Immunoglobulin A: Molecular mechanisms of function and role in immune defence

Our immune system produces more immunoglobulin A (IgA) than all of the other antibody classes combined. Much of this synthesis is directed towards protection of the mucosal surfaces which form a vast and vulnerable interface with the environment. As the predominant immunoglobulin class at these surfaces, IgA is an important first line of defence. In addition, IgA is also a major serum immunoglobulin. Both monomeric IgA in serum and polymeric secretory forms of IgA mediate a wide range of protective functions through interaction with numerous receptors and other mediators. It is telling that in order to gain better opportunities for invasion, certain pathogens have evolved mechanisms to thwart IgA function. An improved understanding of this multifaceted immunoglobulin is likely to inform strategies for improved treatments for infections and other diseases.