[Study on induction of dendritic cells from myeloid leukemia cell lines and their antitumor immune function]

Dendritic cell (DC) plays a key role in antitumor immune response. However, there is a deficiency of DC function in the majority of leukemia patients. It is a novel idea that expanding DC in vitro and enhancing their antitumor immune function and DC-based tumor vaccines may be used as an efficient immune therapy for leukemia. In the project, the condition to induce DC from myeloid leukemia cell lines and its anti-leukemia response were investigated. HL-60, K562 and THP-1 cells were cultured with various combinations of cytokines for inducing DC. The morphologic features were analyzed with optical and electron microscopy. The phenotype of DC was detected by FCM with CD1a, CD40, CD80, CD86, HLA-A, B, C and HLA-DR monoclonal antibodies. The ability of DC stimulating lymphocyte proliferation was observed by allo-mixed lymphocyte reaction using (3)H-TdR incorporation. Cytotoxicity assay was measured by (51)Cr-release method. The level of IL-12 and IFN-gamma in supernatant of DC culture was measured by ELISA. It was proved that the DCs derived from K562, HL-60 and THP-1 cells showed a typical morphology of dendritic cell. The induced cells expressed the surface differentiation antigens of DC. A high expression of phenotypes was found in HL-60-DC and THP-1-DC stimulated by GM-CSF + IL-4 + TNF-gamma and K562-DC with GM-CSF + IL-4 + IL-12. The DCs from the 3 leukemia cell lines stimulated allo-MLR and CTL reaction strongly. Different contents of IL-12 were detected in the supernatants of DC culture and IFN-gamma in the coculture of DC and blood mononuclear cells. It is concluded that the myeloid leukemia cells are able to be induced DCs by cytokines in vitro. The different leukemia cells need different cytokines and cultural conditions. DCs derived from leukemia cells express phenotype of antigen-presenting cells. They have the ability of stimulating T lymphocyte proliferation and inducing CTL reaction to clear leukemia cells, and the DCs secrete IL-12 and increase secretion of IFN-gamma by T cells.