SHORT-TERM IN-VIVO EXPOSURE TO CIGARETTE-SMOKE INCREASES THE FLUORESCENCE IN RAT ALVEOLAR MACROPHAGES

Alveolar macrophages (AMs) from human smokers exhibit a strong intrace llular fluorescence. In order to study the mechanisms behind the fluor escence, we wanted to determine whether it could be induced by short t erm exposure to smoke. We therefore exposed rats for either one or fiv e days to cigarette smoke. AMs were recovered by bronchoalveolar lavag e (BAL), and their fluorescence was quantified by flow cytofluorometry . AMs from rats exposed to two cigarettes, on a single occasion, showe d an increased fluorescence compared to controls. The fluorescence was further enhanced by exposing rats to two cigarettes, for five consecu tive days. Larger and more granular/complex AMs were more fluorescent than smaller and less granular/complex cells. Smoke-exposed rats (five consecutive days) lavaged immediately after the exposure, had less ce lls in their BAL fluid than control animals. However, when rats were l avaged three smoke-free days after the exposure, the cell recovery inc reased, probably due to less airway obstruction. In conclusion, we fou nd that a short-term in vivo exposure to cigarette smoke results in an increased AM fluorescence. The findings can be one explanation for th e strong fluorescence seen in AMs from human smokers, possibly due to endocytosis of fluorescent material.