The immune system defends the body
against infections and certain other diseases. It is made up of different organs,
cells, and proteins known as antibodies. It identifies, attacks, and destroys germs
and other foreign substances. Sometimes the immune system makes a mistake and attacks
the body's own tissues or organs. This is called autoimmunity. One example of an autoimmune
disease is type 1 diabetes, in which the
immune system destroys the cells in the pancreas that produce insulin.