In vaccination a small amount of dead or weakened micro-organisms are injected into the body. They are harmless to ourbut their antigen structure is recognized by the lymphocytes and antibodies are formed. Normally several injections in intervals are required to obtain absolute immunity. These are booster shots. This type of immunity is called artificial active immunity.
Passive natural immunity is the protection from diseases a baby gets from the antibodies of its mother, that pass into itsstream via the placenta. This form of immunity lasts up to the age of approximately six months, when the baby’s own immune system matures and takes over.
The term passive artificial immunity is used when a person is injected with the formed antibodies of another human being. This is done when a person is infected with a rapidly spreading potentially lethal disease, such as tetanus, and there is no time for the patient to develop active natural immunity. Lymphocytes are also involved in allergic reactions. Allergic individuals have plasmawhich produce large amounts of antibodies against common environmental antigens such as grass pollens, animal hair and house dust. Exposure to such allergens causes , hay fever and other allergic reactions including skin . Allergy is an overreaction of the immune system. The function of immunity is to protect us from foreign agents. Normally the immune system reacts only with foreign material. In autoimmunity however the immune system mistakenly identifies its own body or as foreign and reacts with them. A common example of such a disorder is rheumatoid arthritis.
Transplants are readily recognized as foreign material and rejection takes place. In transplantation of the kidney, for example, the immune system must be suppressed using special drugs.