About Immunity
The immune system protects the body from infections and diseases. It roots out germs and other attackers that shouldn’t be in the body, and it keeps a record of every invader that has been defeated so it can quickly recognize them again if they come back. This is called immunologic memory.
Immunity consists of cells, tissues and organs that work together to defend the body from germs and other invaders that cause illness. There are two basic types of immunity: innate and acquired (also known as adaptive).
Innate immunity is protection you’re born with. It enables your white blood cells to respond right away against any organism that doesn’t belong in the body. It does this without needing to learn about the invader or its proteins, like a gardener who doesn’t need prior training in order to root out an invasive weed in the yard. This is the first line of defense.
Your immune system can also become “acquired” through natural infection or vaccine-induced immunity. Vaccination works by introducing to the body a killed or weakened form of a disease organism, which triggers your immune system to produce antibodies to fight the virus. This type of immunity lasts a long time—often for life.
Some diseases, such as cancer, may make your immune system less robust and may lead to autoimmune disorders, in which the immune system mistakenly attacks the body’s own healthy cells. The best way to prevent these problems is to understand your immune system, what makes it tick, and how everyday things affect its functions.