The immune system becomes stronger on exposure to different pathogens. By adulthood, most people have had exposure to a range of pathogens and developed more immunity.
Once the body produces an antibody, it keeps a copy so that if the same antigen appears again, the body deals with it more quickly.
Some diseases such as measles are severe if they occur. If a person has the measles vaccine, they are unlikely to get the disease.
If an unvaccinated person has measles once, it is also rare to get it again. In both cases, the body stores a measles antibody. The antibody is ready to destroy the virus next time it appears. This is called immunity.
There are two types of immunity in humans:
- innate
- adaptive
Innate immunity
People are born with some level of immunity that will attack invaders from day one.
This innate immunity includes Trusted Source the external barriers of our body — the first line of defense against pathogens such as the skin and mucous membranes of the throat and gut.
This response is general and nonspecific.
If pathogens manage to bypass the innate immune system, macrophages will attack them. Macrophages will also produce substances called cytokines, which increase the inflammatory response