Modulation of cytoskeleton assembly capacity and oxidative response in aged neutrophils.

Several reports have emphasized that aged polymorphonuclear cells (PMN) exhibit an impairment of superoxide anion (O2-) generation when triggered with formyl-methionyl-leucine-phenylalanine (FMLP) in comparison to the younger counterpart. Since microfilaments and microtubules are involved in PMN-mediated functions, in a group of old donors we assessed the effects of either actin stabilizing and disrupting agents, i.e. phalloidin and cytochalasin B, or microtubule stabilization or disruption by taxol and colchicine, respectively, on FMLP-triggered neutrophil oxidative responsiveness. Results show that phalloidin treatment, at a concentration ranging from 10(-6) to 10(-8) M, gave rise to an inhibition of O2- release by aged PMN, while the same effect was seen in similarly treated young cells at a concentration of 10(-7) M only. On the contrary, cytochalasin B pretreatment led to an enhancement of O2- generation in both young and aged neutrophils, even if to a lower extent in the latter group. At the same time, taxol at 10(-8) M strength inhibited young cell responsiveness, while no effects were induced by colchicine treatment. Quite interestingly, elderly neutrophil function was negatively modulated by both microtubule affecting compounds. Altogether, these findings suggest the possible relevance of cytoskeletal affecting compounds in the modulation of FMLP-stimulated O2- release during senescence.