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 part in mucosal immunity and is thereby an important part of the immune system. The next part of this paper will present why some people have IgA deficiency, and the consequences of the body’s IgA levels being too low or non-existing.
- LIVING WITH IGA DEFICIENCY
Selective IgA deficiency is a relatively common condition, the most common one of the primary immunodeficiencies, which occurs generally once in every 400 to 2000 individuals. What causes IgA deficiency is that the B-lymphocytes, cells which normally produce IgA, are unable to mature and become IgA-producing plasma cells. Patients with IgA deficiency seem to be bearing B-cells however these cells are arrested at an immature stage of development and can thereby not produce any IgA. (Jeffry Modell Foundation, 2014). Professor Lennart Hammarström has, with a team of other researchers, determined that IgA deficiency is developed because the patient has a predisposition for IgA deficiency. There is nothing saying for sure that the patient with this exakt set of genes will develop an IgA deficiency, as there are many people with a similar sets of genes who do not get a deficiency, however there is a risk for that patient to develop it. The deficiency has to...