DEMONSTRATION OF THE IN VITRO PHAGOCYTOSIS OF TREPONEMA DENTICOLA BY HUMAN POLYMORPHONUCLEAR NEUTROPHILS

A method has been developed for the study of phagocytosis of the oral treponeme T. denticola by human polymorphonuclear neutrophils. T. denticola was labelled with 32P-orthophosphate, and phagocytosis, expressed as counts per mg cell protein, was measured after 15, 60 and 120 min of interaction between neutrophils and treponemes. Four different cell cultures were used as controls, and phagocytosis of E. coli was used as reference. The uptake of radiolabelled T. denticola was significantly larger with the PMNs than with any of the control cells. An increase of uptake was observed from 15 to 120 min. The addition of autologous human serum or rabbit T. denticola antiserum enhanced the phagocytosis 2–3 fold, and phagocytosis was decreased under an anaerobic atmosphere. Scanning electron microscopic studies also indicated that phagocytosis had taken place.