BioAcyl Corp

 The common mucosal immune system, illustrating the origin of antigen-stimulated, IgA-committed B cells and cognate T cells in inductive sites, mainly the organized mucosa-associated lymphoid tissues of the respiratory and intestinal tracts, i.e., the palatine, tubal, and lingual tonsils and adenoids, and the gut-associated lymphoid tissues (GALT) i.e., small intestinal Peyer’s patches and large intestinal follicles, respectively. Note that bronchus-associated lymphoid tissue (BALT) does not usually occur in healthy adults, but can be found in children, or be induced by infection (52). Antigen-stimulated B and T cells emigrate and traffic through mesenteric lymph nodes into the circulation, and ultimately home into the lamina propria of respiratory, intestinal, and genital tracts and stroma of salivary, lacrimal, and lactating mammary glands, etc. Homing of cells into mucosal effector sites is orchestrated by the expression of vascular endothelial addressins and production of chemokine ligands in mucosal effector sites, and corresponding integrins and chemokine receptors expressed on B and T cells induced in mucosal inductive sites. Terminal differentiation of B cells into pIgA-secreting plasma cells occurs in these effector sites with help from T cells and locally produced cytokines. SIgA is formed by the pIgR-mediated epithelial transport of this locally synthesized pIgA into the secretions, the extracellular part of pIgR becoming the secretory component of SIgA.