Phagocytes
Alveolar macrophages remove foreign material that escapes the mucociliary defense mechanism. Nonpathogenic
particles and microbes are handled by simple phagocytic activity and are removed in the mucus flow or by the lymphatic system. Pathogenic microorganisms are neutralized with the aid of secre-tions such as lysozyme, interferons, proteolytic enzymes and enzyme inhibitors, opsonins, lactoferrins, complement factors, oxygen radicals and free radical scavengers,
and specific immunoglobulins in the mucus. Neutrophils, with phagocytic activity and a potent array of pathogen-killing enzymes, are recruited from
the blood into the alveolus and assist the macrophages
in the phagocytic activity. In healthy pigs, the normal
ratio between the cellular elements in the bronchoalveolar
mucus is 70–90% alveolar macrophages, 5–18%
lymphocytes, 4–12% neutrophils, and up to 5% eosinophilic
granulocytes (Jolie et al. 2000; Neumann et al.
1985). The phagocytic cell system also comprises intravascular
macrophages, which in the pig are particularly
numerous in the pig lungs (Bertram 1985; Ohgami
et al. 1989).
PhagocytesAlveolar macrophages remove foreign material that escapes the mucociliary defense mechanism. Nonpathogenicparticles and microbes are handled by simple phagocytic activity and are removed in the mucus flow or by the lymphatic system. Pathogenic microorganisms are neutralized with the aid of secre-tions such as lysozyme, interferons, proteolytic enzymes and enzyme inhibitors, opsonins, lactoferrins, complement factors, oxygen radicals and free radical scavengers,and specific immunoglobulins in the mucus. Neutrophils, with phagocytic activity and a potent array of pathogen-killing enzymes, are recruited fromthe blood into the alveolus and assist the macrophagesin the phagocytic activity. In healthy pigs, the normalratio between the cellular elements in the bronchoalveolarmucus is 70–90% alveolar macrophages, 5–18%lymphocytes, 4–12% neutrophils, and up to 5% eosinophilicgranulocytes (Jolie et al. 2000; Neumann et al.1985). The phagocytic cell system also comprises intravascularmacrophages, which in the pig are particularlynumerous in the pig lungs (Bertram 1985; Ohgamiet al. 1989).
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