Novel immunosuppressive properties of interleukin-6 in dendritic cells: inhibition of NF-κB binding activity and CCR7 expression

SPECIFIC AIMSInterleukin-6 (IL-6) is produced during bacterial and viral infections and by various malignant tumors. Although characterized primarily as a proinflammatory cytokine, IL-6 has been proposed to have anti-inflammatory and immunosuppressive properties. The aim of the present study was to characterize the phenotype and determine the functional properties of dendritic cells (DC), central regulators of the immune response, under the influence of IL-6.PRINCIPAL FINDINGS1. IL-6 inhibits the chemotactic response toward CCR7 ligands in phenotypically mature dendritic cellsPeripheral blood monocytes were cultured with 100 ng/mL granulocyte macrophage colony-stimulating factor (GM-CSF) and 5 ng/mL IL-4 in the presence or absence of 100 ng/mL IL-6 for 8 days. Confirming previous studies, IL-6 impaired dendritic cell differentiation resulting in an intermediate phenotype with macrophage characteristics. However, activation of these cells with the maturation stimulus lipopolysaccharide (LPS) on day 6 not o...