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The body's immune system: A double-edged sword

Read time: 2 mins

Our body has a personal army of dedicated soldiers ready to defend us all the time—our immune system. Its combatants can fend off simple infections like a common cold or a sore throat, as well as life-threatening intruders like Mycobacterium tuberculosis, the bacteria which causes tuberculosis, or the virus that causes hepatitis. However, sometimes, the cells in our immune system go berserk and find an enemy within—they start attacking cells in our body!

What triggers our immune system to act? It could be anything foreign or toxic to our body. Collectively called antigens, they are mostly some form of proteins or carbohydrate. The immune system identifies these antigens and produces antibodies to get rid of them. Our cells, which also are made up of proteins and carbohydrates, escape the action of these soldiers due to the presence of specific distinguishing features called "self-antigens". The immune cells, during their development in the thymus and bone marrow, are exposed to these self-antigens and made tolerant to them. In a healthy individual, these tolerant cells go on to mature and become cells of the immune system. The body destroys the intolerant ones.

Many times, due to discrepancies in this process of destruction, the autoreactive immune cells escape the surveillance and can cause autoimmune disorders. These discrepancies can be genetic in origin, or there could be a mutation in the self-antigens, or excessive and uncontrolled inflammation can lead to an overactive immune system.

These autoimmune disorders can be organ-specific or systemic. Organ-specific autoimmune disorders, as the name suggests, is caused when autoreactive cells attack a specific tissue or organ, such as the pancreas in Type 1 diabetes, thyroid in Hashimoto's hypothyroidism or Grave's disease, and gut tissues in ulcerative colitis or irritable bowel syndrome. Systemic autoimmune disorders occur when the effect of the autoreactive cells are seen all over the body, in conditions like lupus, rheumatoid arthritis, multiple sclerosis and ankylosing spondylitis.

There are more than eighty types of autoimmune disorders that have overlapping symptoms, making it hard to diagnose. Treatments usually include immune suppressants, which reduce the overactivity of the immune system. Sometimes, anti-inflammatory drugs like ibuprofen or certain steroids are given to limit excessive inflammation. The origins of these autoimmune disorders remain a mystery, and the mechanisms to understand the self-sabotaging nature of our immune system have only been hypothesised.