Biological qualities of saliva sterilized by filtration or ethylene oxide treatment

Abstract

Stimulated whole saliva was centrifuged and sterilized either by filtration in the presence or absence of dithiothreitol (DTT) or by ethylene oxide treatment. Filtration was accomplished by 2 different techniques: conventional positive pressure filtration through prefilters and membranes with decreasing pore sizes and tangential flow microporous filtration. The sterile saliva samples were analyzed for enzyme activities of phosphatases, esterases, glucuronidase, and lysozyme. The samples were also tested by polyacrylamide electrophoresis, isoelectric focusing and for IgA concentration. Moreover, the samples were tested for support of bacterial growth of strains from the genera Actinomyces, Lactobacillus, Neisseria, Rothia and Streptococcus after the addition of glucose at a final concentration of 0.5%. The samples treated with ethylene oxide appeared to be more affected by this treatment than samples treated otherwise, as demonstrated by the electrophoretic analyses and analyses of enzyme activities. Ethylene oxide-treated saliva also was the least favorable saliva sample to support growth of bacteria. The positive pressure technique gave more rapid filtration than the tangential flow technique. DTT treatment of saliva facilitated filtration and, in contrast to ethylene oxide treatment, it affected the qualities of saliva only to a minor extent compared with the original saliva sample.