Identification of a nonlysozymal bactericidal factor (beta lysin) in human tears and aqueous humor.

An antibacterial factor, identical with or closely related to beta lysin, was measured in human tears, in human aqueous humor, and in fractions of each fluid after an absorption step involving cellulose-asbestos filters. Antibeta lysin was used to help distinguish whether bactericidal activity was due to lysozyme or beta lysin. Beta lysin activity was found in both human tears and aqueous humor in higher amounts than were present in serum; appreciable amounts of lysozyme were found in human tears but not in aqueous humor. Beta lysin is a normal constituent of human tears and aqueous humor and its role in these fluids is that of an antibacterial agent that may also act in concert with lysozyme to destroy bacteria in tears.