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

Abstract

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.

Metabolic activity of neutrophils is elevated in chronic obstructive pulmonary disease: Are we sure?

“…Vaidyanathan and Damodar have recently reported that there is an increase in metabolic activity of neutrophils in COPD, which possibly contributes toward lung tissue damage in chronic obstructive pulmonary disease (COPD) subjects. [ 1 ] This letter involves a critical analysis of the observations made by Vaidyanathan and Damodar.…”

“…However, I would like to draw the attention toward the most recent published research by Shanmugam et al .,[ 2 ] who happen to report similar findings as that of Vaidyanathan and Damodar. [ 1 ]…”

“…Second, the authors have compared the tendency for activation of neutrophils on exposure to Escherichia coli endotoxin of COPD patients and healthy individuals. [ 1 ] However, it was difficult to understand why the authors particularly select E. coli endotoxin to activate the neutrophils, rather than any other bacterial or chemical stimulation.…”

“…Third, the authors have recruited the COPD subjects according to Global initiative for Chronic Obstructive Lung Disease (GOLD) and observed that 87% of the COPD patients had a smoking history. [ 1 ] There is no explanation regarding how the remaining 13% COPD subjects were recruited in the study. In addition, the authors have reported that the duration of smoking history ranged from 0 to 50 years,[ 1 ] indicating the variability of COPD subjects recruitment and the introduction of sample biases.…”

“…Fourth, it can be inferred from the observations that neutrophil percentage among stimulated COPD group is higher than nonstimulated group. [ 1 ] Furthermore, the authors have mentioned that the 33% of COPD subjects have received doxofylline concurrently. [ 1 ] There is a lack of information whether the increase in neutrophil percentage among stimulated group is significantly higher compared to nonstimulated group.…”