title: Toxicity of Haemophilus pleuropneumoniae to porcine lung macrophages.
abstract: Viable Haemophilus pleuropneumoniae bacteria were toxic for porcine alveolar macrophages in vitro. This cytotoxic effect proved to be dose-related. A cell-free extract of H. pleuropneumoniae, heat-killed bacteria, and a Pasteurella multocida field strain were nontoxic. When macrophages were cultured with H. pleuropneumoniae bacteria in a ratio of 100 macrophages to six bacteria, ultrastructural signs of cellular degeneration were observed within 1 h. This degeneration was observed in macrophages with or without phagosomes containing H. pleuropneumoniae. A cytotoxic substance was filtered from a H. pleuropneumoniae culture in Eagle's minimal essential medium supplemented with Earle's salts (EMEM) and 10% foetal calf serum that was incubated for 10 h at 37 degrees C. This substance was destroyed by heating at 65 degrees C for 30 min. Macrophages were less susceptible to the toxic effect of H. pleuropneumoniae when serum of convalescent pigs was added.
authors.affiliation: Department of Herd Health and Pathology, Central Veterinary Institute, Lelystad, The Netherlands.
authors.forename: L A
authors.initials: LA
authors.lastname: Van Leengoed
authors.forename: E M
authors.initials: EM
authors.lastname: Kamp
authors.forename: J M
authors.initials: JM
authors.lastname: Pol
mesh_terms: D000818:Animals; D002470:Cell Survival; D002478:Cells, Cultured; D006190:Haemophilus / Q000502:physiology*; D008264:Macrophages / Q000166:cytology / Q000382:microbiology* / Q000648:ultrastructure; D008854:Microscopy, Electron; D011650:Pulmonary Alveoli / Q000166:cytology; D013047:Specific Pathogen-Free Organisms; D013552:Swine