IgA Fc receptors in cattle and horses

The biological role of IgA depends, at least partly, on the interaction with specific receptors (FcαRs) on the surface of leukocytes. The human FcαR, CD89, was the first IgA Fc receptor to be identified, and binding of IgA-coated particles to CD89 triggers numerous cellular effector functions including phagocytosis, antibody-dependent cell-mediated cytotoxicity (ADCC), and release of inflammatory mediators. Recently, CD89 orthologs have been identified in a number of other species, including cows and horses. This brief review will summarize our current knowledge regarding the structure and function of bovine and equine CD89.