Differences in lymphocyte profile between BAL fluid and human lung tissue from patients with interstitial lung...

Bronchoalveolar lavage (BAL) is a technique that samples the inflammatory cells from distal airways and alveoli; however, it is unclear whether or not cellular profiles in the BAL fluid reflect the cellular components of the lung parenchyma in interstitial lung disease (ILD). The aim of this study is to compare immunophenotypes of lymphocytes between BAL fluid and human lung tissue from patients with ILD. Fourteen consecutive patients with ILD who underwent BAL and surgical lung biopsy were enrolled. The diagnosis of ILD was confirmed by the presence of clinical symptoms and impaired respiratory function and on high-resolution computed tomography (CT) of the chest. Mononuclear cells in BAL were immunophenotyped for the expression of CD3, CD4, CD8, CD19, CD45, and CD103 by flow cytometry. Lung tissue obtained by surgical biopsy was digested with collagenase and then centrifuged to extract parenchymal cells. Isolated cells were also immunophenotyped for the same CD expression. Frequencies of positive cells were compared statistically between BAL and different lobes. Seven out of 14 patients were diagnosed clinically as suffering idiopathic interstitial pneumonia. Frequency of CD19+ cells from BAL was significantly lower than that from the upper/middle lobes (P < 0.05). Frequency of CD103+ cells from BAL was significantly higher than that from the upper/middle lobes and the lower lobe (P = 0.01 and P < 0.05, respectively). Comparison between different lobes demonstrated that the frequency of CD4+ cells from the upper/middle lobes was significantly lower than that from the lower lobe (P < 0.05). The results suggest that lymphocyte immunophenotype profiles from BAL may not reflect those in the inflammatory tissue of ILD.