Increased metabolic activity of neutrophils in patients with chronic obstructive pulmonary disease

AIMS: To compare the metabolic activity of peripheral neutrophils in patients diagnosed with chronic obstructive pulmonary disease (COPD) with that of healthy, nonsmoking volunteers. MATERIALS AND METHODS: Venous blood samples were taken from patients diagnosed with COPD as well as from healthy nonsmokers. Each sample was subjected to the nitro blue tetrazolium (NBT) test in which neutrophils exhibiting elevated metabolic activity were detected by light microscopy. The test was repeated after stimulation with Escherichia coli (E. coli) endotoxin with fresh samples. Neutrophils showing dye uptake were then counted in each case. RESULTS: We found that the mean numbers of activated neutrophils without and with the addition of endotoxin were 19% and 23%, respectively, in the control group and 56% and 62%, respectively, in the test group. Two-sample t-test statistic revealed that there was a significant (P < 0.01) increase in neutrophilic metabolic activity in patients with COPD as compared to that in healthy volunteers. This significance remained even after stimulation using E. coli endotoxin. CONCLUSION: The results hint at a potentially relevant pathogenic mechanism in COPD related to the metabolic activity of neutrophils. By exhibiting enhanced metabolic activity, neutrophils in the COPD patients are more likely to be involved in damaging lung tissues.