A comparison ofnonsmokers, smokers with chronic obstructive pulmonary disease(COPD), and smokers without COPD found no statisticallysignificant difference in the number of PPARγ-positivemacrophages, but found an increased number ofPPARα-positive alveolar macrophages in smokers with COPD[34]. The gene discussed is PPARG; the disease is chronic obstructive pulmonary disease.