If a piece of life tissue of a person is grafted to another person, after a short period the transplanted tissue will be disintegrated and disappear. Also in most infectious diseases , the victim will be resistant against the malady after recovery. Such body responses are are called Immunological reactions and the study of these reactions, mechanisms involved and related consequences is known as Irnmunology. Of the most important applications of Immunology are disease prophilaxy (through vaccination), diagnosis and treatment......