Effect of tilmicosin on chemotactic, phagocytic, and bactericidal activities of bovine and porcine alveolar macrophages.
OBJECTIVE
To evaluate chemotactic, phagocytic, and bactericidal activities of bovine and porcine alveolar macrophages (AM) exposed to tilmicosin.


METHODS
12 healthy calves and 12 healthy pigs.


METHODS
Lungs were obtained immediately after euthanasia; AM were collected by means of bronchoalveolar lavage and density gradient centrifugation. Chemotactic activity was evaluated by exposing AM to lipopolysaccharide or macrophage inhibitory peptide during incubation with tilmicosin. Phagocytic activity was evaluated by incubating AM with tilmicosin for 24 hours and then with tilmicosin-resistant Salmonella serotype Typhimurium. Bactericidal activity was evaluated by incubating AM with tilmicosin (0, 10, or 20 microg/ml for bovine AM; 0 or 10 microg/ml or 10 microg/ml but washed free of tilmicosin for porcine AM) and then with Mannheimia haemolytica (bovine AM) or with Actinobacillus pleuropneumoniae or Pasteurella multocida (porcine AM).


RESULTS
Tilmicosin had no significant effects on chemotactic or phagocytic activities of bovine or porcine AM. The time-course of bactericidal activity was best described by polynomial equations. Time to cessation of bacterial growth and area under the time versus bacterial number curve were significantly affected by incubation of AM with tilmicosin.


CONCLUSIONS
Results show that bactericidal activity of bovine and porcine AM was enhanced by tilmicosin, but not in proportion to the reported ability of AM to concentrate tilmicosin intracellularly. With or without exposure to tilmicosin, the time-course of bactericidal activity of bovine AM against M haemolytica and of porcine AM against A pleuropneumoniae or P multocida was too complex to be reduced to a simple linear equation.
Brumbaugh
Gordon W
GW
Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine, Texas A&M University, College Station, TX 77843, USA.
Herman
James D
JD
Clancy
Julianne S
JS
Burden
Kyland I
KI
Barry
Tracie
T
Simpson
R B
RB
López
Hector Sumano
HS
D016977:Actinobacillus pleuropneumoniae / Q000187:drug effects; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002417:Cattle / Q000276:immunology*; D002633:Chemotaxis / Q000187:drug effects*; D018942:Macrolides / Q000494:pharmacology*; D016676:Macrophages, Alveolar / Q000187:drug effects* / Q000276:immunology; D016978:Mannheimia haemolytica / Q000187:drug effects; D016979:Pasteurella multocida / Q000187:drug effects; D010587:Phagocytosis / Q000187:drug effects*; D013552:Swine / Q000276:immunology*; D013997:Time Factors; D015645:Tylosin / Q000031:analogs & derivatives* / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D018942:Macrolides; C052319:tilmicosin; D015645:Tylosin