Abstract: Objective Dentritic cells (DCs) from malignant pleural effusions of patients with lung cancer were isolated and induced.Effect of DCs on proliferation and cytotoxicity of tumor infiltration lymphocytes (TILs) from origin malignant pleural effusions was studied. Methods Pleural effusion mononuclear cells were obtained from 16 patients with lung cancer.Cells were separated by density gradient and magnetic cell sorting system.DCs were induced by interleukin-4 (IL-4), tumor necrosis factor-α(TNF-α), and granulocyte-macrophage colony stimulating.DCs were observed by optical microscope, electronic microscope and flow cytometry respectively.TILs from origin malignant pleural effusions were induced by IL-2 and phytohemagglutinin.The cancer cells were separated with HEA-125 magnetic cell sorting system.The ability of stimulating the proliferation of TILs was detected with 3H-thymidine.The anti-tumor effect of TILs was measured with MTT method. Results The mature DCs from malignant pleural effusions of patients with lung cancer could be induced.The typical morphology in DCs was observed with optical and electronic microscopes.DCs expressed high-level surface phenotypes, including HLA-ABC, HLA-DR, CD86, CD54 and CD83, CD1a.DCs can increase about 1.7 times proliferation of TILs.The cytotoxicity of TILs stimulated with DCs was increased from (31.80±14.05)% to (51.89±13.27)%. Conclusion The mature DCs can be induced from malignant pleural effusions from patients with lung cancer.The DCs can stimulate TILs from the origin malignant pleural effusion and increase its proliferation ability and cytotoxicity to cancer cells.