The lymphatic system transports excess fluid and absorbs fats, helps defend the body against disease. It begins with lymphatic capillaries that drain into vessels containing valves, eventually draining into the thoracic duct or right lymphatic duct and returning to the bloodstream. Lymph is filtered from tissues and contains foreign particles that are transported to lymph nodes. The lymph nodes contain lymphocytes and macrophages that help fight infections. Adaptive immune defenses include lymphocytes that recognize foreign antigens and mount both cellular and humoral immune responses through T cells and B cells which produce antibodies.