Objective:To investigate whether pituitary adenylate cyclase-activating polypeptide(PACAP）can modulate the immune function of mouse LPS-stimulated dendritic cells.Methods: DCs were derived from bone marrow of C57BL/6 using rmGM-CSF and rmIL-4,then the DCs were exposed to different stimuli for indicated time periods.The stimulated DCs and their culture supernatant were subjected to ELISA and FACS analysis.The total RNA was extracted from the stimulated DC for RT-PCR and RNase Protection Assay.Results: PACAP significantly inhibited the production of IL-2,IL-12,TNF-α and MIP-2 in LPS-stimulated DCs (P<0.05,P<0.01,P<0.01,P<0.01,respectirely),but the inhibition of LPS-induced IL-6，MIP-1α and MIP-1β production was not apparent.Conclusion: PACAP can negatively modulate the immunity of LPS-stimulated DCs.