| Abstract: | Taxol, a plant alkaloid, promotes and stabilizes microtubule assembly in cells and cellfree systems. In the present study, the effects of taxol on various functional, morphologic, and biochemical phenomena in human peripheral blood PMN (Hypaque-Ficoll) were examined. Taxol (10(-7) M) inhibited PMN chemotaxis stimulated by N-formyl-methionyl-leucyl-phenylalanine (f-met-leu-phe) or endotoxin-activated serum by more than 60%. The inhibition was not readily reversed by washing, and taxol itself was not a chemoattractant, nor is it a secretagogue. Spontaneous nondirected migration, cell spreading on a glass surface, and orientation of cell organelles in response to a chemoattractant gradient were also inhibited by taxol. Taxol (10(-5) M) decreased killing of Staphylococcus aureus, but did not alter phagocytosis of heat-killed Candida or hexose monophosphate shunt activity in resting or stimulated PMN. Ultrastructural studies showed that PMN incubated in f-met-leu-phe, taxol, or both had increased (p less than 0.001) numbers of centrosome-associated microtubules, and the microtubules of cells incubated in taxol with or without f-met-leu-phe were organized into bundles. Taxol (10(-5) M) markedly inhibited post-translational tyrosinolation of alpha-chains of tubulin in both resting and f-met-leu-phe-stimulated PMN. The data indicate that taxol inhibits PMN locomotion and bacterial killing, supporting a role for microtubules in these processes. The ultrastructural and biochemical data also support the view that taxol mediates its effects on PMN by its effect on microtubules. |
