Library · Molecule
Immunoglobulin A
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Immunoglobulin A, almost always written as IgA, is an antibody: a defense protein. It is the antibody in charge of the mucosa, the moist lining on the inside of the digestive tract, the airways, and the genitourinary tract. It is also the antibody the body produces in the greatest amount.
It follows a curious route to get there. Cells called plasma cells make it one unit at a time, beneath the mucosa, and then two of those units are tied together by a piece called the J chain. To get it across the wall of cells in front of it, a receptor called pIgR picks it up and passes it to the other side, like a doorman who takes a package at the entrance and brings it into the building.
On the way out it keeps a leftover piece of that receptor, the secretory component, which works like a suit of armor: it keeps outside enzymes from breaking it apart. Once outside, IgA sticks to antigens, the parts the body recognizes as foreign, and keeps them from moving down into the tissue and the blood.
Selective IgA deficiency is the most common immunodeficiency in people.
In brief
Immunoglobulin A, or IgA, is the dominant antibody of the digestive, respiratory, and genitourinary mucosa, and the one the body makes in the largest amounts.
It is secreted as single units, joined in pairs by the J chain, and the pIgR receptor carries it across the epithelium.
It comes out with the secretory component, which protects it from being degraded, and there it blocks antigens.
An antibody that steps outside wearing its own armor.
Selective IgA deficiency is the most common immunodeficiency in humans.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingBiochemistry, Immunoglobulin A, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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