Dendritic cells (DC) are professional antigen-presenting cells that are specialized in the uptake of antigens and their transport from peripheral tissues to the lymphoid organs. Because of their capacity to stimulate naïve T cells, DC have a central role in the initiation of primary immune responses and are considered promising tools and targets for immunotherapy. Investigating the signals that regulate the function of DC, the sentinels of the immune system, is also critical to understanding the role of DC in the regulation of immune response. We have assessed the effects of natural antibodies in the form of therapeutic intravenous immunoglobulins (IVIg) on the regulation of the function of DC. We have observed that DC are the primary targets for the immunosuppressive effects of IVIg on T-cell activation. This review focuses on the effects of IVIg on DC development and function. © 2005 S. Karger GmbH.