What is the main function of SIgA?

Through a process known as immune exclusion, SIgA promotes the clearance of antigens and pathogenic microorganisms from the intestinal lumen by blocking their access to epithelial receptors, entrapping them in mucus, and facilitating their removal by peristaltic and mucociliary activities.

How is SIgA produced?

(1) SIgA is not synthesized by mucosal epithelial cells in these structures or derived from blood. Instead, it is produced by B-lymphocytes adjacent to the mucosal cells, then transported through the cell interiors, and released into the secretions from the cells.

Why is IgA important?

Immunoglobulin A (IgA), as the principal antibody class in the secretions that bathe these mucosal surfaces, acts as an important first line of defence. IgA, also an important serum immunoglobulin, mediates a variety of protective functions through interaction with specific receptors and immune mediators.

Is IgM a secretory antibody?

IgM is the first antibody secreted by the adaptive immune system in response to a foreign antigen. Monomeric IgM is a heterotetramer of approximately 180 kDa. However, the secreted form of IgM exists predominantly in a pentameric configuration with a molecular weight greater than 900 kDa.

Where does the term secretory immunity come from?

Medium electron dense secretory granules first appeared in the acinar cells of parotid gland at 30 cm CVRL (141st day). The term ” secretory immunity” refers to production of specialized antibodies like IgA in the mucous membranes lining the nose, and portions of the windpipe and lungs.

What’s the difference between serum and secretory IgA?

Serum vs. secretory IgA. It is also possible to distinguish forms of IgA based upon their location – serum IgA vs. secretory IgA. In secretory IgA, the form found in secretions, polymers of 2-4 IgA monomers are linked by two additional chains; as such, the molecular weight of slgA is 385,000D.

Where is the secretory dimer of immunoglobulin produced?

Polymeric IgA (mainly the secretory dimer) is produced by plasma cells in the lamina propria adjacent to mucosal surfaces. It binds to the polymeric immunoglobulin receptor on the basolateral surface of epithelial cells, and is taken up into the cell via endocytosis.

What are the different types of immunity in the body?

Immunity Types. Antibodies are proteins produced by the body to neutralize or destroy toxins or disease-carrying organisms. Antibodies are disease-specific. For example, measles antibody will protect a person who is exposed to measles disease, but will have no effect if he or she is exposed to mumps.