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

Ochs, D.L.; Toth, T.E.; Pyle, R.H.; Siegel, P.B.

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

1988

Ochs, D.L. | Toth, T.E. | Pyle, R.H. | Siegel, P.B.

The respiratory tract of healthy chickens contain few free-residing phagocytic cells. Intratracheal inoculation with Pasteurella multocida stimulated a significant (P < 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.

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