Human dendritic cells induce tumor-specific apoptosis by soluble factors. Joo HG, Fleming TP, Tanaka Y, Dunn TJ, Linehan DC, Goedegebuure PS, Eberlein TJ. Department of Surgery and the Alvin J. Siteman Cancer Center, Washington University School of Medicine, St. Louis, MO 63110, USA. Dendritic cells (DCs) are the most potent antigen producing cells (APCs) for initiation of immune responses including anti-tumor immune responses. In previous reports, it has been shown that DCs efficiently take up and process apoptotic or necrotic bodies of tumor cells. It has also been shown that DCs pulsed with tumor cell apoptotic bodies, lysates or peptides generate potent anti-tumor immune responses. Direct interactions between DCs and viable tumor cells, however, have not been clearly elucidated. We report that monocyte-derived, CD1a+ immature DCs (iDCs) significantly inhibit the growth of breast tumor cells in coculture and transwell experiments in the presence of soluble CD40 ligand (sCD40L), LPS or both. The growth inhibition effects correlated with cell cycle arrest and apoptosis of breast tumor cells. The effects were associated with morphological changes of tumor cells from a round shape to a flat, spindle shape. In contrast, no inhibition of proliferation or morphological changes was observed on normal PBMC, K562 or breast fibroblasts. Interestingly, iDCs undergoing maturation induced by sCD40L+LPS induced a much stronger growth inhibitory effect than iDCs alone or mature DCs treated with sCD40L+LPS. Fractionation of supernatants showed the anti-tumor effects were mediated by a TNF-alpha-dependent and -independent mechanism. Soluble FasL and TRAIL were not involved. Our findings suggest that maturing DCs have the intrinsic ability to induce cell-cycle arrest and apoptosis of breast tumor cells through soluble factors, but not normal cells, in addition to their Ag presentation function. Int J Cancer 2002 Nov 1;102(1):20-8 Anticancer Res, 9-10/03 Abstract # 2527 ASCO, 2004 Intl J Cancer, 4/04 online Clin Cancer Res, 8/04 Remember we are NOT Doctors and have NO medical training. This site is like an Encylopedia - there are many pages, many links on many topics. Support our work with any size DONATION - see left side of any page - for how to donate. You can help raise awareness of CAM.