Abstract
The aim of this study was to observe whether the lysosomal enzymes from human polymorphonuclear leukocytes were capable of destroying periodontal tissue in vivo, when the enzymes were applied into the rabbit gingival sulcus.
Human leukocytes were prepared by sedimentation of heparinized blood. A granule fraction was extracted from homogenate of leukocytes by centrifugation. The granule extract was obtained by freezing and thawing and subsequent centrifugation. A neutral protease of the granule extract was partially purified by a gel chromatography. From the result of biochemical analysis, it was found that the neutral protease fraction exhibited both proteolytic and elastolytic activities. The optimum pH of the neutral protease was approximately 8.3-8.9 with regard to its proteolytic activity. The molecular weight of the enzyme was estimated as 25, 000±3, 000 by a gel chromatography.
All rabbits were given the drinking water containing 0.05% tetracycline hydrochloride for two weeks prior to the experiment to decrease the microorganisms in the crevices. Labial crevices of mandibular incisors of rabbits were used as experimental sites. The strips of filter papar were inserted into those crevices, then the granule extract and the neutral protease were dropped on the filter papar every ten minutes for six hours by tubercline syringe. Saline solution and the heat-inactivated enzymes were used as controls.
Histological findings at experimental sites showed the ulceration of sulcular epithelium and inflammatory exudation in lamina propria. Leukocytic infiltrations into the epithelium were also observed especially at the site where the granule extract was applied. The connective tissue was slightly damaged in the neighborhood of the inflammatory cells at the experimental sites. Inflammatory alterations were hardly found at the three comparable regions of the control sites. The possibility of the direct or indirect destructive effects of lysosomal enzymes on periodontal tissues was indicated by this study.
