IgA stands for Immunoglobulin A, an antibody blood protein crucial for the immune system.
IgA is one of the major classes of immunoglobulins (antibodies) produced by the body to protect against infections. It plays a vital role in neutralizing pathogens, primarily in mucosal areas. Here's a more detailed breakdown:
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Function: IgA's main function is to prevent pathogens (like bacteria and viruses) from attaching to and penetrating mucous membranes, such as those lining the respiratory tract, gastrointestinal tract, and genitourinary tract. It also helps to neutralize toxins and prevent their absorption.
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Location: IgA is found in high concentrations in mucosal secretions such as:
- Tears
- Saliva
- Colostrum (early breast milk)
- Intestinal fluids
- Respiratory secretions
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Structure: IgA exists in two main forms:
- Monomeric IgA: Found primarily in the blood.
- Dimeric IgA: Found in mucosal secretions; consists of two IgA monomers joined together with a "J chain" and a "secretory component." The secretory component protects IgA from being degraded by enzymes in the mucosal environment.
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Clinical Significance:
- IgA Deficiency: The most common primary immunodeficiency, characterized by low levels or absence of IgA in the blood. Individuals with IgA deficiency may be more susceptible to infections, allergies, and autoimmune diseases.
- IgA Nephropathy (Berger's disease): A kidney disease caused by the deposition of IgA in the glomeruli (filtering units of the kidneys).
In summary, Immunoglobulin A (IgA) is a critical antibody that helps protect the body against infection, particularly in mucosal areas, representing a vital component of the immune response.
