Immunity is the ability of the living body or the processes thereof to resist various types of organisms or toxins that tend to damage the tissue and organs. Immune response is a reaction or response that occurs in the body against a great variety of foreign organic macro molecules. The immune response is referred to as allergy or hypersensitivity in many instances. There are four characteristics of immune response:
- Discrimination: Immunity has an ability to differentiate between the self or non self or foreign material. An immune response is produced only against foreign body.
- Specificity: Immunity system is highly specific. It can recognize not only different species but also different strains or forms of organisms.
- Anamnesis: this is an ability to elicit a large specific response more quickly when induced by a second exposure to the same foreign body.
- Transferability by living cell: immune response can be transferred from one inbred animal to another by immune cells or lymphocytes.
Immune system is not transferred through serum.
Components of Immune System:
Immune system involves “Integrated cellular system” that includes antigen, antibodies lymphocytes and those which are sensitized with antigen, antibodies macrophage, neutrophis, basophils, monocytes.
Antigen is a substance that is capable of including antibody formation or reacting with the(if already present). Antigen is highly specific in reflecting as foreign and immunogenic .An antigen has two parts –hapten (a low molecular weight part that determines by specificity) and carrier (a high molecular weight part that initiates response). Antigen can be tissue specific e.g. agglutinogens of blood group. Bacterial toxins etc. also has antigenicity properties.
Antibodies are gamma globulins or immunoglobulin’s produced in the serum on exposure to antigen. Chemically they are glycoprotein’s containing two heavy chains and two light chains joined together by disulfide bonds. Antibody has two part produced are The function of antigen binding whereas the other part participates in producing response (immune response). The entire antibody structure can be cleared by papain, proteolysis enzymes.
There are five types of antibodies
IgG antibody:-can produce anaphylaxis seen in extra vascular fluids.
IgM antibody:-seen in vascular system. Most effective as agglutinin
IgA antibody:-found in serum, saliva tears, G.I secretions and bronchial secretion. Effective against viruses.
IgE antibody: – causes release of histamine from mast cells i.e. produces sensitization.
IgD antibody:- present in the surface of lymphocytes.
This is a multimolecular self assembling biological system which constitutes the primary humoral medicator of antigen- antibody reactions. complement system is a group of eleven plasma proteins that circulate in the blood. Each of them consists of nine components (C1-C9) with three main subfractions of the first participating in the immune response leading to the destruction of foreign invaders. Once the antigen antibody complex is formed, the complement system gets activated and results in enhancement of inflammatory response by causing vasodilatation and vascular permeability, attracting neutrophils and mast cells to the site of invasion, coating the surfaces of micro organisms so as to enhance the possibility of their phagocytosis.