Lymphocyte subsets in lung tissues of non-specific interstitial pneumonia and pulmonary fibrosis associated with collagen vascular disorders: Correlation with CD4/CD8 ratio in bronchoalveolar lavage

This study was designed to evaluate the distribution of lymphocyte subsets in lung specimens that were obtained by open-lung biopsy from 8 patients wi th idiopathic nonspecific interstitial pneumonia/fibrosis (NSIP) and 10 pat ients with pulmonary fibrosis associated with collagen vascular disorders ( PF-CVD). Distributions of B lymphocytes, CD4-positive T lymphocytes, and CD 8-positive T lymphocytes were evaluated immunohistochemically and compared with the cell composition in BALF. Correlation between CD4/CD8 ratios in br onchoalveolar lavage fluids (BALF) and CD4/CD8 ratios in lung tissues was a lso examined. B lymphocytes were mostly restricted in lymphoid follicles. C D4-positive T lymphocytes were observed inside and around lymphoid follicle s and in the thick fibrotic wall of reconstructed alveoli with fibrosis. In contrast, CD8-positive T lymphocytes were diffusely distributed, especiall y in relatively thin alveoli. Correlation was weak between CD4/CD8 ratios i n lung tissue and CD4/CD8 ratios in:BALF. However, even in patients with ve ry low CD4/CD8 ratios in BALF, many CD4 lymphocytes were observed in lung t issues, suggesting that CD8-positive lymphocytes diffusely distributed in t hin alveolar architecture were more easily recovered in BALF than CD4-posit ive lymphocytes. Therefore, a low CD4/CD8 ratio in BALF may indicate that t he alveolar structure was not severely reconstructed by fibrosis, This is t he first report that compared lymphocyte subsets in lung tissues and in BAL F.