Study objectives: The purpose of this study was to explore the relationship between cigarette smoking and COPD on the number of formyl methionyl leucyl phenylalanine (FMLP) receptors on peripheral neutrophils.
Design and participants: Three groups of subjects were studied: subjects with COPD (n = 13), healthy smokers (n = 6), and healthy nonsmokers (n = 6).
Interventions: Fifty milliliters of venous blood were collected from each subject, and neutrophils were isolated. Neutrophil FMLP receptor numbers were determined by incubating with tritiated FMLP at six doubling concentrations from 1.4 to 45 pmol. Three of the subjects from group 1 (the COPD group) were current smokers, and we elected to analyze these subjects as a separate group.
Measurements and results: The analysis of variance looking at the three factors—FMLP, COPD and smoking—showed significant differences among levels of FMLP (p = 0.0001), as would be expected, and also overall smoking vs nonsmoking (p = 0001) and COPD vs non-COPD (p = 0.02). Within each level of FMLP, there was only one instance of a significant difference between COPD nonsmokers and normal nonsmokers, and no instance of a significant difference between COPD smokers and normal smokers. At five of the six concentrations of tritiated FMLP, smoking was a significant factor.
Conclusions: This study suggests that the overriding influence on peripheral neutrophil FMLP receptor numbers is current smoking rather than the presence of COPD.