Cytopathic effects of Actinobacillus actinomycetemcomitans on monkey blood leukocytes

The suitability of cynomolgus monkeys (Macaca fascicularis) for studies concerned with the biologic properties of Actinobacillus actinomycetemcomitans is the subject of the present investigation. We found that normal monkeys harbored leukotoxic strains of A. actinomycetemcomitans in subgingival plaque samples. Monkey peripheral blood PMNs and monocytes were killed following in vitro exposure to sonic extracts of leukotoxic strains of A. actinomycetemcomitans. Monkey sera were capable of inhibiting the leukotoxic properties of A. actinomycetemcomitans sonic extracts due to the presence of IgG antibodies which neutralized the leukotoxin. Similarly, sera from patients with juvenile periodontitis (but not normal human sera) abolished leukotoxin-mediated killing of monkey PMNs. Monkey peripheral blood lymphoid cells were not killed by A. actinomycetemcomitans but demonstrated depressed responses to mitogens following pre-incubation with A. actinomycetemcomitans sonicates prepared from either leukotoxic or “non-leukotoxic” human strains. These studies suggest that cynomolgus monkeys may serve as a suitable in vitro and in vivo model for delineating more about host-A. actinomycetemcomitans interrelationships in the etiology of human periodontal disease.