Dendritic cells are the sentinels of the immune system. Their job is to detect and uptake antigens in areas such as the skin and blood. An antigen is defined as any foreign material that can be recognised by the immune system. Upon uptake of an antigen, dendritic cells must travel to a lymph node to present the antigen to T cells. This presentation along with other signals results in a T cell response against that antigen. Dendritic cells therefore help to generate an adaptive immune response.