Reaction of the avian respiratory system to intratracheally administered avirulent Salmonella typhimurium.

Chickens were inoculated intratracheally (IT) with the SR-11 Salmonella typhimurium deletion mutant x4062 strain. Data collected for 8 days postinoculation (PI) were: signs of respiratory and gastrointestinal disease; histological lesions; the influx, phagocytic proportion, and phagocytic capacity of avian respiratory phagocytes (ARPs); and the proportion of granulocytes vs. macrophages in the lung tissues and lavage fluids of the lungs and air sacs. S. typhimurium-inoculated chickens had no clinical signs of gastrointestinal or respiratory disease but had various degrees of inflammatory changes in the lungs. At 5 hr PI, S. typhimurium-inoculated chickens had approximately 53-fold more ARPs than mock-inoculated controls. Between 26 hr and 8 days PI, the number of ARPs from S. typhimurium-inoculated birds was not significantly higher than the number from the mock-inoculated controls. Flow cytometric analysis of ARPs demonstrated that the proportion of phagocytic ARPs and the phagocytic capacity of ARPs from S. typhimurium-inoculated chickens were significantly higher between 5 and 26 hr PI than those of the ARPs from mock-inoculated chickens. Kinetic changes over 8 days in the granulocyte/macrophage ratios in the lavage fluids, as compared with kinetic changes in the lung tissues, suggested that the granulocytes generally represent a much higher proportion of the ARPs, and egress earlier and in much larger numbers from the tissues to the lumen of lungs and air sacs than do macrophages.     

Lack of formyl-methionyl-leucyl-phenylalanine receptors on porcine neutrophils

The response of blood neutrophils to the chemotactic peptide formyl-methyl-leucyl-phenylalanine varies among species. Our results indicate that this peptide does not activate the respiratory burst of porcine neutrophils. Specifically, concentrations less than or equal to 10(-6) M did not cause production of either superoxide or hydrogen peroxide. Studies designed to delineate the biochemical deficit responsible for these results indicated that these cells do not express specific chemotactic peptide receptors on the external surface of the plasma membrane. Although these data do not rule out the possibility that internal stores of chemotactic peptide receptor exist, attempts to induce expression of the receptor by priming the cells with either lipopolysaccharide or calcium ionophore were unsuccessful.     

Cellular defense of the avian respiratory system: effects of Pasteurella multocida on respiratory burst activity of avian respiratory tract phagocytes

The respiratory tract of healthy chickens contain few free-residing phagocytic cells. Intratracheal inoculation with Pasteurella multocida stimulated a significant (P less than 0.05) migration of cells to the lungs and air sacs of White Rock chickens within 2 hours after inoculation. We found the maximal number of avian respiratory tract phagocytes (22.9 +/- 14.0 x 10(6] at 8 hours after inoculation. Flow cytometric analysis of these cells revealed 2 populations on the basis of cell-size and cellular granularity. One of these was similar in size and granularity to those of blood heterophils. Only this population was capable of generating oxidative metabolites in response to phorbol myristate acetate. The ability of the heterophils to produce hydrogen peroxide, measured as the oxidation of intracellularly loaded 2',7'-dichlorofluorescein, decreased with time after inoculation. These results suggest that the migration of heterophils, which are capable of high levels of oxidative metabolism, to the lungs and air sacs may be an important defense mechanism of poultry against bacterial infections of the respiratory tract.