To this end, Maestrelli et al. [97] reported that the numbers of neutrophils expressing CD11b and CD18, but not CD11a or CD11c, were increased in smoking subjects (n = 33) with airway obstruction, compared to smokers without airway obstruction, and hypothesised that CD11b/CD18 expression by sputum neutrophils may represent a marker for the development of chronic airway obstruction among smokers. This evidence concerns the gene ITGAM and chronic obstructive pulmonary disease.