Defense Of Human Immune System Against Antigen

Zainab Sarfraz

Defense Of Human Immune System Against Antigen

Immunization is the process by which the person body or immune system become immune or resistant to the infectious agent. Infectious agents that invade in the body of the living organism are known as the immunogenic. Our immune system work as a tool for controlling and eliminating the life-threatening infectious diseases that may cause the death of 2 to 3 million people each year. Edward Jenner discovered the smallpox vaccination. Louis pasture develops immunization method for chicken cholera and anthrax in animals and for human rabies.

When germs such as bacteria or viruses invade the body, they multiply, attack the cells and cause illness to the healthy person called infection. The immune system consists of immune or white cells such as B lymphocytes, T lymphocytes and macrophages. White blood cells are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. Macrophages are white blood cells that swallow up and digest germs, dead cells. The macrophages leave behind parts of the invading germs called antigens. The body identifies it as dangerous and stimulates the body to attack them. Antibodies attack the antigen left behind by macrophages. Antibodies are produced by defensive white blood cells called B-lymphocytes.

T-lymphocytes are the other type of defensive white blood cells. They attack the germ cells in the body that have already been infected such as cancerous cell. When germs enter in the body and immune cells encounter and destroy those germs, it can take several days to get over the infection. After the first time of encounter, our immune cells acknowledge how to protect body from disease. Few T-lymphocytes known as memory cells undergo quick action if body encounter to the germ again and immune system does not require several days to make defense cells.

Active immunization occurs when pathogen such as bacteria, viruses invade in the body and immune system produce B-cells and T-cells which show the active response to pathogen and memory B-cells and T cells produce. These memory cells present throughout the lifetime of the human and remember how to encounter the disease if the same specific pathogen enters the body which was previously invaded. When microbes or some part of microbe are injected into the person before the microbes naturally enter the person, then it means that we artificially introduce the active immunization in the person.

Passive immunization is introduced in the healthy individual in the form of antibodies to reduce the risk of getting the infected transfer from the other person who is actually infected from the germ. Passive immunity occurs naturally when maternal antibodies are transferred from the mother to the fetus with the help of placenta. It can also be induced in the human artificially when antibodies of human which is specific for the particular pathogen is introduced or injected to the healthy individual with having no particular antibodies for a specific pathogen.

When the environment is facing the recent outbreak of a particular disease which is transfer from one person to other or body is incapable to develop its immune response, then passive immunization is used to reduce the risk of infection. Passive immunity provides immediate protection from the ongoing disease. But the body is incapable of developing the memory cells, so the patient is at the risk of being infected by the same pathogen later.

How vaccines work…..

Vaccines prepare the body to fight against the disease without exposing it to the disease symptoms. When foreign invaders such as bacteria and viruses enter the body, immune cells called lymphocytes respond by producing the antibodies, which are protein molecules. These antibodies fight the invader which is known as antigen and protect against further infection. Healthy individuals can produce millions of antibodies a day, fighting infection so efficiently that people never even know they were exposed to the antigen. The first time the body faces a particular invader, it can take several days to produce antibody. In this situation, the infection can spread and kill the person before the immune system can fight back. For this purpose, vaccines are used. Vaccines are made of dead and weakened antigens. They cannot cause an infection because they are not active but the immune system still sees them as an enemy and produce the antibodies in response. When germs cell passed, antibodies will break down but some immune cells called memory cells remain active in the body throughout the lifetime.

When the body encounters that antigen again, the memory cells produce antibodies fast and strike down the invaders before it’s too late.

How Vaccines Fight Against Viruses:


Vaccination can protect people from polio( is a disease caused by a virus essentially spread by person-to-person contact, by consuming food or drink water that is polluted with the faeces of an infected person).

Infected people have no symptoms of polio, and many recover without complications. But sometimes people who have polio develop paralysis result in permanent disability. Polio can also cause death; usually by paralyzing the muscles that are involved in the breathing. Inactivated Polio Vaccine (IPV) can prevent polio. Most people should get IPV when they are children of 4 to 6 years of age.

Hepatitis B Vaccine:

To prevent hepatitis B is by getting the hepatitis B vaccine. The hepatitis B vaccine is protected and useful in 3-4 shots over a six month period. All children get their first dose of hepatitis B vaccine at birth and complete the vaccine series by 6-18 months old. Hepatitis B vaccine is recommended for all babies to prevent disease. Babies and young children reduce the risk of developing a chronic infection by using infection.

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