In the kingdom of the human body, every cell lived in harmony by doing its own functions in a perfectly balanced way. I can say that the kingdom of the human body was very peaceful and also its resident organs, cells and tissues were very happy. As any other happy kingdom, there was a constant fear of external invaders like bacteria, viruses, worms, toxins and allergens. To fight these invaders the kingdom thought to construct a formidable army and this is the story of that army and its war against pathogens, people called this lovingly as THE IMMUNE RESPONSE. This is the story of the construction, action, soldiers, battlefields, strategy and betrayal where I am going to describe the most specific, fine-tuned and strategically advanced warfare.
Chapter 1 – The Introduction
On the first day when the great kingdom of the human body was born, the citizen cells of it were very concerned for their safety against invaders as on day one they did not have an army of fight the war against pathogens. Luckily some of the cells said that they could fight against the pathogens but there were two problems. Firstly they could last only for a few days in the war and secondly, they were not very good in recognizing the pathogens with minute differences and have a similar strategy of fight every time. The remaining cells of the kingdom were very happy to know that some people who can take part in the war and had the inborn ability to fight. They have gathered those cells, created the battalion and given the name to this battalion “The Innate Immunity (The immunity which is present by birth). After the construction of the first battalion, the kingdom decided to recruit and train new cells to become those soldier who could fight in the war until the invaders are killed and also those soldiers could recognize different pathogens very specifically. That is how the second battalion was created which was specific and long-lasting and the name given was “The adaptive Immunity”.
Now have a look at different types of soldiers of the great army of the kingdom of the human body-
- Neutrophils – An important member of the battalion Innate immunity, could perform the phagocytosis (Eating up the pathogen) and could start the pathways to kill the bacterial enemies.
- Eosinophils – Could kill the pathogens and also important in action against the enemies which were parasitic in nature.
- Basophils – Member of a squad which was specialized in recognizing the enemy agents which could cause chaos in the kingdom by inducing allergic reactions.
- Macrophages – A multitalented soldier who worked for both innate immunity and adaptive immunity. Specialist in phagocytosis and a very good agent who could capture the enemies and presented them to our adaptive immunity soldiers the T cells for their training as well as for combat missions ( Antigen presentation).
- Dendritic cells – One of the most important members of battalion the adaptive immunity, one of legend who was key for whole training of soldiers of adaptive immunity and it did this work by being one of the best in antigen presentation.
- Mast cells – Another category of specialized squad member from innate immunity who could create an environment in the battlefield with fire, heat and chemical bombs which made the invaders rub for their life (Inflammatory Response).
- T Helper -lymphocytes – a 1st special member of adaptive immune response squad, They contained a surface protein to recognize the very minute difference between the pathogens. The surface protein is called a T cell receptor and with the help of it, they created a diverse array of strategies against different pathogens by making chemical weapons called cytokines.
- T cytotoxic lymphocytes – a 2nd special member of adaptive immune response squad, They contained a surface protein to recognize the very minute difference between the pathogens. The surface protein is called a T cell receptor and with the help of it, they created a diverse array of strategies against different pathogens by making chemical weapons called Granzyme and Perforins. They were brutal soldiers who were famous to kill own cells if pathogens were hiding there (Cytotoxicity).
- B lymphocytes – a 3rd special member of adaptive immune response squad, They contained a surface protein to recognize the very minute difference between the pathogens. The surface protein is called as B cell receptor or surface immunoglobulins and with the help of it they created a diverse array of strategies against different pathogens by making chemical weapons called as antibodies.
- Regulatory T cells – In the army, there were always some rogue elements who tried to kill or destroy members of own kingdom, to control them a very important group was there which is called as Regulatory T cells or suppressor T cells. (Immune tolerance and autoimmunity prevention).
- Natural Killer cells – Very aggressive group of soldiers specially designed for equally dangerous viruses. They also showed the same amount of brutality as Cytotoxic T cells in killing their own cells if pathogens were hiding there (Cytotoxicity).
Other than specificity and longevity of the response the battalions of innate immunity and adaptive immunity were different from each other based on their requirements. As the soldiers from Innate immunity were ready to fight from birth so they did not require the training grounds but the case of soldiers from adaptive immunity was different. The basic principle behind the construction of army related to adaptive immunity was that the soldiers will learn and adopt for war techniques by exposing them towards different invaders in the training grounds. Since they had the requirement of training so the kingdom has decided to give specific places to lymphocyte soldiers of adaptive immunity.
- Bone marrow – A place where B lymphocytes were developed and matured.
- Thymus – A ground where T lymphocytes were developed and matured.
- Lymph nodes, Spleen, Different mucosal layers and blood – All these places behaved as training grounds and also battlegrounds for adaptive immune response.
- Invaded tissue spaces – These places behaved as final battlegrounds.
To be continued…
Dr. Nishant Vyas
Post Doc, Stem Cell Research