IgA

noun

one of the most common of the five major classes of immunoglobulins; the chief antibody in the membranes of the gastrointestinal and respiratory tracts

• Syn: ↑immunoglobulin A

• Hypernyms: ↑immunoglobulin, ↑Ig, ↑immune serum globulin, ↑immune gamma globulin, ↑immune globulin

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\\ˌī(ˌ)jēˈā\ noun

Etymology: Immunoglobulin A

1. : a class of immunoglobulins including antibodies found in external bodily secretions (as saliva, tears, and sweat)

2. : an immunoglobulin of the class IgA

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Immunol.

immunoglobulin A: a class of antibodies predominant in respiratory and alimentary tract secretions and in saliva and tears, functioning as the body's first line of defense against invading foreign substances esp. by neutralizing viral antigens and by preventing the adherence of bacteria to mucous membrane surfaces.

[1960-65]

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IgA (no periods),

immunoglobulin A: »

The immunoglobulin known as IgA…is found only in external secretions (saliva, tears, sweat...) (Lee Edson).