Secretory immunoglobulin A carries oligosaccharide receptors for Escherichia coli type 1 fimbrial lectin.
Type 1 fimbriae with mannose-specific lectins are widely distributed among members of the family Enterobacteriaceae and confer the ability to attach to a range of host cells, including colonic epithelial cells. The mucosal surfaces are protected by secretory immunoglobulin A (IgA), which agglutinates microorganisms and prevents their attachment to host epithelial cells. This action has been attributed to a specificity of the antigen-combining site of mucosal immunoglobulins for bacterial and viral surface components. Here, we report a novel mechanism for the antibacterial effect of secretory IgA. Secretory IgA and IgA myeloma proteins, especially those of the IgA2 subclass, were shown to possess carbohydrate receptors for the mannose-specific lectin of type 1-fimbriated Escherichia coli. The presence of the high-mannose oligosaccharide chain Man alpha 1-6(Man alpha 1-3)Man alpha 1-6(Man alpha 1-3)Man beta 1-4GlcNAc beta 1-4GlcNAc correlated with binding activity. The interaction between bacterial mannose-specific lectins and IgA receptor oligosaccharide resulted in agglutination of the bacteria and in inhibition of bacterial attachment to colonic epithelial cells. Thus, this interaction could form the basis for a broad antibacterial function of secretory IgA against enterobacteria regardless of the specificity of antibody molecules.
Wold
A E
AE
Department of Clinical Immunology, University of Goteborg, Sweden.
Mestecky
J
J
Tomana
M
M
Kobata
A
A
Ohbayashi
H
H
Endo
T
T
Edén
C S
CS
D000371:Agglutination / Q000187:drug effects; D002240:Carbohydrate Sequence; D004926:Escherichia coli / Q000378:metabolism*; D006801:Humans; D007071:Immunoglobulin A, Secretory / Q000378:metabolism*; D037102:Lectins / Q000378:metabolism*; D037181:Lectins, C-Type; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D008969:Molecular Sequence Data; D009194:Myeloma Proteins / Q000494:pharmacology; D011956:Receptors, Cell Surface; D011961:Receptors, Fc; D011971:Receptors, Immunologic / Q000378:metabolism*; D014407:Tumor Cells, Cultured
C045281:IgA receptor; D007071:Immunoglobulin A, Secretory; D037102:Lectins; D037181:Lectins, C-Type; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D009194:Myeloma Proteins; D011956:Receptors, Cell Surface; D011961:Receptors, Fc; D011971:Receptors, Immunologic