Rebecca martin/sandbox2

From Proteopedia

Introduction to IgA

Template:STRUCTURE 1iga The most extensive surface in contact with the external environment is not our skin, but the epithelial lining of our gastrointestinal, respiratory, and urogenital tracts ^[1]. As a first line of defense in maintainance the integrity our mucosa, the immune system manufatures and secretes dimeric IgA to neutralize pathogenic organisms ^[2] and exclude the entry of commensals at the mucosal border ^[3]. In the serum, IgA functions as a second line of defense against pathogens that may breech the epithelial boundary ^[2]. The body produces more IgA than any other antibody isotype ^[3]. In fact, IgA is the most abundant antibody in the body, further illustrating IgA's critical role in immunity ^[4].

Unlike other antibody isotypes, IgA exists in mutiple oligomeric states ^[3]. The most common of which are the monomeric, dimeric, and secretory forms ^[4]. At least two isotypes exist, termed IgA1 and IgA2. IgA2 can further be categorized into 2 allotypes: IgA2 m(1) and IgA2 m(2). The receptors for IgA include the Fcα Receptor (FcαRI; CD89) and the polyimmunologlobulin receptor (pIgRI). When binding to FcαRI results in the dimerization, the consequent signaling results in effector functions, including respiratory burstmucosal surface, an approximately equal ratio of secretory IgA1 (sIgA1) to secretory IgA2 (sIgA2) reside at the mucosal surface, with the exception of the colon, where the majority is sIgA2 ^[5]. In the serum, about 90% of the IgA is monomeric IgA1 ^[4], phaocytosis, and eosinophil degranulation. Binding to the pIgR results in transoocytosis and IgA secretion ^[2]. Exploring IgA's structure and protein interactions illuminates the unique and critical function IgA plays in humoral immunity.