Leukotoxic effects of Actinobacillus actinomycetemcomitans

Abstract

A sonic extract of Actinobarillus actinomycetemcomitans Y4, a microorganism originally isolated from a patient with juvenile periodontitis, contains a leukotoxin (Aa‐leukotoxin) which specifically kills human polymorphonuclear leukocytes (PMNs) and monocytes. In the presence of normal human sera, the toxicity of the leukotoxin is enhanced, whereas sera from patients with juvenile periodontitis neutralize leukotoxic activity. In juvenile penodontitis serum immunoglobulin G was identified as the specific inhibitor of the Aaleukotoxin. The leukotoxin enhancing factor(s) in normal human serum appeared to be a large molecular weight protein which was not immunoglobulin. Pooled sera from rabbits immunized with A. actinomycetemcomitans Y4 sonic extract also neutralized Aaleukotoxic activity while normal rabbit serum enhanced toxicity. The presence of antileukotoxin antibody in sera from individuals with juvenile periodontilis suggests that these people have been immunized with A. actittotnyCetemeomitans microorganisms. Monitoring of this antibody may be a convenient tool in the study of the etiology of juvenile periodontitis.