The immune system consists of the organs, cells, and molecules responsible for the recognition and disposal of foreign material which enters the body.
The immune system protects the body from disease by destroying pathogens that include bacteria, viruses, parasites, and fungi. The immune system does so by responding to antigens that are found on the surface of pathogens.
The cells of the immune system are white blood cells that are found in the bone marrow, lymph nodes, spleen, thymus, gastrointestinal tract, lung, and skin.
