Influence of oral bacterial endotoxin on cell migration and phagocytic activity

Abstract

The capacity of endotoxin from oral bacteria to induce inflammation was studied in human subjects by the “skin, window” technique. The inner surface of the forearm was excoriated with a scalpel and sterile cover slips applied to the wounds. Migrating inflammatory cells were found to adhere to the cover slips and regular replacement of the cover slips permitted longitudinal examination of the cytology of the exudates. Topical application of lipopolysaccharide endotoxin from oral Veillonella to the abraded skin areas caused a distinct alteration in the local inflammatory response. An immediate and persistent migration of polymorphonuclear leukocytes occurred, while the appearance of mononuclear cells in the exudates was delayed from 4 to 10 hours depending on the dose of endotoxin. Continued application every second hour of as little as 0.19 μg endotoxin to the lesion extended the phase of polymorphonuclear migration throughout the 14 hour experimental period. Phagocytosis of inert carbon particles was significantly enhanced in lesions treated with endotoxin and followed a characteristic pattern. After a single application of endotoxin an initial peak of phagocytic activity by polymorphonuclear leukocytes was observed 4 to 6 hours later. A second peak at 12 hours was caused by the phagocytic action of mononuclear cells. The role of oral bacterial endotoxin in gingival inflammation is discussed in the light of these results.