Bacteria-phagocyte interactions: Fusobacterium-induced secretion of a neutrophil self-regulatory factor

Direct interaction between Fusobacterium nucleatum and human neutrophils resulted in the secretion of a neutrophil self-regulatory factor(s). The secretion of this factor was bacteria specific, and depended on the integrity of the bacteria cell surface. Factor secretion occurred within 15 min of bacteria--neutrophil interaction. Pre-treatment of neutrophils with cytochalasin B but not sodium fluoride inhibited factor secretion. The factor was sensitive to trypsin and heat treatment. Ultrafiltration experiments showed that it has a molecular weight between 10,000 and 30,000 daltons. Its biologic role may be that of a molecular mediator for the recruitment of resting neutrophils so as to amplify the immunological and inflammatory response.