Functional activities of alveolar macrophages in rat exposed to hyperoxia (normobaric O2)

Pulmonary alveolar macrophages (PAM) from rats exposed to 100% normobaric oxygen for 24, 48 and 65 h were collected by bronchoalveolar lavage. The cell yield was not modified by a 24 h exposure, but after 48 h, the number of PAM decreased and polymorphonuclear leucocytes were found in the lavage liquid. These modifications were amplified after a 65-h exposure. The percentage of uptake of Staphylococcus aureus after 30 min of incubation with PAM from rats exposed for 24 h and 48 was unchanged. No impairment of intracellular bactericidal activity toward S. aureus could be demonstrated in PAM from rats exposed to O2 for 24 h. After 48 h of O2 exposure, a slightly significant decrease in intracellular bactericidal activity was found only after 120 min of incubation. Nitroblue tetrazolium reduction and chemiluminescence were measured in PAM from O2-exposed and control rats: no modification could be demonstrated after 24 and 48 h of exposure. These results suggest that the PAM is relatively resistant to oxygen toxicity.