Autoimmune diseases are those diseases in which the white blood cells that are responsible for protecting the body from outside attacks fail to tell the difference between the antigens and the healthy tissue.

Antigens are substances that attack the body. Examples of antigens are viruses, bacteria, toxins and cancer cells.

When the immune system mistakenly attacks the healthy tissue, it results in inflammation in that area. The exact causes of autoimmune diseases are not known in several cases. It is believed that the immune system attacks the normal body molecules that are similar to the molecules of a virus.