Siga wot
On this Wikipedia the language links are at the top of the page across from the article title. Two views, one rotated 90 degrees with respect to the other, of the amino acid chains comprising secretory IgA1. Coordinates of siga wot backbone carbon atom were derived PDB entry 3CHN. Two views, one rotated 90 degrees with respect to the other, of the amino acid chains comprising secretory IgA2.
Coordinates of each backbone carbon atom were derived PDB entry 3cm9. The amount of IgA produced in association with mucosal membranes is greater than all other types of antibody combined. IgA exists in two isotypes, IgA1 and IgA2. They are both heavily glycosylated proteins. IgA1 is the predominant IgA subclass found in serum.
Most lymphoid tissues have a predominance of IgA1-producing cells. In IgA2, the heavy and light chains are not linked with disulfide, but with non-covalent bonds. Both IgA1 and IgA2 have been found in external secretions like colostrum, maternal milk, tears and saliva, where IgA2 is more prominent than in the blood. Polysaccharide antigens tend to induce more IgA2 than protein antigens.
Both IgA1 and IgA2 can be in membrane-bound form. Clearance of IgA is mediated at least in part by asialoglycoprotein receptors, which recognizes galactose-terminating IgA N-glycans. Decreased or absent IgA due to an inherited inability to produce IgA is termed selective IgA deficiency and can produce a clinically significant immunodeficiency. Anti-IgA antibodies, sometimes present in individuals with low or absent IgA, can result in serious anaphylactic reactions when transfused with blood products that incidentally contain IgA. However, most persons with suspected IgA anaphylactic reactions had experienced acute generalized reactions that were from causes other than anti-IgA transfusion. IgA nephropathy is caused by IgA deposits in the kidneys.
It is not yet known why IgA deposits occur in this chronic disease. Some theories suggest an abnormality of the immune system results in these deposits. Celiac disease involves IgA pathology due to the presence of IgA antiendomysial antibodies. HSP occurs usually in small children and involves the skin and connective tissues, scrotum, joints, gastrointestinal tract and kidneys.
Linear IgA bullous dermatosis and IgA pemphigus are two examples of IgA-mediated immunobullous diseases. IgA-mediated immunobullous diseases can often be difficult to treat even with usually effective medications such as rituximab. Vancomycin can induce a linear IgA bullous dermatosis in some patients. Location of secretory component on the Fc edge of dimeric IgA1 reveals insight into the role of secretory IgA1 in mucosal immunity”. The nonplanar secretory IgA2 and near planar secretory IgA1 solution structures rationalize their different mucosal immune responses”. Intestinal IgA synthesis: regulation of front-line body defences”. Let’s go mucosal: communication on slippery ground”.
The functional interactions of commensal bacteria with intestinal secretory IgA”. IgA subclasses in various secretions and in serum”. The immune geography of IgA induction and function”. Alleles and isoforms of human membrane-bound IgA1″.
