April Shields, age 13, of Akron, Ohio, for her question:
HOW DO ANTIBODIES WORK?
An antibody is a protein that is naturally existing in human blood serum or is produced in response to stimulation by an antigen that reacts to overcome the toxicity of a specific antigen. It is part of the body's immunity system.
When a harmful organism called an immunogen or an antigen enters the body, specialized cells in the body react. Some of these cells attack the immunogen directly in a process called cell mediated immunity. Others manufacture special proteins that are released into the blood. These proteins are called antibodies and they neutralize or destroy the immunogen. This type of defense is called humoral immunity.
Antibodies defend the body in several ways. Some dissolve bacteria. Others change the surface of immunogens so that the immunogens clump together. The clumps are easily found by macrophages, which digest them. Macrophages are groups of cells that have an important role in immune responses.
Still other antibodies attach themselves to, and then cover, viruses or poisonous proteins, destroying the effect of the virus or poison.
Most antibodies are highly specific. This means they act effectively against only one kind of immunogen. The antibody that fights one strain of virus is not effective against another.
In some cases, when immunogens enter the body, the body produces enough antibodies to prevent symptoms from developing. In other cases, the body does not produce enough antibodies to prevent symptoms of disease or poisoning. However, the antibodies may help the victim recover.
Every person is naturally resistant to many diseases. The body does not provide the necessary nutrients or the proper temperature for some disease producing organisms that infect plants or other animals.
Active immunity results from having a certain immunogen in the body.
The term immune response or immune reaction refers to the body's production of disease fighting cells and antibodies. Scientists who study this process are called immunologists. Any medical procedure that enables a person to develop immunity to a specific disease producing organism is called immunization.
In addition to disease producing organisms, many other substances also produce an immune reaction. For example, poisons from various kinds of insects, spiders and snakes are immunogens.
Some immune reactions themselves produce diseases. In some persons, pollens cause antibody production that results in an allergy.
Many drugs and serums stimulate the production of antibodies. Such antibody production may result in serum sickness. In addition, organs transplanted from another person trigger the body's immune defenses. One of the chief problems in tissue transplants involves overcoming such an unwanted response.
In rare cases, a person's body may produce antibodies that attack the individual's own tissues, resulting in a condition called autoimmunity.