The human immune system has evolved to recognise and destroy potentially harmful substances, protecting the body from cancers and infections in healthy individuals. The immune system recognises antigens, which are substances that induce an immune response in the body. These antigens can be exogenous antigens derived from foreign sources (such as pollen, food, viruses or bacteria) or endogenous antigens (self-antigens), which are produced by the body (such as human protein).
To function effectively, the immune system must discern between harmful antigens and innocuous antigens. The immune system maintains a delicate balance between effector cells, which mount immune responses to antigens that represent potential threats, and regulatory cells, which mitigate undesired and potentially harmful immune responses through suppressive mechanisms. Depending upon the characteristics of the antigen and the context in which the antigen is encountered, the immune system must determine whether to mount an aggressive (effector) or regulatory (tolerogenic) immune response.
Autoimmune diseases occur when the immune system mounts an undesired response to an innocuous self-antigen, such as the components of the myelin sheath in the case of MS or the thyroid stimulating hormone receptor ("TSHR") in the case of Graves' disease. Autoimmune diseases are chronic, incurable6 conditions which are treated with therapies that often have serious life-threatening or life-altering side effects and do not address the immunological basis of the disease.
An estimated 50 million people suffer from autoimmune disease in the US alone5, and it is one of the leading causes of death in women in the US in all age groups up to 65.6 Furthermore, the incidence of autoimmune disease has been growing annually. At least eighty types of auto-immune diseases exist.1 Annual invoice spending in the US on autoimmune diseases (excluding diabetes) has increased by 145% from $15.2 billion in 2012 to $37.2 billion in 2016 (reflecting a 25% CAGR).7
1 Office of Women’s Health US
5 American Autoimmune Related Diseases Association
6 American Journal of Public Health. 90 (9): 1463–6 4. N Engl J Med. Sep 2002 347(12):911–920
7 QuintilesIMS, 2016