Mucosal immunity in infectious disease and allergy

Abstract

This brief review describes mechanisms for acquired anti-microbial defence in the upper airways originating from active export of secretory immunoglobulin A and IgM, as well as epithelial leakage of serum-derived or locally produced IgG. Evidence is presented for regionalization of mucosal immunity in the upper airways, directed by a preferential profile of adhesion molecules and chemokine receptors expressed on B cells induced in mucosa-associated lymphoid tissue of Waldeyer's ring, especially the palatine tonsils and adenoids, which differs from that imprinted on B cells in gut-associated lymphoid tissue. The possibility is also discussed that allergy is more common in the airways than in the gut because of differences in mucosally induced tolerance mechanisms. The nature of the mucosal epithelium, as well as functional properties of intra- or subepithelial dendritic cells and macrophages, may contribute to less robust local immune tolerance in the respiratory tract.