The generation of dendritic-like cells with increased allostimulatory function from acute myeloid leukemia cells of various FAB subclasses.

To increase the immunogenicity of leukemic cells, attempts were made to generate dendritic-like antigen presenting cells (DC) from AML blasts from 14 patients with AML FAB classifications M0-M5. Leukemic cells were cultured in the presence or absence of various cytokines including GM-CSF, SCF, TNF-alpha, IL-4, and gamma-interferon. After various intervals recovery of viable cells was measured and expression of CD80, CD86, CD40, CD54, CD58, and CD11a was analyzed by flow cytometry. Functionally, DC derived from six AML samples were tested in a mixed lymphocyte response (MLR) using HLA-DR mismatched donor T cells as responder cells. Proliferation (5/14) or increased survival (7/14) of AML cells was observed in the presence of GM-CSF, SCF, and TNF-alpha. Only in the AML M2, M3, and M4 FAB subtypes proliferation was found. GM-CSF, SCF, and TNF-alpha induced morphologic changes typical for DC and increased the expression of costimulatory and adhesion molecules. No significant effect of IL-4 or gamma-interferon was observed. The day of maximal expression of these molecules varied. In cases with minor upregulation of CD80 or CD86, no further stimulation using CD40-L activation was observed. In the three cases tested, the DC-like cells retained the chromosomal abnormalities present in the original AML cells. In five out of six cases tested an increase in allostimulatory capacity was found at the day of maximal expression of costimulatory and adhesion molecules. In two patients a decrease in stimulatory capacity was found at day 7 compared with day 2 correlating with a decreased expression of these molecules. In conclusion, AML cells can be induced to increase their stimulatory capacity by upregulating costimulatory and adhesion molecules.