Generation of dendritic cells from human chronic myelomonocytic leukemia cells in fetal calf serum-free medium.

It is generally believed that the immune system plays a role not only in the acquisition of malignant diseases but also in the rejection of microscopic as well as established tumor cells. Failure of the immune system to eliminate tumor cells may be, among other factors, due to an insufficient presentation of tumor antigens. Dendritic cells (DCs), as professional antigen-presenting cells, therefore, may be therapeutically used to initiate or enhance immune responses in patients with malignancies. In this study we demonstrate that peripheral blood cells of patients with chronic myelomonocytic leukemia (CMML) can be induced to acquire DC characteristics. Upon culture with granulocyte-macrophage colony-stimulating factor (GM-CSF) plus interleukin-4 (IL-4) plus tumor necrosis factor alpha (TNFalpha), CMML cells develop DC morphology and acquire the phenotypic characteristics of DCs. When a CD14+ cell population is used for DC generation, a homogeneous differentiation towards the DC lineage occurs similar to that, observed in normal peripheral blood monocytes. CMML-derived DCs are potent stimulators of the allogeneic mixed lymphocyte reaction (MLR) when compared with uncultivated cells. The demonstration of a deletion of the long arm of chromosome 7, del(7)(q22), in 86% of highly enriched CD1a+ cells by fluorescence in situ hybridization (FISH) indicates the leukemic origin of generated DCs. In addition, we present data that generation of CMML-derived DCs is also possible under fetal calf serum-free conditions for a potential clinical use. These DCs may be used as a cellular vaccine to induce anti-tumor immunity in patients with CMML.