title: Stimulation and suppression of the oxygenation activity of porcine pulmonary alveolar macrophages by Actinobacillus pleuropneumoniae and its metabolites.
abstract: The effects of Actinobacillus (Haemophilus) pleuropneumoniae and its metabolites on the oxygenation activity of porcine pulmonary alveolar macrophages (PAM) were studied, using a chemiluminescence technique. Actinobacillus pleuropneumoniae strains of serotypes 2, 3, and 9 in a dose of 1, 10, and 100 colony-forming units/macrophage first stimulated the oxygen radical production of PAM. After having reached a peak value, oxygenation activity decreased, finally resulting in total suppression of PAM. All these effects were neutralized by homologous convalescent pig sera that had been adsorbed onto inactivated A pleuropneumoniae strains. Moreover, cross-neutralization was shown between serotypes 2 and 3. Inactivated A pleuropneumoniae strains did not influence the oxidative activity of PAM. Undiluted and lower dilutions of sterile A pleuropneumoniae culture supernatants were toxic for PAM, whereas higher dilutions of the supernatants stimulated oxygen radical production of the macrophages. These effects were heat-sensitive and were neutralized by homologous convalescent pig sera. Cross-neutralization was shown between serotypes 2 and 3. These findings indicated that stimulation and inhibition of the oxygenation activity of PAM are attributable to heat-sensitive metabolites produced by A pleuropneumoniae.
authors.affiliation: Laboratory of Veterinary Bacteriology, Faculty of Veterinary Medicine, University of Gent, Belgium.
authors.forename: P
authors.initials: P
authors.lastname: Dom
authors.forename: F
authors.initials: F
authors.lastname: Haesebrouck
authors.forename: P
authors.initials: P
authors.lastname: De Baetselier
mesh_terms: D016977:Actinobacillus pleuropneumoniae / Q000276:immunology / Q000502:physiology*; D000818:Animals; D001427:Bacterial Toxins / Q000494:pharmacology; D002470:Cell Survival; D002478:Cells, Cultured; D005856:Germ-Free Life; D016676:Macrophages, Alveolar / Q000276:immunology / Q000378:metabolism* / Q000382:microbiology; D010084:Oxidation-Reduction; D013552:Swine / Q000276:immunology*
chemical_list: D001427:Bacterial Toxins