Proliferation of alveolar macrophages in hyperoxia

The effect of oxygen on the proliferative response of alveolar macrophages (AMs) was investigated. Alveolar macrophages cultured in hyperoxic atmosphere (95% O2 + 5% CO2) for 18 hours showed increased incorporation of [3H]-thymidine and proliferation in contrast to those cultured in a control atmosphere (95% air + 5% CO2). The proliferating cell was shown to be a macrophage by morphology, esterase staining, and phagocytic ability. The results suggest an oxygen-induced proliferation of AMs that may play a critical role in AM influx into the alveoli particularly at times of hyperoxia, eg, the neonatal period.