Distinct effect of CD40 and TNF-signaling on the chemokine/chemokine receptor expression and function of the human monocyte-derived dendritic cells.

A key and limiting step in the process of human monocyte-derived dendritic cells (mDCs) for clinical use is their in vitro maturation and in vivo migration. We previously observed that CD40 signal facilitated human mDC growth and maturation. To further explore this process, mDCs generated with GM-CSF and IL-4 were co-cultured with apoptotic tumor cells for 24 hours, followed by incubating with anti-CD40 monoclonal antibody or TNF-alpha for 48 hours to generate mature DCs. The chemokine/chemokine receptor expression and functions of mature DCs upon various stimuli were determined. The expression of costimulatory molecules on apoptotic tumor cell-loaded mature DCs co-cultured with either anti-CD40 antibody (anti-CD40-DCs) or TNF-alpha (TNF-DCs) were up-regulated compared to immature DCs, consistent with the abilities of these cytokine to drive DC maturation in vitro. The mRNA levels of chemokines such as stromal cell-derived factor-1alpha (SDF-1alpha), EBV-induced molecule 1 ligand chemokine (ELC), and IFN inducible protein-10 (IP-10) in anti-CD40 activated DCs were increased and the dendritic cell-specific chemokine 1 (DC-CK1) was moderately up-regulated as compared with other mature DCs. The corresponding chemokine receptors CXCR4 and CCR7 of anti-CD40-DCs were significantly expressed. The CXCR3 expression on activated T cells stimulated by anti-CD40-DCs was also increased. Moreover, the anti-CD40-DCs had a stronger ability to stimulate T cell proliferation than any other DCs. The NF-kappaB activity was much higher in anti-CD40-DCs than that of TNF-DCs. These results offer further evidence of the importance of the CD40 signal in developing efficient human DC vaccines for cancer immune therapy.