Everything about Immunisation totally explained
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For financial immunization, see Immunization (finance).
Immunization, or
immunisation, is the process by which an individual's
immune system becomes fortified against an agent (known as the
immunogen).
When the human immune system is exposed to
molecules that are foreign to the body (
non-self), it'll orchestrate an immune response, but it can also develop the ability to quickly respond to a subsequent encounter (through immunological memory). This is a function of the
adaptive immune system. Therefore, by exposing an individual to an immunogen in a controlled way, their body can learn to protect itself: this is called active immunization.
The most important elements of the immune system that are improved by immunization are the
B cells (and the
antibodies they produce) and
T cells.
Memory B cell and
memory T cells are responsible for a swift response to a second encounter with a foreign molecule. Passive immunization is when these elements are introduced directly into the body, instead of when the body itself has to make these elements.
Immunization can be done through various techniques, most commonly
vaccination. Vaccines against
microorganisms that cause
diseases can prepare the body's immune system, thus helping to fight or prevent an
infection. The fact that
mutations can cause
cancer cells to produce proteins or other molecules that are unknown to the body forms the theoretical basis for therapeutic
cancer vaccines. Other molecules can be used for immunisation as well, for example in experimental vaccines against
nicotine (
NicVAX) or the hormone
ghrelin (in experiments to create an obesity vaccine).
Passive and active immunization
Immunization can be achieved in an active or passive fashion: vaccination is an active form of immunization.
Active immunization
» Main article: Active immunity
Active immunization is where a foreign molecule is introduced into the body and the body itself generates the immunity against the target. This immunity comes from the T cells and the B cells with their antibodies.
Active immunization can occur naturally when a person comes in contact with, for example, a microbe. If the person hasn't yet come into contact with the
microbe and has no pre-made antibodies for defense (like in passive immunization), the person can become immunized. The immune system will eventually create antibodies and other defenses against the microbe. The next time, the immune response against this microbe can be very efficient; this is the case in many of the childhood infections that a person only contracts once, but then is immune.
Artificial active immunization is where the microbe, or parts of it, are injected into the person before they're able to take it in naturally. If whole microbes are used, they're pre-treated, so that they won't harm the injected person as the naturally occurring microbe would. Depending on the type of disease, this technique also works with dead microbes, parts of the microbe, or treated
toxins from the microbe.
Passive immunization
» Main article: Passive immunity
Passive immunization is where pre-made elements of the immune system are transferred to a person, and the body doesn't have to create these elements itself. Currently,
antibodies can be used for passive immunization. This method of immunization begins to work very quickly, but it's short lasting, because the antibodies are naturally broken down, and if there are no B cells to produce more antibodies, that'll disappear.
Passive immunization can be naturally acquired when
antibodies are being transferred from mother to
fetus during
pregnancy, to help protect the fetus before and shortly after birth.
Artificial passive immunization is normally given by
injection and is used if there has been a recent outbreak of a particular disease or as an emergency treatment to poisons (for example, for
tetanus). The antibodies can be produced in animals or
in vitro.
Further Information
Get more info on 'Immunisation'.
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