EFFECT OF ORAL BACTERIA ON PERIPHERAL-BLOOD LEUKOCYTE INTERLEUKIN-6 AND SOLUBLE INTERLEUKIN-6 RECEPTOR PRODUCTION

To determine the effect of pathogenic oral bacteria on interleukin 6 ( IL-6) and soluble IL-6 receptor production, we measured their release by human peripheral blood mononuclear cells in vitro. Unseparated peri pheral blood mononuclear cells, peripheral blood lymphocytes (monocyte depleted), pure T cells, or monocytes were cultured with Actinobacill us actinomycetemcomitans, Capnocytophaga gingivalis, Capnocytophaga oc hracea, Fusobacterium nucleatum or Porphyromonas gingivalis for 24 h. Supernatants were tested for IL-6 and soluble IL-6 receptor by enzyme- linked immunosorbent assay. Only monocytes and peripheral blood mononu clear cells responded with significant IL-6 release in the presence of all bacteria tested. However, peripheral blood lymphocytes were capab le of producing IL-6 when activated by phytohemagglutinin or IL-2 foll owed by bacteria, though substantially less than cultures containing m onocytes. No bacteria tested increased soluble IL-6 receptor release o ver spontaneous soluble IL-6 receptor release. We conclude that monocy tes release IL-6 after contact with oral pathogens; however, soluble I L-6 receptor from T cells and monocytes is constitutively produced and may modulate IL-6 actions.