Interaction of bovine alveolar macrophages with Pasteurella haemolytica A1 in vitro: modulation by purified capsular polysaccharide.
Preincubation of bovine alveolar macrophages with Pasteurella haemolytica A1 purified capsular polysaccharide markedly reduced the phagocytosis of P. haemolytica A1 in vitro in a dose-dependent manner. Both the percentage of macrophages with intracellular P. haemolytica and the mean number of bacteria per ingesting macrophage were decreased by treatment with capsular polysaccharide. Untreated bovine alveolar macrophages had little ability to kill P. haemolytica A1 in vitro at bacteria to macrophages ratios of 1 to 1 or greater; at lower ratios of bacteria to macrophages (1 to 3 or less) modest killing was observed. Preincubation with capsular polysaccharide impaired phagocytosis and killing of P. haemolytica A1 by alveolar macrophages even when the macrophages outnumbered the bacteria. These data indicate that P. haemolytica capsular polysaccharide inhibits the ability of alveolar macrophages to defend against P. haemolytica, as has been reported previously for bovine neutrophils.
Czuprynski
C J
CJ
Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin, Madison.
Noel
E J
EJ
Adlam
C
C
D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D004306:Dose-Response Relationship, Immunologic; D008264:Macrophages / Q000276:immunology / Q000382:microbiology*; D010325:Pasteurella / Q000276:immunology*; D010587:Phagocytosis; D011135:Polysaccharides, Bacterial / Q000276:immunology*; D011650:Pulmonary Alveoli / Q000166:cytology
D011135:Polysaccharides, Bacterial