The most exceptional feature of our immune system is its ability to tell apart components of the body from foreign invaders and to selectively neutralise the threat. This ability of the immune system protects us from pathogens entering our body on a day to day basis. In case our immune system loses this very ability to differentiate and starts attacking self entities instead, wouldn’t that be like activating a self destruct mode in the body?
When the immune system inappropriately starts attacking cells, tissues and organs of the body itself, the condition is termed autoimmunity. Paul Ehrlich was the first one to realise that the immune system could go askew, and start attacking itself instead of focusing on foreign entities. He termed this state Horror autotoxicus. The immune system in our body operates via two pathways — humoral immunity and cell mediate immunity. The former employs antibodies (specialised proteins) to tackle the foreign pathogens in the body whereas the latter recruits reactive (T) cells for the same. Both antibodies and reactive T cells can elicit an autoimmune reaction in the body. Autoimmunity can result in chronic debilitating diseases, categorised broadly into organ specific and systemic autoimmune diseases.
Organ specific autoimmunity results due to a targeted attack against a self antigen exclusive to a particular organ or gland. Antibodies or cells reacting against the self antigen can over stimulate or completely block the function of that organ/gland. The cells and antibodies acting against self antigens induce an inflammatory response or death of cells thereby compromising organ function. Since, the attack is restricted to one particular organ or gland, the manifestation of the condition is largely limited. Insulin dependent diabetes mellitus, Myasthenia gravis, Graves’ disease are instances of organ specific autoimmune diseases.
Insulin dependent diabetes mellitus (IDDM) arises as a result of an autoimmune attack on the pancreas, specifically against insulin producing beta cells within the islets of langerhans present throughout the pancreas. Destruction of beta cells affects insulin levels in the body with the subsequent inability to maintain blood glucose levels ending up in the development of a diabetic condition.
On the other hand, systemic autoimmune response is more of a self destruct mechanism where multiple and wide range self antigens and entities are targeted by a hyper active immune system by means of auto antibodies, reactive cells and numerous immune complexes. Systemic autoimmunity surfaces due to defective regulation of the immune system and its responses. The detrimental consequences and damage caused are often widespread.
Systemic lupus erythematosus (SLE), multiple sclerosis and rheumatoid arthritis are a few examples of a systemic failure in immune regulation due to auto immune response.
Rheumatoid arthritis is a common autoimmune disorder affecting people aged above 40 years, especially women. In this disorder, auto antibodies called rheumatoid factors are produced that form immune complexes which in turn are deposited at the joints. These immune complexes induce hypersensitive reactions leading to chronic inflammation at the joints.
Research has enabled scientists to study and understand that autoimmunity develops as a result of multiple events. Failure in an ideal development of the immune system (i. e. ability to distinguish between self and non-self), stray or previously unexposed self antigens entering immune system, foreign entities mimicking self antigens (molecular mimicry) are a few of the reasons linked to pathogenesis of auto immune activity.
Susceptibility to autoimmunity is a result of genetic factors, environmental factors and sex, i. e. women are found to be more susceptible to autoimmune responses and hormonal differences that have been attributed to this discovery. Treatment for autoimmune diseases involves the use of immunosuppressants in order to curb the attack by the immune system, anti-inflammatory elements to alleviate inflammation, dietary modifications and other immune modulatory therapies. Oral antigens are administered to establish immune tolerance for that particular detrimental antigen in the body and minimise the damage caused by an autoimmune reaction.
The best way is to monitor oneself and immediately consult a physician on noticing signs of possible autoimmune reaction (for example, the appearance of a butterfly rash across the face in SLE) to start therapy.