Macrophage activation by N-acetyl-cysteine in COPD patients

The effect of in vivo and in vitro N-acetylcysteine (NAC) treatment on destructive activity of macrophages against Candida from COPD patients has been evaluated. Patients received NAC (600 mg) or placebo orally 3 times a day for 15 days and bronchoalveolar lavage (BAL) fluid and peripheral blood were collected before and at the conclusion of treatment. In our system, NAC treatment was not able to modulate antifungal activity of alveolar macrophages, peripheral blood monocytes (PBM), and polymorphonuclear leukocytes. On the contrary, in vitro NAC treatment at appropriate doses (10 micrograms/ml) significantly enhanced antifungal activity of PBM from COPD patients. This phenomenon is mediated by augmented phagocytic activity and phagosome-lysosome fusion. The lack of correlation between in vivo and in vitro studies could be ascribed to differences in the intracellular concentration of the drug that in vivo does not reach levels capable of inducing macrophage activation. We speculate that in COPD patients who undergo long-term NAC treatment, appropriate schedules and doses of the drug could augment resistance against microbial infections which are often life-threatening in these patients.