Which antibody best protects mucosal surfaces?

Which antibody best protects mucosal surfaces?

• A. IgG
• B. IgD
• C. IgM
• D. IgA

Answer: (D)

Secretory IgA provides the main line of defense at mucosal surfaces. It is produced as a dimer by plasma cells in mucosa-associated lymphoid tissue and crosses the epithelium, acquiring a secretory component that protects it from mucus proteases. In the lumen, secretory IgA neutralizes pathogens and toxins and prevents their attachment to epithelial cells, a strategy known as immune exclusion. This mode of action aims to keep pathogens out of the body while minimizing inflammatory damage to delicate mucosal tissues. Other antibodies contribute to systemic defense or have different roles, but secretory IgA is specialized for constant protection where mucosal barriers are routinely exposed to microbes.

Secretory IgA provides the main line of defense at mucosal surfaces. It is produced as a dimer by plasma cells in mucosa-associated lymphoid tissue and crosses the epithelium, acquiring a secretory component that protects it from mucus proteases. In the lumen, secretory IgA neutralizes pathogens and toxins and prevents their attachment to epithelial cells, a strategy known as immune exclusion. This mode of action aims to keep pathogens out of the body while minimizing inflammatory damage to delicate mucosal tissues. Other antibodies contribute to systemic defense or have different roles, but secretory IgA is specialized for constant protection where mucosal barriers are routinely exposed to microbes.