Comparative in vitro study of interactions between particles and respiratory surface macrophages, erythrocytes, and epithelial cells of the chicken and the rat
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Date
2008Author
Kiama, SG
Adekunle, JS
Maina, JN
Type
ArticleLanguage
enMetadata
Show full item recordAbstract
In mammals, surface macrophages (SMs) play a foremost role in protecting the respiratory system by engulfing and
destroying inhaled pathogens and harmful particulates. However, in birds, the direct defense role(s) that SMs
perform remains ambiguous. Paucity and even lack of SMs have been reported in the avian respiratory system. It has
been speculated that the pulmonary defenses in birds are inadequate and that birds are exceptionally susceptible
to pulmonary diseases. In an endeavour to resolve the existing controversy, the phagocytic capacities of the
respiratory SMs of the domestic fowl and the rat were compared under similar experimental conditions by exposure
to polystyrene particles. In cells of equivalent diameters (8.5
μ
m in the chicken and 9.0
μ
m in the rat) and hence
volumes, with the volume density of the engulfed polystyrene particles, i.e. the volume of the particles per unit
volume of the cell (SM) of 23% in the chicken and 5% in the rat cells, the avian cells engulfed substantially more
particles. Furthermore, the avian SMs phagocytized the particles more efficiently, i.e. at a faster rate. The chicken
erythrocytes and the epithelial cells of the airways showed noteworthy phagocytic activity. In contrast to the rat
cells that did not, 22% of the chicken erythrocytes phagocytized one to six particles. In birds, the phagocytic
efficiencies of the SMs, erythrocytes, and epithelial cells may consolidate pulmonary defense. The assorted cellular
defenses may explain how and why scarcity of SMs may not directly lead to a weak pulmonary defense. The
perceived susceptibility of birds to respiratory diseases may stem from the human interventions that have included
extreme genetic manipulation and intensive management for maximum productivity. The stress involved and the
structural–functional disequilibria that have occurred from a ‘directed evolutionary process’, rather than weak
immunological and cellular immunity, may explain the alleged vulnerability of the avian gas exchanger to diseases
Citation
Journal of AnatomyPublisher
Department of Veterinary Anatomy and Physiology, University of Nairobi School of Anatomical Sciences, University of the Witwatersrand, Johannesburg