Imagine that there is a much flourished country divinely blessed with natural resources, enriched culture (It is said that India was like this, once upon a time) Suddenly some enemy invades and destroys, exploits the land..so what is the use? Even an idiot will say that there must be an equally powerful defense system to protect all that flourished land.

                    Our body is also like that of the same land. It is much nurtured, powerful system, smoothly running for years together. But there are too many micro-organisms that are in search of such environment, where they can get entry and can multiply in numbers. Hence it is obvious that they must be having a powerful mechanism and machinery to get “enrolled” in the body.
                    But if any organism’s progenies are continued throughout the eras, there must or should have been a powerful mechanism that is constantly and successfully fighting with such micro-organisms so that it can continue with the progenies. This mechanism is nothing but “immunity”.
                    A very important part of the immunity system must be self and non self recognition; otherwise as soon as the infection occurs, the body would start fighting with itself instead of fighting with that of the invader! Hence there must be the “weapons” that are very specific, precisely formed towards each and every invader. Such weapons are called antibodies. It is analogous to the concept of different kinds of pistols, guns, and bombers etc. that are used against respective types of enemies as and when needed.
                   Some part of this immunity is formed far before birth and it is called as Innate immunity. It is actually in the form of “barriers” like physical, Physiological etc. with the help of which the body can actually keep distance from some invaders or infections.

                  But what about the baby that is just born and its body does not know the various types of invaders that it comes across? For this, the weapons i.e. the antibodies are made as and when the “order” is placed by the body. But when is this order placed?- when there is very first infection. If the pathogen is not successful in forming the infection (because of enough antibodies produced quickly), fine, if yes, it is the “lesson” for the baby’s body and it forms the antibodies as a part of “memory” and if there is next infection, the body is ready to fight with it without even being noticed!(Natural acquired active immunity) This is how we become immune year by year and do not show diseased condition every now and then. (of course, this risk factor is not advisable for the dangerous and disabling or life threatening diseases like Polio, Tetanus etc. and hence, the immunization is provided to the babies via vaccination and is called as artificial acquired active immunity.)

                   The baby can also received “readymade” antibodies from the mother while it is in her womb and then it is called natural acquired passive immunity. If such antibodies are introduced after birth, it is called artificial acquired passive immunity. For the synthesis of such antibodies, the blood serum of humans, horses is needed.

                   Who synthesizes these antibodies? The factories are Plasma cells. In immunity, some cells- the famous WBCs or leucocytes are also involved. Out of them, the lymphocytes are important that either attack the pathogens directly (T-lymphocytes) or produce the antibodies (B-lymphocytes). In all this, the antigen presenting cells help the antibodies to recognize the antigen so that they can readily attack them.

                   An antibody is made up of protein chains, formed differently to attack unlimited types of antigens. The specificity in their structure is according to the molecular structure of the antigen. The combination of antigen and antibody neutralizes the antigen; it is called antigen antibody complex. Thus, to destroy an antigen, an antibody has to scarify its life just like a soldier.
                   This principle is also applicable in blood group system also. That is why the specific blood group can or cannot be mixed with the other one.

                   The immunity system, if is showing some abnormalities, they are shown in the form of immunological diseases like allergy, AIDS etc. The body shows hypersensitivity towards a physical or chemical agent via production of some substances and this leads to rash or some other conditions against the body itself. Such agents may be pollens, dust etc.

                   What if the cells of immunity are destroyed or infected specifically? Such condition is there in case of AIDS, in which the HIV attacks T-Helper cells, and if any simplest infection like flue occurs, the cell becomes “factory” of the HIV instead of fighting with that pathogen!

                  Thus we can imagine how important this Immunity system is. We can learn the principles of specificity, preciseness, self non self recognition and most importantly after that- “fighting spirit”!! 

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• MHT-CET