Effects of vasoactive intestinal peptide on phenotypic and functional maturation of dendritic cells

The present study was designed to investigate the effects of vasoactive intestinal peptide (VIP) on differentiation, maturation of dendritic cells (DCs) in vitro. DCs were derived from the murine bone marrow hemopoietic progenitor cells by culturing in RPMI 1640 complete medium supplemented with GM-CSF and IL-4 in the presence or absence of various concentrations of vasoactive intestinal peptide (VIP) and lipopolysaccharide (LPS). The phenotype of DCs was analyzed by flow cytometry. Mixed leukocyte reaction (MLR) was employed to measure the capacity of DC to stimulate the allogeneic T cells. IL-12p70 secretion by DC was examined by ELISA. In the absence of LPS, VIP, in a dose dependent manner, up-regulated the expression of CD80, CD86, CD54 and CD40, but down-regulated the expression of MHC class II molecule (Ia(b)). In the presence of LPS, VIP also dose dependently up-regulated the expression of CD80, CD86, CD54 and CD40, and down-regulated the expression of Ia(b). The capacity to stimulate alloreactive T cells and the production of IL-12p70 by DC were significantly augmented by VIP when compared with VIP-untreated DCs. These data suggest that VIP could promote the phenotypic and functional maturation of DCs, hereby regulating the type and outcome of the conducting immune response.