In a healthy person, the immune system essentially protects the body from foreign bodies like bacteria, virus, and other germs. This is enabled by the ability of the immune system to make a clear distinction between foreign cells and the body’s own cells.
The immune system of a person suffering from an autoimmune disease fails to differentiate between healthy cells and foreign cells. As a result, it releases antibodies as part of its defense mechanism. Antibodies are the proteins released by the immune system to attack foreign bodies. However, in the case of an autoimmune disease, these antibodies attack healthy cells of the body.