Submitted to: American College of Veterinary Pathologists Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: June 25, 1996
Publication Date: N/A
Technical Abstract: CD18 is the beta 2 subunit of the leukocyte adhesion 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, leukocytes lacking CD18 can enter the lumen of pulmonary alveoli. In order to determine whether CD18 mediates passage into pulmonary bronchi, 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 bronchoscopy and necropsied at 2.5 hours post-inoculation (PI). BLAD cattle (CD18- neutrophils) had few neutrophils within the walls and lumens of bronchi, whereas control cattle (CD18+ neutrophils) had dense infiltrates of cells within bronchial adventitia, lamina propria, and lumen. Differences in the degree of infiltration were quantitated by computerized image analysis. This work suggests that CD18 mediates passage of neutrophils into bronchi during the early stages of acute inflammation.