Granulomatous pneumonitis induced by bacille Calmette-Guérin in the mouse and its treatment with cyclosporin A.

Granulomatous pneumonitis was induced intravenously by an injection of BCG, and changes in the population of cells from bronchoalveolar lavage (BAL) fluid were examined. Increased lymphocytes in BAL fluid, especially Lyt-1 positive T-lymphocytes, were observed after the development of granulomatous pneumonitis. Cyclosporin A (Cy A) administered for 5 days before and for 5 days after BCG injection clearly suppressed development of the granuloma. The BAL cell count and cell population became almost the same as those in naive animals. The increase in the number of Lyt-1 positive T cells was abrogated by Cy A treatment. These results suggested the important role of Lyt-1 positive T cells in the development of granulomas and the possible beneficial effect of Cy A in human granulomatous lung diseases.