Leukotoxicity of an extract from Actinobacillus actinomycetemcomitans for human gingival polymorphonuclear leukocytes.

A soluble extract from Actinobacillus actinomycetemcomitans (designated strain Y4) caused dose-dependent cytotoxic changes in PMN isolated from the gingival crevices (C-PMN) of normal adults. When the toxin was preincubated with sera from patients with juvenile periodontitis, there was a significant inhibition of toxic activity. In contrast a variety of other sera from normal subjects with healthy gingiva, and from patients with chronic gingivitis, chronic periodontitis, recurrent herpes labialis, rheumatoid arthritis, or ulcerative colitis enhanced the leukotoxic activity. The neutralization of toxin by serum from patients with juvenile periodontitis was probably due to specific antibodies. Since Actinobacillus actinomycetemcomitans organisms can be frequently identified in subgingival plaque from patients with juvenile periodontitis, the capacity of Y4 toxin to kill C-PMN may contribute to the pathogenesis of this disease.