Immunoglobulin a

Immunoglobulin A (IgA) is an antibody that plays a crucial role in the immune system's function in the mucous membranes. The amount of IgA produced in association with mucosal membranes is greater than all other types of antibody combined. In absolute terms, between three and five grams are secreted into the intestinal lumen each day. This represents up to 15% of total immunoglobulins produced throughout the body.

Structure

IgA has two subclasses (IgA1 and IgA2) and can be produced as a monomeric as well as a dimeric form. The IgA dimeric form is the most prevalent and is also called secretory IgA (sIgA).

Function

IgA has a key role in preventing infections and controlling the immune response to potential infection. It does this by preventing the attachment of viruses and bacteria to epithelial cells.

Clinical significance

IgA deficiency is a common primary immunodeficiency where the body produces insufficient IgA. It can result in increased rates of respiratory infections, allergy, autoimmune disease, and inflammatory bowel disease.

See also

• Immunoglobulin
• Antibody
• Immune system
• Mucous membrane

References

Immunoglobulin a Resources
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