Definition

1. Noun:
   • A specific class of antibody: Immunoglobulin A is one of the five primary classes of antibodies (immunoglobulins) found in the immune system. It is the predominant antibody present in the mucous membranes lining the gastrointestinal and respiratory tracts, as well as in secretions like saliva, tears, and breast milk, serving as a first line of defense against pathogens.

Usage Examples

• Noun:
  • Secretory immunoglobulin A provides crucial protection against infections at mucosal surfaces.
  • A deficiency in immunoglobulin A is one of the most common immune system disorders.
  • The study measured the levels of immunoglobulin A in the participants' saliva.

Advanced Usage

• "Secretory immunoglobulin A (sIgA)": This refers to the specific, dimeric form of IgA that is actively transported across mucosal epithelia into secretions, where it performs its primary protective function.
  • Secretory immunoglobulin A is stabilized by a secretory component that protects it from enzymatic degradation.

Variants and Related Words

• IgA (n): The standard abbreviation for immunoglobulin A.
  • The lab report showed elevated serum IgA levels.
• Immunoglobulin (n): The general term for all antibody classes, including IgA, IgG, IgM, IgD, and IgE.
  • Each immunoglobulin class has a distinct structure and function.

Synonyms

• Antibody A: A less common synonym emphasizing its identity as an antibody.
• Mucosal antibody: A descriptive term highlighting its primary site of action.

Related Phrases

• Immunoglobulin A deficiency: A medical condition characterized by low or absent levels of IgA in the blood and secretions.
  • Individuals with immunoglobulin A deficiency may be more susceptible to respiratory and gastrointestinal infections.
• Immunoglobulin A nephropathy: A kidney disease (Berger's disease) characterized by deposits of IgA in the glomeruli.
  • The biopsy confirmed a diagnosis of immunoglobulin A nephropathy.

Noun

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