Antibodies, or immunoglobulins, are Y-shaped proteins that are used to identify pathogens in your body for destruction by your white blood cells and immune system. Antibodies are made by your B cells come in a variety of types:
- IgA – can be found in your gut, tears, saliva, and lung.
- IgD – found on the surface of immature B-cells. Can activate other white blood cells.
- IgE –referred to as the allergic antibody because it binds to allergens and causes histamine release.
- IgG – Majority of the antibodies in your body. Can cross the placenta to give immunity to the fetus.
- IgM – Also expressed on the surface of B cells. Also found in the blood as a collection of 5 grouped together forming a pentamer.
Antibodies work by binding to a molecule called an antigen. Antigens are usually proteins but can also be carbohydrates or lipids (less frequently). Antibodies recognize and attach to a very specific region on the antigen called the epitope. Your body has a remarkable ability to make a large variety of antibodies to almost any molecule imaginable. Each antibody is specific to only one protein or antigen, like a key to a lock.
Antibodies are used to identify viral, bacterial, or parasitic antigens. To make sure antibodies only recognized foreign invaders, your body educates B-cells by showing them all the proteins your body makes. If a certain antibody recognizes one of your body’s own proteins, it is destroyed so it cannot cause damage. Unfortunately, this system is not perfect and some B-cells may escape this training and produce antibodies that can attack your body. This is called autoimmunity and causes diseases like Lupus.
Antibodies are also very useful in science for identifying specific proteins or in medicine for getting rid of harmful proteins or cancer.
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