A00005CD18-Mediated Passage of Neutrophils into Bovine Bronchioles and Bronchi during peracute Pneumonia
Mark R. Ackermann(1), ME Kehrli, Jr.(2), KB Brogden(2), AF Florance(1)
(1)Iowa State University, Ames, IA USA (2)USDA/ARS-NADC, Ames, IA USA
Abstract:
CD18 is the beta subunit of the beta-2 integrin molecules LFA-1, Mac-1
and p150,95. These molecules are expressed on the plasma membrane of
leukocytes and mediate passage across the vascular wall and perivascular
matrix. In the lung, we have shown that neutrophils lacking CD18 can
enter the lumen of pulmonary alveoli during acute (<6 hours)
pneumonia. In order to determine whether CD18 mediates passage into
the pulmonary bronchi and bronchioles, 3 Holstein calves homozygous
for Bovine Leukocyte Adhesion Deficiency (BLAD), thereby lacking CD18
expression (CD18-), and 3 age and breed matched control Holstein cattle
(CD18+) were inoculated with Pasteurella haemolytica A1 via
fiberoptic bronchoscope and necropsied 2 hours post-inoculation (PI).
Sections of lung were stained for neutrophils and intensity of
neutrophilic infiltration was determine by computerized image analysis.
BLAD calves (CD18- neutrophils) had few neutrophils within the lumen
and walls of bronchioles and bronchi whereas calves with normal CD18
expression (CD18+ neutrophils) had dense infiltrates within the lumen,
epithelium and lamina propria. This work suggests that during the
peracute inflammatory response, CD18 mediates passage of neutrophils
into bronchioles and bronchi. Presumably CD18 is needed for passage
through the extensive extracellular matrix.
Comments:
Address questions and comments about this abstract to Mark R. Ackermann ( mackerma@iastate.edu).
Previously presented at American College of Veterinary Pathologists on December 3, 1996.