In vivo chemotaxis evoked by Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus

The chemotaxis-evoking capacity of 5 Actinobacillus actinomycetemcomitans and 5 Haemophilus aphrophilus strains were studied in a tissue cage model in rabbits. A significant increase of the total number of polymorphonuclear leukocytes was induced in the tissue cage fluid by both viable and killed bacteria, reaching a maximum after 12-24 h. In parallel, the proportion of viable/non viable leukocytes increased. The leukocyte counts declined during the following 24-48 h in all chambers except in those inoculated with viable cells of H. aphrophilus. The H. aphrophilus strains survived the 72 h experiment while A. actinomycetemcomitans decreased to undetectable levels within 24-72 h. Lactate dehydrogenase and lysozyme activities in cage fluid increased in all but the uninoculated chambers. Viable bacteria induced higher activities of the enzymes than killed ones. It is concluded that both species of bacteria exhibit similar chemotaxis evoking properties. A strain dependent ability to induce release of leukocyte-associated enzymes exists.