Lymphocyte phenotypes in bronchoalveolar lavage and lung tissue in sarcoidosis and idiopathic pulmonary fibrosis.

To determine whether the lymphocytes recovered by bronchoalveolar lavage (BAL) are representative of the cells found in lung tissue, we identified and enumerated lymphocyte phenotypes directly in lung tissue and lavage fluid with monoclonal antibodies (Leu 4-total T, Leu 3-helper T, Leu 2-suppressor/cytotoxic T cells) and an avidin-biotin peroxidase method in 6 patients with sarcoidosis and 6 patients with idiopathic pulmonary fibrosis (IPF). We found that the absolute numbers of each phenotype and the ratios of Leu 3/Leu 4, Leu 2/Leu 4, and Leu 3/Leu 2 in lavage fluid and tissue correlated well for both groups of patients. This supports the notion that the lymphocytes recovered by BAL are representative of the cells present in the lung. However, when cell recovery was expressed as the number per milliliter of recovered lavage fluid, there were no significant correlations between lavage fluid and tissue for any phenotype in the IPF group. The degree of restrictive impairment was significantly greater and the lavage fluid recovery was significantly lower in this group than in the sarcoid group. Thus, the lymphocytes recovered by BAL appear to mirror the types of cells found in lung tissue in these 2 forms of diffuse interstitial disease, but this relationship may not hold when there is a severe restrictive impairment and a low recovery of lavage fluid.