IgA antibody, the second most important antibodies in the serum, is responsible for activating the complement pathway and immune system. IgA is a multivalent antibody that is easily identified on the surface of the mucosa. Most of the secreted IgA can be identified on the surface of the mucous membrane, such as the respiratory tract, digestive tract, urogenital tract, and thereby protect the intestine from pathogens while maintaining the homeostasis of the intestine. Meanwhile, recent studies have demonstrated that the lgA can neutralize a number of pathogens by different mechanisms and then trigger defense against various infections.
In general, IgA antibodies are made up of two heavy chains and two light chains. Each chain consists of a constant region, a hinge region as well as a variable region. Furthermore, the total molecular weight of the IgA antibody is about 160 kDa. IgA isotype antibody is prone to be in monomeric form in human serum while in dimeric and secretory forms at the mucosal site. The unique 18-amino acid tail of IgA antibody is a key factor in oligomerization. IgA is comprised of two subtypes, IgA1 and IgA2, and can bind to several receptors, such as FcαRI (CD89), polymeric Ig-receptor (pIgR), asialoglycoprotein, Fcα/μR, as well as transferrin.
Learn more: IgA antibody discovery
