Peroxidase Antimicrobial System ofHumanSaliva: Requirements forAccumulation ofHypothiocyanite

Humansaliva wasfractionated todetermine the components required for production andaccumulationoftheantimicrobial oxidizing agent, hypothiocyanite ion(OSCN-). Therequired components were:1)peroxidase activity andthiocyanate ion(SCN-), 2)thesaliva sediment, whichproducedhydrogen peroxide (H202) inthepresence ofoxygen anda divalent cation, and3)heatstable factors ofthesaliva supernatant. Thesupernatant factors wereseparated intohigh- andlowmolwtfractions. Thehigh-mol wtfraction contained bothpeptide andcarbohydrate, andits activity waspartially inhibited byproteolytic treatment. Thelow-mol wt fraction contained carbohydrate andcouldbereplaced byanumber ofmono-anddi-saccharides. Glucosamine andNacetyl glucosamine werethemosteffective, whereas neutral sugars suchassucrose wereless effective. Sucrosecompeted withglucosamine, sothat lower levels ofOSCN-wereobtained with increasing amountsofsucrose. Thesugars stimulated production ofH202bythesaliva sediment. Production ofH202 wasgreater inthepresence of glucosamine thanofneutral sugars. Also, theratio ofOSCN-accumulation toH202production was greater inthepresence ofglucosamine. Theresults suggest thatperoxidase-mediated antimicrobial activity ismodulated bythecarbohydrate composition ofwholesaliva andbycertain protein and glycoprotein components.