Basement Membrane Modulation of Stimulated Secretion by Lacrimal Acinar Cells

Lacrimal acinar cells rest basally on a basement membrane and have a secretory granule-filled apical cytoplasm adjacent to a lumen into which tear proteins are released. An important array of proteins are produced. In man, tear proteins are estimated to number as many as sixty (Gachon et al, 1979) and include: lysozyme, which plays a prominent bacteriocidal role on the corneal surface; lactoferrin, which functions as both a bacteriocidal agent and as a potential inhibitor of complement activation; secretory component, which regulates the transcellular movement of IgA into acini lumen where it acts on the corneal surface to inhibit bacterial adhesion; tear-specific prealbumin, whose function is not known. In rats, peroxidase is a tear component which has served as a convenient marker in experimental studies. Tears not only have an important bacteriocidal role, they also keep the cornea clean and lubricated, and are important for the well-being of the corneal epithelium.