Passive Immunity: Definition, Function, and Examples

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Passive Immunity Definition

Resistance to a disease or toxin gained without the immune system producing antibodies is known as passive immunity. Any foreign body including a virus or toxin harms an organism’s cells. In this condition, both active and passive immunity develops an organism’s body to preclude this outcome.

An organism has passive immunity in its body from birth. It helps to stop any malicious foreign body and uses various methods for this. Passive immunity acts as a barrier that prevents harmful substances from attacking the organism’s sometimes also attacks invaders directly as an untrained cell.

The organisms pass the antibodies from one to another by many natural and artificial methods. The fetus gets a passive immunity in the form of antibodies from its mother via the umbilical cord. These antibodies help the newly developing baby to fight infectious agents and protect itself from infections until the baby develops its strong immunity system to provide an active immunity to the same infection.

There are many forms of passive immunity, such as the barriers that separate the internal and external of the organism, and divisions that separate the bloodstream from critical areas including the brain. Organisms use many other methods of passive immunity including genetic immunity to provide antibodies.

Passive Immunity Examples

i. Skin as a Passive Immunity

Skin is a fundamental form of passive energy in most animals. Many layers of flattened cells form the skin. These cells make an almost impenetrable surface by forming a bond between each other. The shin does not allow any virus, or bacteria to penetrate from it but the small size of these infectious agents get the advantage of even a microscopic tear in the skin that allows thousands of bacteria, viruses to enter through it.

Active immunity is produced in case of the failure of passive immunity that helps in fighting against the bacteria and viruses and restricts their reproduction and the spread of toxins. The skin has a significant role in protecting the body from the constant bombardment of environmental dangers every day.

Toxins, the disease could be easily absorbed directly from the air, water, and soil if the skin is not present. Skin establishes a barrier between internal organs and environmental dangers such as pathogens and provides one passive immunity for a variety of harmful bodies and infectious agents as well.

However, we can be in trouble if a large amount of toxin gets through the skin. In that condition, passive immunity helps in blocking a toxin or disease before it enters our system, and resistance to the disease is developed by the active immunity after initial infection.

ii. Anti-venom is a Passive Immunity

We could be injected with the snake’s venom if a rattlesnake bites us. The venom of the rattlesnake is hemotoxic. It destroys the tissues and affects the clotting tendency of the blood and doesn’t allow the blood to clot which results in bleeding.

Our body will gain the ability to produce antibodies against it if the venom is exposed in a small amount, and we would eventually be able to survive small doses of the venom. However, in most cases, a large amount of venom is injected by the rattlesnake into the wound. In this case, an anti-venom is administrated to the body for survival.

A high number of venom antibodies, proteins having the ability to bind to the venom are present in these serums. The serum removes the venom from the bloodstream and tissues. The antibodies of anti-venoms are usually created in live animals and collected for use in humans therefore they are quite expensive to produce.

iii. Passive Immunity in Bacteria

Some bacteria can incorporate foreign DNA into their systems. Usually, they did this to increase their rate of reproduction and get an advantage over other bacteria. Antibiotics are also a threat to bacteria.

Antibiotics destroy bacterial DNA or deprive it of a food source in different ways. The bacteria become able to reproduce due to mutations that counteract the antibiotics. These bacteria leave remnants of the DNA after their death that allow other bacteria to survive.

The remnants of these bacteria are incorporated by other bacteria into their DNA. The way is much similar to the passive immunity gain by a baby by its mother.

Passive Immunity Citations
  • Passive immunity in rotaviral infections. J Am Vet Med Assoc . 1978 Sep 1;173(5 Pt 2):565-8.
  • Active and passive immunization for cancer. Hum Vaccin Immunother . 2014;10(7):2123-9.
  • Active and passive immunity, vaccine types, excipients and licensing. Occup Med (Lond) . 2007 Dec;57(8):552-6.
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