Participants in this study must be between the ages of 18 and 45 years and have no general health concerns and do not have allergies or asthma. If qualified, participants will come to the study site up to 3 times over about a 3-week period. This study involves answering questions about your medical history, having a physical exam, urine pregnancy tests for females who might be able to have children, and breathing tests. You will also have a blood draw to test for bleeding problems and an allergy skin test to see if you are allergic to common things. If it is safe for you, you will have a bronchoscopy. A bronchoscopy is a medical procedure to get samples of cells and small pieces of tissue (biopsies) from your lungs.