentrations of CI and/or IL-4 for 1, 2 or 3 days.

Potent leukemic DCs were successfully generated from all AML patients, with an average number of 1.2×10⁶ cells produced in the presence of CI (270 ng/ml) for 2 days. Several surface molecules were clearly upregulated in AML cells supplemented with CI and IL-4, but not CD11c. Leukemic DCs cultured with CI had a higher allogeneic T cell stimulatory capacity than untreated AML cells, but the addition of IL-4 did not augment the MLR activity of these cells. AML cells cultured with CI in the presence or absence of IL-4 showed increased levels of apoptosis in comparison to primary cultures of AML cells.

Although CI appears to be advantageous in terms of time and cost effectiveness, the results of the present study suggest that the marked induction of apoptosis by CI limits its application to the generation of DCs from AML cells.