The human body contains 600 to 800 lymph nodes, which are specialized organs that trigger immune responses. To be informed about infections in the body, lymph nodes are connected to the individual organs via lymph vessels. From the organs, the lymph vessels transport fluids and special immune cells to the lymph nodes. These immune cells are called dendritic cells; they carry information from the organs into the lymph nodes and pass it on to other immune cells there.