Interleukin-5 Receptor Expression in COPD

During this study the subjects will have a bronchoscopy where the study team will collect airway samples to see how the subjects express certain cells. The subjects will also have two blood draws to provide information on the number of inflammatory cells that are present in their blood. This will help the study team determine if mepolizumab might be able to be used in more patients with COPD. The use of mepolizumab in COPD subjects with elevated blood eosinophils has been proven effective. However, the cellular mechanisms in the COPD population are unknown, including the extent to which these subjects express IL-5 in their airway and whether eosinophils are the sole target. Through this study the study team plans to provide proof of concept that mepolizumab could target additional IL-5-expressing immune cells in the airway, including especially PMNs. The study team will also investigate additional feasible biomarkers that could be utilized to predict mepolizumab responsiveness in COPD. The study team is hoping to determine if COPD patients with elevated blood eosinophils will demonstrate increased concentrations of IL-5 in their bronchoalveolar lavage (BAL) fluid and increased expression in their BAL of CD125+ PMNs. To address this hypothesis, the following specific aims will be addressed: To define the expression of IL-5R on PMNs in COPD and to demonstrate elevated concentrations of IL-5 in BALF obtained from COPD subjects with blood eosinophils (≥300/µL).