Chewing stimulates secretion of human salivary secretory immunoglobulin A

Immunoglobulin A (IgA) is the most abundant immunoglobulin in saliva and other mucosal secretions and plays an important role in mucosal immunity. The present study examined whether secretion of IgA, like other salivary proteins, is increased by reflex stimulation. Parotid saliva was collected from subjects into separate vials under resting conditions and during chewing-stimulated secretion over 45 min. Enzyme-linked immunosorbent assay (ELISA) indicated that chewing increased IgA secretion. The extent and pattern of the increase were similar to those of total protein and acinar cell amylase. SDS gel electrophoresis and Western blotting showed that high-molecular-weight forms of IgA-containing secretory component predominated in all saliva samples. Secretory component, the cleaved epithelial receptor for polymeric IgA, was secreted in a pattern very similar to that of IgA. It is concluded that chewing stimulates epithelial cell transcytosis of IgA and increases secretion of secretory IgA into saliva.