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Immunoglobulins

Test Overview

An immunoglobulins test is done to measure the level of immunoglobulins, also known as antibodiesantibodies, in your blood.

Antibodies are substances made by the body's immune systemimmune system in response to bacteria, viruses, fungus, animal dander, or cancer cells. Antibodies attach to the foreign substances so the immune system can destroy them.

Antibodies are specific to each type of foreign substance. For example, antibodies made in response to a tuberculosistuberculosis infection attach only to tuberculosis bacteria. Antibodies also work in allergic reactions. Occasionally, antibodies may be made against your own tissues. This is called an autoimmune diseaseautoimmune disease.

If your immune system makes low levels of antibodies, you may have a greater chance of developing repeated infections. You can be born with an immune system that makes low levels of antibodies, or your system may make low levels of antibodies in response to certain diseases, such as cancer.

The five major types of antibodies are:

  • IgA. IgA antibodies are found in areas of the body such as the nose, breathing passages, digestive tract, eyes, and vagina. IgA antibodies protect body surfaces that are exposed to outside foreign substances. This type of antibody is also found in saliva, tears, and blood. A small number of people do not make IgA antibodies.
  • IgG. IgG antibodies are found in all body fluids. They are the smallest and most common type of antibody. IgG antibodies are very important in fighting bacterial and viral infections. IgG antibodies are the only type of antibody that can cross the placentaplacenta during pregnancy to help protect the baby (fetus).
  • IgM. IgM antibodies are the largest antibody. They are found in blood and lymph fluid and are the first type of antibody made in response to an infection. They also cause other immune system cells to destroy foreign substances.
  • IgE. IgE antibodies are mostly found in tissue cells, but small amounts are also found in the blood. They cause the body to react against foreign substances such as pollen, fungus spores, and animal dander. They also protect the body from parasite infections. IgE antibody levels are often high in people with allergies.
  • IgD. IgD antibodies are found on the surface of some immune cells in the body. They are uncommon and rarely found in the blood. How they work is not clear.

The levels of each type of antibody can give your doctor information about the cause of a medical problem.

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Current as of: April 30, 2024

Author: Ignite Healthwise, LLC StaffIgnite Healthwise, LLC Staff

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