Immune system: Definition, types, antibodies, immunisation, etc.

IMMUNE SYSTEM

Immune system

The immune system is a main defense system consisting of  many biological structures and processes within an organism that protects against disease.Even simple unicellular organisms such as bacteria possess a basic immune system in the form of enzymes that protect against bacteriophage infections.

It is the third line of defence against the harmful microbes or molecules.Its one of the important characteristic is that it can recognise its own cells(self) or micromolecules and outer invadors(non-self).This is a system which involves a complex system of cells and tissues that helps us to provide immunity against any disease.

IMMUNITY

Immunity is the ability of an organism to recognise the foreign materials (non-self or antigens) that enter the body and to mobilise the cells or cell products to speedily remove those foreign materials or antigens.

KINDS OF IMMUNITY

There are two types of immunity.These are as follows:

Kinds of immunity

1. INNATE IMMUNITY-Some disease can not occur in certain organisms,as the antibodies are inherited from their parents against the antigens.The disease can not grow in those organisms for lifetime.They are protected since the time of birth.For example,in humans the viral disease,distemper can not occur.
2. ADAPTED IMMUNITY-This type of immunity is developed in the body during the production of antibodies in the blood in response to the antigens or the entry of the mirobes. The formation of antibodies start when the microbes invade into the body.During the first time of infection the disease may appear as the speed of formation of the antibodies are slow.After the the formation of the antibodies the the disease disappears.Afterwards the antibodies remains in the body and provides an immediate protection from the particular disease.Again the adapted immunity has two classifications.Those are follows:

•  Natural immunity-These type of adapted immunity is developed in the body automatically when the infected person is recovered from the disease.The antibodies of that  disease remains in the body for the whole life.If anytime the particular type of disease is seen in the particular person then his immune system can combat immediately by those antibodies.
•  Artificial immunity-These type of immunity is achieved by the introduction of the weak or dead microbes of particular disease or by injecting antitoxins of a prepared serum.Again the artificial immunity  is classified into two forms. They are follows:

(i)Active immunity

Active immunization is the induction of immunity after exposure to an antigen. Antibodies are created by the recipient and may be stored permanently.Active immunization can occur naturally when a microbe or other antigen is received by a person who has not yet come into contact with the microbe and has no pre-made antibodies for defense. The immune system will eventually create antibodies for the microbe, but this is a slow process and, if the microbe is deadly, there may not be enough time for the antibodies to be used.

(ii)Passive immunity

Passive immunity is the transfer of active humoral immunity of ready-made antibodies. Passive immunity can occur naturally, when maternal antibodies are transferred to the fetus through the placenta, and it can also be induced artificially, when high levels of antibodies specific to a pathogen or toxin (obtained from humans, horses, or other animals) are transferred to non-immune persons through blood products that contain antibodies, such as in immunoglobulin therapy or antiserum therapy.Passive immunization is used when there is a high risk of infection and insufficient time for the body to develop its own immune response, or to reduce the symptoms of ongoing or immunosuppressive diseases.Passive immunization can be provided when people cannot synthesize antibodies, and when they have been exposed to a disease that they do not have immunity against.

FACTS RELATED TO IMMUNE SYSTEM

(I) ANTIBODIES

Antibodies

An antibody, also popular as an immunoglobulin, is a large, Y-shaped protein produced mainly by plasma cells that is used by the immune system to neutralize pathogens such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the pathogen, called an antigen, via the fragment antigen-binding variable region.Each tip of the "Y" of an antibody contains a paratope (analogous to a lock) that is specific for one particular epitope (analogous to a key) on an antigen, allowing these two structures to bind together with precision. Using this binding mechanism, an antibody can tag a microbe or an infected cell for attack by other parts of the immune system, or can neutralize its target directly (for example, by inhibiting a part of a microbe that is essential for its invasion and survival). Depending on the antigen, the binding may impede the biological process causing the disease or may activate macrophages to destroy the foreign substance. The ability of an antibody to communicate with the other components of the immune system is mediated via its Fc region (located at the base of the "Y"), which contains a conserved glycosylation site involved in these interactions.The production of antibodies is the main function of the humoral immune system.

(II) IMMUNIZATION

Immunization

Immunization is the process whereby a person is made immune or resistant to an infectious disease, typically by the administration of a vaccine. Vaccines stimulate the body’s own immune system to protect the person against subsequent infection or disease.

Immunization is a proven tool for controlling and eliminating life-threatening infectious diseases and is estimated to avert between 2 and 3 million deaths each year. It is one of the most cost-effective health investments, with proven strategies that make it accessible to even the most hard-to-reach and vulnerable populations. It has clearly defined target groups; it can be delivered effectively through outreach activities; and vaccination does not require any major lifestyle change.

(III) DISINFECTION

Disinfection

DISINFECTANT

Disinfectants are antimicrobial agents designed to inactivate or destroy microorganisms on inert surfaces.Disinfection does not necessarily kill all microorganisms, especially resistant bacterial spores; it is less effective than sterilization, which is an extreme physical or chemical process that kills all types of life.Disinfectants are different from other antimicrobial agents such as antibiotics, which destroy microorganisms within the body, and antiseptics, which destroy microorganisms on living tissue. Disinfectants are also different from biocides — the latter are intended to destroy all forms of life, not just microorganisms. Disinfectants work by destroying the cell wall of microbes or interfering with their metabolism. Sanitizers are substances that simultaneously clean and disinfect.Disinfectants kill more germs than sanitizers. Disinfectants are frequently used in hospitals, dental surgeries, kitchens, and bathrooms to kill infectious organisms.

ANTISEPTICS

Antiseptics are antimicrobial substances that are applied to living tissue/skin to reduce the possibility of infection, sepsis, or putrefaction. Antiseptics are generally distinguished from antibiotics by the latter's ability to safely destroy bacteria within the body, and from disinfectants, which destroy microorganisms found on non-living objects. Some antiseptics are true germicides, capable of destroying microbes (bacteriocidal), while others are bacteriostatic and only prevent or inhibit their growth. Antibacterials include antiseptics that have the proven ability to act against bacteria. Microbicides which destroy virus particles are called viricides or antivirals. Antifungals, also known as an antimycotics, are pharmaceutical fungicides used to treat and prevent mycosis (fungal infection).

STERILIZATION

Sterilization refers to any process that eliminates, removes, kills, or deactivates all forms of life (in particular referring to microorganisms such as fungi, bacteria, viruses, spores, unicellular eukaryotic organisms such as Plasmodium, etc.) and other biological agents like prions present in a specific surface, object or fluid, for example food or biological culture media. Sterilization can be achieved through various means, including heat, chemicals, irradiation, high pressure, and filtration. Sterilization is distinct from disinfection, sanitization, and pasteurization, in that those methods reduce rather than eliminate all forms of life and biological agents present. After sterilization, an object is referred to as being sterile or aseptic.

(IV) ANTIBIOTICS

Antibiotics

An antibiotic is a type of antimicrobial substance active against bacteria and is the most important type of antibacterial agent for fighting bacterial infections. Antibiotic medications are widely used in the treatment and prevention of such infections. They may either kill or inhibit the growth of bacteria. A limited number of antibiotics also possess antiprotozoal activity. Antibiotics are not effective against viruses such as the common cold or influenza[citation needed]; drugs which inhibit viruses are termed antiviral drugs or antivirals rather than antibiotics.