The fourth leading cause of death today in the United States is lung disease which is quite often treated by lung transplantation. Lung transplant recipients seem to carry a greater risk of developing obliterative bronchiolitis (OB) which has been linked to chronic rejection of the transplanted lungs. Some recent studies have produced data that suggests the number of fibroblast and epithelial cells present in bronchoalveolar lavage (BAL) correlates to the severity of OB. Establishing a biomarker that can be used in the diagnosis of OB is important, because no clinical test exists that can be used to directly diagnose the disease. In these studies we show the populations of low frequency cells (fibroblast and epithelial) within different BAL samples. Cells are counted and sorted by type via a panning method and work has been done to prove their phenotype with immunostaining. This is an important step as no other research has documented the relative frequencies of cell populations within BAL samples, and provides a foundation to develop a clinical assay for detection of those subpopulations.