Secretory immunoglobulin A: well beyond immune exclusion at mucosal surfaces

Immunopharmacol Immunotoxicol. 2009 Jun;31(2):174-9. doi: 10.1080/08923970802438441.


At mucosal surfaces, secretory IgA (SIgA) antibodies serve as the first line of defense against microorganisms through a mechanism called immune exclusion that prevents interaction of neutralized antigens with the epithelium. In addition, SIgA plays a role in the immune balance of the epithelial barrier through selective adhesion to M cells in intestinal Peyer's patches. This mediates the transepithelial retro-transport of the antibody and associated antigens from the intestinal lumen to underlying gut-associated organized lymphoid tissue. In Peyer's patches, SIgA-based immune complexes are internalized by underlying antigen-presenting cells, leaving the antigen with masked epitopes, a form that limits the risk of overwhelming the local immune protection system with danger signals. This translates into the onset of mucosal and systemic responses associated with production of anti-inflammatory cytokines and limited activation of antigen-presenting cells. In the gastrointestinal tract, SIgA exhibits thus properties of a neutralizing agent (immune exclusion) and of an immunopotentiator inducing effector immune responses in a noninflammatory context favorable to preserve local homeostasis.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Antigen-Presenting Cells / immunology
  • Antigens / immunology
  • Cytokines / immunology
  • Gastrointestinal Tract / immunology
  • Immunoglobulin A, Secretory / immunology*
  • Intestinal Mucosa / immunology*
  • Mice
  • Peyer's Patches / immunology


  • Antigens
  • Cytokines
  • Immunoglobulin A, Secretory