The Immune System and IgA Deficiency

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THE IMMUNE SYSTEM AND IGA DEFICIENCY - IGA’S FUNCTION IN THE BODY Immunoglobulin A, or IgA, is an antibody which is produced in mucosal linings and plays an important part in mucosal immunity. In the mucosal linings, more IgA is produced than all other types of antibodies combined. The amount of produced IgA contributes greatly to the total immunoglobulin production and around three to five grams of IgA are secreted into the intestinal lumen every day. IgA is divided into two subclasses, IgA 1 and IgA 2 and can also exist in a dimeric form called secretory IgA, sIgA. IgA1 is the predominant subclass which is found in serum. Most lymphoid tissues have a predominance of cells which produce IgA. The share of IgA2 production is larger in secretory lymphoid tissues than in the non-secretory lymphoid organs (spleen, peripheral lymph nodes, etc.). In IgA2, the heavy and light chains are linked with non-covalent bonds instead of with disulphide. The secretory form of IgA, sIgA, is the main immunoglobulin found in mucous secretions such as colostrum and secretions from the genitourinary tract, gastrointestinal tract, prostate and respiratory epithelium, tears and saliva (which is important when testing IgA levels for IgA deficiency which will be discussed later in this paper) and also in small amounts of blood. The secretory component of sIgA protects the immunoglobulin from being degraded by certain enzymes and makes sIgA able to survive in the harsh environment of the gastrointestinal tract and thereby provide protection against microbes which multiply in body secretions. Secretory IgA can also inhibit inflammatory effects of other immunoglobulins (National library of medicine, 2011). As stated above, IgA plays a critical... ... middle of paper ... ...Patient and Family Handbook for Primary Immunodeficiency Diseases - Selective IgA deficiency. 5th ed. Maryland, USA. Izenberg, Neil MD. 2011. Kids health, Immune system. [ONLINE] Available at: http://kidshealth.org/parent/general/body_basics/immune.html#. [Accessed 04 March 14]. Jeffry Modell Foundation, Primary immunodeficiency resource center. 2013. Primary immunodeficiency diseases - Selective IgA deficiency. [ONLINE] Available at: http://kidshealth.org/parent/general/body_basics/immune.html#. [Accessed 02 March 14]. National Library of Medicine - Medical Subject Headings. 2011. Immunoglobulin A. [ONLINE] Available at: http://www.nlm.nih.gov/cgi/mesh/2011/MB_cgi?mode=&term=Immunoglobulin+A. [Accessed 24 April 14]. Worldbook. 2014. Fibroblast search. [ONLINE] Available at: http://worldbookonline.com/advanced/dict?lu=fibroblast. [Accessed 26 April 14].

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