sIgA is produced by plasma cells located in the lamina propria of mucosal tissues. These plasma cells release dimeric IgA, which binds to the polymeric immunoglobulin receptor (pIgR) on the basolateral surface of epithelial cells. The complex is then transported across the epithelial cell and released into the lumen, where the secretory component is cleaved, forming the complete sIgA molecule.
