Y. Oghiso et al., CYTOTOXICITY OF FIBROGENIC ASBESTOS AND SILICA ON MURINE PULMONARY ALVEOLAR MACROPHAGE COLONY-FORMING CELLS, Inhalation toxicology, 5(3), 1993, pp. 303-311
Toxicity of fibrogenic asbestos and silica particles on the in vitro c
olony-forming capacity of murine pulmonary alveolar macrophages (PAM)
was tested to elucidate the possibility that the proliferation or the
maintenance of the PAM population could be affected by inhaled substan
ces. Intratracheal instillation of crocidolite asbestos or Min-u-sil s
ilica particles into mice induced significant and persistent reduction
of alveolar macrophage colony-forming cells (AM-CFC) during the perio
d of 1 to 6 months after treatments as compared to untreated control o
r groups of mice administered with nonfibrogenic TiO2 particles. Total
numbers of PAM recovered by bronchoalveolar lavage, however, were not
significantly different from the controls after asbestos or silica in
stillation. Instead, inflammatory exudation of polymorphonuclear leuko
cytes, lymphocytes, and monocytes significantly increased in the group
s of asbestos- or silica-instilled animals, but not in TiO2-instilled
mice. These data suggest that instilled fibrogenic particles have a cy
totoxic effect on the proliferation and differentiation of PAM, while
total PAM population could be maintained by recruitments of mononuclea
r phagocytes (monocytes) following inflammation or chemotactic events.