OBJECTIVETo study the impact of an agonist anti-CD(40) monoclonal antibody 5C11 on the induction and biological characteristics of leukemic dendritic cells.

METHODSCombinations of 5C11 and different cytokines were used to induce differentiation of leukemic blasts into dendritic cells. Morphology was observed by light microscopy. Surface antigens of the induced cells were analyzed by fluorescence-activated cell sorting (FACS), the yields of dendritic cell by cell counting, the levels of IL-6 and IL-12 by ELISA, T cell proliferating activity by allo-mixed lymphocyte reaction (MLR) in vitro. Allogeneic T cells were stimulated with leukemic dendritic cells and T-cell cytotoxicity was measured by MTT assay.

RESULTSWhen cultured with combinations of 5C11 and different cytokines, the leukemic cells isolated from the patients could differentiate into dendritic cells. The morphology showed typical features of dendritic cells, which expressed high levels of CD(40), CD(80) and CD(86). In comparison with the original leukemia cells, the leukemic dendritic cells secreted less IL-6 but more IL-12 (P < 0.05). The leukemic dendritic cells were potent to stimulate the proliferation of allogeneic T cells, and the latter was able to lyse the original leukemia cells.

CONCLUSIONLeukemic blasts could be induced to differentiate into functional dendritic cells. It may be of great value in the adoptive immunologic therapy of leukemia.