Micro & Immunology · single question
What is the PRIMARY antimicrobial function of secretory IgA (sIgA) in saliva?
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Correct answer: A. Prevention of bacterial adhesion to mucosal surfaces
Secretory IgA prevents bacterial adhesion to mucosal surfaces (immune exclusion) — it does not destroy bacteria directly.
- A. CORRECT. sIgA binds microbial antigens and prevents bacteria from adhering to mucosal epithelium — a process called 'immune exclusion.' This is its primary antimicrobial mechanism in saliva.
- B. Complement activation via the classical pathway is primarily mediated by IgM and IgG, not IgA.
- C. Neutralization of LPS (endotoxins) is not the primary role of sIgA.
- D. Opsonization is primarily mediated by IgG and IgM, not IgA.
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