EFFECTS OF SPERMIDINE ON FUNCTION AND ULTRASTRUCTURE OF ALVEOLAR MACROPHAGES

It is known that spermidine and other naturally occurring polyamines a ccumulate in rat lung slices by an energy-dependent uptake process and that alveolar macrophages (AM) have a greater rate of uptake than has the total lung cell population. In the present study rat AMs were inc ubated with spermidine, which resulted in a marked and significant (P < 0.002) decrease in phagocytosis of heat-killed yeast cells at concen trations 0.2 and 0.5 mM and a tendency to decrease at 0.05 mM. The num ber of microtubules surrounding the centrioles was measured using elec tron microscopy and appeared to be decreased at concentrations 0.2 and 0.5 mM. There was no affect on phagolysosomal pH. The results suggest that spermidine might affect the defense against inhaled pollutants a nd microbes, especially when spermidine levels are increased, as they are under conditions with high mitotic activity,e.g., in tumors. (C) 1 994 Academic Press, Inc.