title: Pulmonary clearance and phagocytic cell response to normal pharyngeal flora.
abstract: Because human lungs are repetitively inoculated with the normal bacterial flora of the pharynx, we determined the pulmonary clearance of representative species after aerosol inoculation of a murine model, and characterized the phagocytic cell response by bronchoalveolar lavage. Viable bacteria remaining in the lungs at 1, 2, and 4 h were: Streptococcus sanguis, 24%, 8%, and 1%; Streptococcus salivarius, 49%, 24%, and 5%; Neisseria catarrhalis, 69%, 49%, and 22%. Clearance of Streptococcus sanguis was associated with a twofold increase in alveolar macrophages (p less than 0.05); Streptococcus salivarius evoked a doubling of alveolar macrophages and a 20-fold rise in granulocytes (p less than 0.05); the response to Neisseria catarrhalis was a 400-fold increase in granulocytes (p less than 0.05). Thus, normal pharyngeal organisms are cleared rapidly from the lung by a dual phagocytic cell system. It is speculated that bacteria-phagocyte interaction allows the possibility of lung injury from proteolytic enzymes released from either set of phagocytes.
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology; D005260:Female; D008168:Lung / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D009343:Neisseria; D010586:Phagocytes / Q000502:physiology*; D010614:Pharynx / Q000382:microbiology*; D013291:Streptococcus; D013298:Streptococcus sanguis
chemical_list: D000907:Antibodies, Bacterial