Which immunoglobulin class has a secretory component and is found in saliva, tears, and body secretions?

Which immunoglobulin class has a secretory component and is found in saliva, tears, and body secretions?

• A. IgA
• B. IgD
• C. IgG
• D. IgM

Answer: (A)

Secretory IgA is the antibody class specialized for mucosal surfaces. It is produced as a dimer with a J chain in mucosa-associated lymphoid tissue, then binds to the polymeric Ig receptor on epithelial cells and is transported into secretions. The part of the receptor that remains attached, the secretory component, protects the IgA from proteolysis in harsh environments like saliva and tears. This secretory IgA can then neutralize microbes and toxins right at the entry points, providing immune protection where many pathogens first contact the body. That’s why saliva, tears, and other body secretions are rich in this antibody.

Secretory IgA is the antibody class specialized for mucosal surfaces. It is produced as a dimer with a J chain in mucosa-associated lymphoid tissue, then binds to the polymeric Ig receptor on epithelial cells and is transported into secretions. The part of the receptor that remains attached, the secretory component, protects the IgA from proteolysis in harsh environments like saliva and tears. This secretory IgA can then neutralize microbes and toxins right at the entry points, providing immune protection where many pathogens first contact the body. That’s why saliva, tears, and other body secretions are rich in this antibody.