Cellular component of lavage fluid from broilers with normal versus aerosol-primed airways

Previously, we reported that intratracheal administration of lipopolysaccharide elicited pulmonary hypertension (PH) in broilers reared under commercial conditions and in broilers reared in environmental chambers and pretreated with aerosolized red food colorant # 3 and propylene glycol (Red#3+PG), but not in control broilers reared in environmental chambers. The objective of the present experiment was to determine possible changes in the number or proportion of airway leukocytes that could contribute to the magnitude of the PH responses elicited in broilers. Birds were aerosolized for 40 min with a saturated mixture of Red#3+PG. After 24 h, a blood sample was taken, the broilers were killed, and a pulmonary lavage process was conducted in each bird. Leukocyte concentration (white blood cells/microL) and differential leukocyte counts (%) were measured in blood and lavage fluid. Leukocyte concentration in blood did not differ between groups, but the percentage of blood lymphocytes was lower in broilers from the Red#3+PG group compared with birds from the control group (52.4+/-2.9 and 56.9+/-2.9%, respectively). Cells recovered from the lavage fluid from both groups were primarily heterophils. The concentration of leukocytes was greater in the lavage fluid of broilers from the Red#3+PG group compared with broilers from the control group (763.2+/-158.7 and 402.9+/-62.6 white blood cells/microL, respectively), but the proportions among leukocytes were not different between the 2 groups. We propose that the increased concentration of leukocytes present within the airways was one of the components that enabled broilers pre-treated with aerosolized Red#3+PG to exhibit PH responses to intratracheal lipopolysaccharide.