Vet. Res. 37 (2006) 455-467
DOI: 10.1051/vetres:2006010

The IgA system: a comparison of structure and function in different species

Veerle Snoeck^{a, b}, Iain R. Peters^c and Eric Cox<sup>a

a</sup>  Laboratory of Veterinary Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
^b  Present address: Department of Molecular Biomedical Research, Applied Molecular Bacteriology Unit, Ghent University and V.I.B, Technologiepark 927, 9052 Ghent (Zwijnaarde), Belgium
^c  Division of Veterinary Pathology, Infection and Immunity, School of Clinical Veterinary Science, University of Bristol, Langford House, Langford, Bristol, BS40 5DU, United Kingdom

(Received 19 April 2005; accepted 16 September 2005; published online 23 February 2006)

Abstract - The predominant immunoglobulin isotype on most mucosal surfaces is secretory immunoglobulin A (SIgA), a polypeptide complex comprising two IgA monomers, the connecting J chain, and the secretory component. The molecular stability and strong anti-inflammatory properties make SIgA particularly well suited to provide protective immunity to the vulnerable mucosal surfaces by preventing invasion of inhaled and ingested pathogens. In contrast to SIgA, IgA in serum functions as an inflammatory antibody through interaction with FcR on immune effector cells. Although IgA appears to share common features and protective functions in different species, significant variations exist within the IgA systems of different species. This review will give an overview of the basic concepts underlying mucosal IgA defence which will focus on the variations present among species in structure, antibody repertoire development, pIgR-mediated transport, colostral IgA content, hepatobiliary transport, and function with particular emphasis on the IgA system of the pig and dog. These interspecies variations emphasise the importance of elucidating and analysing the IgA system within the immune system of the species of interest rather than inferring roles from conclusions made in human and mouse studies.

Key words: IgA / polymeric IgR / FcR / mucosal antibodies / domestic animals

Corresponding author: Veerle Snoeck veerle.snoeck@dmbr.UGent.be

© INRA, EDP Sciences 2006