Immune System

The immune system is a complex network of cells, tissues, and organs that helps the body fight infections and other diseases. The immune system includes skin, which can help prevent germs from entering the body; mucous membranes, which are the moist, inner linings of some organs and body cavities; white blood cells, which fight germs; and organs and tissues of the lymph system, which produce, store, and carry white blood cells. Disorders of the immune system include allergies, asthma, autoimmune diseases, and immunodeficiency diseases.