Dendritic Cell Maturation and Subsequent Enhanced T-Cell Stimulation Induced with the Novel Synthetic Immune Response Modifier R-848

Agents that enhance dendritic cell maturation can enhance T-cell activation and therefore may improve the efficiency of vaccines or improve cellular immunotherapy. Previously, we demonstrated that a novel low-molecular-weight synthetic immune response modifier, R-848, induces IL-12 and IFN-α secretion from monocytes and macrophages. Here we report that R-848 induces the maturation of human monocyte-derived dendritic cells. Characteristic of dendritic cell maturation, R-848 treatment induces cell surface expression of CD83 and increases cell surface expression of CD80, CD86, CD40, and HLA-DR. Additionally, R-848 induces cytokine (IL-6, IL-12, TNF-α, IFN-α) and chemokine (IL-8, MIP-1α, MCP-1) secretion from dendritic cells. Most significantly, R-848 enhances dendritic cell antigen presenting function, as measured by increased T-cell proliferation and T-cell cytokine secretion in both allogeneic and autologous T-cell systems. Consequently, low-molecular-weight synthetic molecules such as R-848 and its derivatives may be useful as vaccine adjuvants or as ex vivo stimulators of dendritic cells for cellular immunotherapy.