Extensive characterization of dendritic cells generated in serum-free conditions: regulation of soluble antigen uptake, apoptotic tumor cell phagocytosis, chemotaxis and T cell activation during maturation in vitro

Dendritic cells (DC) play a key role in the initiation of primary immune re sponse, and pilot clinical studies have demonstrated their ability to induc e efficient antitumor immunity. However, the DC used in these clinical tria ls were generated with various serum sources and were poorly characterized. Obtaining fully characterized DC in controlled and reproducible culture co nditions is thus of major interest. We demonstrate that X-VIVO 15 medium su pplemented with 2% human albumin can be used to obtain DC. The phenotypic a nd functional characteristics of these clinical-grade DC were analyzed acco rding to their differentiation stages. CD83(-) immature DC, obtained in the presence of granulocyte-macrophage colony-stimulating factor (GMCSF) and i nterleukin (IL)-4, were able to endocyte soluble antigens and internalize a poptotic tumor cells, and also expressed receptors far inflammatory chemoki nes. Tumor necrosis factor-alpha (TNF-alpha) induced irreversible DC matura tion in association with a decreased ability to uptake antigens and an incr eased allostimulatory capacity. CD83(+) mature DC became responsive to EBI1 ligand chemokine (ELC), a chemokine specifically expressed in secondary ly mphoid organs. In addition, mature DC obtained with TNF-alpha produced IL-1 2 and some IL-10 in response to CD40 stimulation. In conclusion, we present well-defined culture conditions allowing the control of DC maturation for clinical or fundamental studies.