RecruitingProcedureEvaluating Clonogenic Epithelial Cell Populations in Patients With Bronchiolitis Obliterans SyndromeThis study investigates a type of cell, called abnormal clonogenic epithelial cells, in patients with bronchiolitis obliterans syndrome who have had an donor stem cell transplant or a lung transplant. Learning more about clonogenic cells in these patients may help doctors to detect signs of bronchiolitis obliterans syndrome earlier in future patients.