The role of Fc–FcγR interactions in IgG-mediated microbial neutralization

Antibodies are bifunctional molecules, containing a variable Fab domain that mediates binding specificity and a constant Fc domain that bridges antibody-coated targets with FcγR-expressing cells that mediate effector functions. Although traditional mechanisms of antibody-mediated neutralization of microbes have been largely thought to result from Fab-antigen interactions, recent studies suggest that recruitment of FcγR-expressing effector cells by antibodies is a major in vivo mechanism of antibody-mediated protection from infection. In this article, we review FcγR biology, compare mammalian FcγR families, and summarize recent evidence demonstrating the crucial role that Fc-FcγR interactions play during in vivo protection from infection.