Untitled

Abstract

SUMMARYHuman IgA occurs in multiple molecular forms (polymeric and monomcric) and iwo subclasses which show ditferential distribution between the niucosai and circulatory comparimenis of the immune system. However, the molecular form and subclass of specific IgA antibodies are influenced, especially during an immune response, by Ihe type of antigen and duration of the response as well as by the route ofexposure. These considerations quesUon previously held notions thai polymeric IgA and an increased representation of the lgA2 subclass among circulating antibodies or antibodysecreting cells signify their mucosal origin. Although the functional properties of different molecular forms and subclasses of IgA antibodies are incompletely understood, it appears that there is physiological benefit in the diversity of the IgA immune system.