Age-dependent neutrophil and blood flow responsiveness in acute
pulmonary inflammation in rabbits.
Hyde, Dallas M., Gregory P. Downey, Fern Tablin, Sanna Rosengren*,
Patricia C. Giclas, Peter M. Henson and G. Scott Worthen
Departments of Pediatrics and Medicine, National Jewish Center for
Immunology and Respiratory Medicine, 1400 Jackson St., Denver,
Colorado, Department of Anatomy, Physiology and Cell Biology,
University of California, Davis, California, Department of Medicine,
Clinical Sciences Division, 1 Kings College Circle, University of
Toronto, Toronto, Ontario, Canada M5S 1A8
APStracts 3:0193L, 1996.
Diminished ability of neonatal neutrophils to orient and move in a
chemotactic gradient has been linked to compromised pulmonary host
defense. We investigated whether deficiency of neonatal neutrophil
function in vitro was evident in acute pulmonary inflammation.
Analysis of neutrophils in vitro showed impaired chemotaxis in 4 week
old as compared with adult rabbits. In vivo directed migration of
labeled neutrophils into the alveolar space of adult rabbits in
response to C5f instillation was significantly less for neutrophils
donated from 4 week olds as compared with those from adults. In
contrast, there were no differences in the alveolar accumulation of 4
week old and adult labeled neutrophils in 4 week old rabbits in
response to C5f instillation, although the response showed a shorter
time course than seen in adult rabbits. Adult rabbits diverted 46% of
the blood away from the right cranial lung lobe, while 4 week old
rabbits showed no change in blood flow after C5f instillation.
Megakaryocytes (a source of blood flow mediators) were 3.2 fold
greater in adult as compared with 4 week old lung. These data suggest
that the lack of blood flow diversion from inflamed neonatal lung
increases neutrophil migration into alveoli, allowing for
preservation of an inflammatory response despite neutrophil
deficiencies in chemotaxis.
Received 12 July 1996; accepted in final form 21 October 1996.
APS Manuscript Number L216-5.
Article publication pending Am. J. Physiol. (Lung Cell. Mol.
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 13 November 1996