Vaccines and the Immune System
- Antigen: a foreign substance which induces an immune response in the body
- Antibodies: proteins produced by the body in response to an antigen; antibodies combine chemically with antigens
- Phagocytes: cells of the immune system responsible for digesting and degrading pathogens
Vaccines work directly with the immune system to safely protect the body from the disease.
- Vaccines contain a killed or weakened form of a virus or bacteria, known as antigenic components, that are introduced to the body, either intranasally, orally, intradermally, or intramuscularly.
- Intranasally: administered by way of the nose (spray)
- Orally: administered by way of the mouth (pill, liquid)
- Intradermally: administered through the top layer of the skin
- Intramuscularly: administered through the muscle layer of the skin
- These antigens do not cause illness on their own. Instead, these antigens cause the immune system to mount a response. The response includes sending white blood cells to the site to destroy the invader.
- Some of these cells create antibodies that surround the antigen, acting like a signal for the other white blood cells to attack.
- Antibody:Antigen binding may result in:
- Agglutination: clumping together of antigens, which makes them more easily digested by phagocytes
- Neutralization: prevents the virus from attaching to receptors on our own cells
- Opsonization: coating of pathogens to enhance digestion by phagocytes
- Complement activation: causes inflammatory response to bring more immune cells to the infection site
- Antibody-dependent cytotoxicity: degradation of the infected cell
- Antibodies are produced against antigens in a lock-and-key fashion. You have billions of antibodies in your body against pathogens that you have seen since you were born!
Image Source: Boundless
- Memory cells of the immune system will remember the antigen, and will remain in the body for a long time.
- If the body encounters the same antigen again, the memory cells allow the immune system to mount a fast and effective immune response to destroy the antigen before it has the chance to cause illness.
Image Source: The Open Door Website
By previously being exposed to the harmless antigen in vaccines, you protect yourself from contracting the disease!