Effects of low concentrations of 3-carene on alveolar macrophages in vitro

Rat alveolar macrophages (AM) were incubated with the monoterpene 3-carene in vitro at the concentrations 0, 0.005, 0.05, 0.5 and 5.0 microM in culture medium for 75 min. A dose-dependent relationship was found between the cell viability and the 3-carene concentration. At 5.0 microM 3-carene, 98% of the AM were dead. The phagocytosis of heat-killed yeast particles was significantly decreased and the attachment of particles to the cell surface significantly increased at 0.5 microM 3-carene. Electron microscopy showed that about 50% of the AM lacked or had very few surface protrusions after incubation in 0.5 microM 3-carene. Thus, 3-carene seemed to affect mainly the engulfment of particles. Surfactant, 0.5 mg/ml as Curosurf, added to the incubation medium, did not affect the AM reaction to 3-carene exposure.