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.