Secretory Component

Secretory component is an ~80kD glycoprotein important in mucosal immunity. Secretory component is the extracellular cleaved ectodomain of the polymeric immunoglobulin (Ig) receptor (pIgR) which transports Igs across mucosal membranes into secretions (reviewed in Johansen, 2011). IgA is the main immunoglobulin in secretions and pIgR is highly expressed in intestinal epithelial cells (ECs). Dimeric IgA (dIgA) manufactured by antibody producing plasma cells in the intestinal lamina propria binds to pIgR at the basolaterial membrane surface of ECs. pIgR-dIgA complexes are internalized and transcytosed across ECs to the apical surface. Secretory component is then proteolytically cleaved off from the pIgR and released into the lumen together with dIgA. Secreted IgA (SIgA) consists of dIgA + secretory component. SIgA protects the mucosa from microbial invasion, and bound Secretory component enhances immune function by inhibiting SIgA proteolytic degradation. Reacts with both free and bound secretory component (Bartek, 1989); it does not react in western blots of cell lines that lack secretory component. The antibody is useful for studying the distribution and level of both free and bound secretory component. \n\nSecretory component is differentially expressed in epithelium, and the antibody is a useful marker for identifying subpopulations of epithelial cells and epithelial differentiation (Fichorova, 1997 & 1998). Secretory component antibodies have also been part of antibody marker panels for differential identification of glandular carcinomas (Brown, 1993; Harris, 1981; Kalhounou, 2010). The Secretory component antibody is a useful research tool for studying mucosal immunity, inflammation, remodeling, differentiation and tumorigenesis, all processes associated with differential secretory component expression (Bartek, 1990; Johansen, 2011). Since the presence of secretory component implies immunological function, the antibody can help identify cells regulating immunological processes (Fichorova, 1999). The antibody can also be used to indirectly assess SIgA expression since SIgA contains bound secretory component (Vancikoa, 2003).\n\nApplications: \nSuitable for use in Immunofluorescence, ELISA, Western Blot, Immunoprecipitation, Immunohistochemistry and Immunocytochemistry. Other applications not tested.\n\nRecommended Dilution:\nImmunohistochemistry: 1:500\nOptimal dilutions to be determined by the researcher.\n\nStorage and Stability:\nMay be stored at 4 degrees C for short-term only. Aliquot to avoid repeated freezing and thawing. Store at -20 degrees C. Aliquots are stable for 12 months. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap.

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