Surface morphology and morphometry of rat alveolar macrophages after ozone exposure

Abstract

As the ultrastructural data on the effects of ozone on pulmonary alveolar macrophages (PAM) are lacking, transmission (TEM) and scanning (SEM) electron microscopy were performed on rat RAM present in alveolar lavages following exposure to ozone. Rats were continuously exposed for 7 d to ozone concentrations ranging from 0.25 to 1.50 mg/m³ for 7 d followed by a 5‐d recovery period. Additionally, morphometry on lung sections was performed to quantitate PAM. In a second experiment rats were continuously exposed to 1.50 mg O₃/m³ for 1, 3, 5, or 7 d. To study the influence of concurrent ozone exposure and lung infection, due to Listeria monocytogenes, rats were exposed for 7 d to 1.50 mg O₃/m³ after a Listeria infection.

The surface area of lavaged control PAM was uniformly covered with ruffles as shown by SEM and TEM. Exposure to 0.5 mg ozone/m³ for 7 d resulted in cells partly covered with microvilli and blebs in addition to normal ruffles. The number of large size PAM increased with an increase in ozone concentration. After 1 d of exposure, normal‐appearing as well as many small macrophages with ruffles and scattered lymphocytes were seen. Lavage samples taken after 5 or 7 d of exposure showed an identical cell composition to that taken after 3 d of exposure. After Listeria infection alone, lavage samples consisted of mainly lymphocytes and some macrophages. Small quantitative