pIgRmediated

pIgRmediated refers to a biological process involving the polymeric immunoglobulin receptor (pIgR). The pIgR is a transmembrane protein primarily found on the basolateral surface of epithelial cells that line various mucosal surfaces, such as the gut, airways, and reproductive tract. Its main function is to transport dimeric immunoglobulin A (IgA) and pentameric immunoglobulin M (IgM) from the bloodstream and tissue fluids across these epithelial cells into mucosal secretions. This process is crucial for providing humoral immunity at these important interfaces with the external environment.

The pIgR binds to the Fc region of dimeric IgA or pentameric IgM on the basolateral side. This receptor-ligand complex is then endocytosed and transported in vesicles through the epithelial cell. As these vesicles move towards the apical surface, the pIgR undergoes proteolytic cleavage. This cleavage releases the immunoglobulin complex, now attached to a fragment of the pIgR known as the secretory component, into the lumen of the mucosal surface. This secreted complex is referred to as secretory IgA (sIgA) or secretory IgM (sIgM). Secretory component helps to stabilize the immunoglobulins in the harsh environment of mucosal secretions and also prevents their non-specific binding to the epithelium.

pIgRmediated transport is therefore a vital mechanism for establishing mucosal immunity, offering protection against a wide range of pathogens and foreign antigens. Disruptions in this process can have significant implications for immune defense at mucosal surfaces.