An autoimmune disease is a condition in which your immune system mistakenly attacks your body. The immune system normally guards against foreign organisms such as bacteria and viruses. The immune system also has an important role in detecting abnormalities in the body’s cells which if unchecked can lead to cancers. There are many different ways in which the immune system protects us from infection and cancers.
Normally, the immune system can tell the difference between foreign cells and your own cells. In autoimmune diseases, the immune system mistakes proteins found in specific cells in part of your body — like your joints or skin — as foreign. It releases proteins called autoantibodies that attack healthy cells. This can establish an abnormal immune response with recruitment of many other types of immune cells, leading to tissue destruction.
Some autoimmune diseases target only one organ. For example, Type 1 diabetes damages the pancreas. Other diseases, like lupus, can affect many different types of tissue throughout the whole body.
Any tissue of the body can be affected in autoimmune disease, therefore many different symptoms are possible. Autoimmune diseases are frequently treated with medications that suppress the immune system (immunosuppressants) or change the immune system to be less inflammatory (immunomodulators).
There are many autoimmune diseases which are not primarily treated by immunologists, but immunologists may be consulted if there is a lack of response to standard treatments. Many autoimmune conditions can be treated by dermatologists, endocrinologists, neurologists, rheumatologists and ophthalmologists for instance without needing to see an immunologist. However, there are some conditions which are frequently primarily treated by an immunologist especially if they involve more than one system of the body (e.g. skin, nervous system, gut).