Sex hormones alter Th1 responses and enhance granuloma formation in the lung.

BACKGROUND The lung is one of the sites of granulomatous responses, which are characterized by the recruitment and organization of activated macrophages and lymphocytes. There have been several reports that have shown that some pulmonary granulomatous diseases, such as sarcoidosis and nontuberculous mycobacterial disease, are likely to be characterized by a preponderance in postmenopausal females. Although sex hormones have been shown to play an important role in the regulation of the immune system, the influence of sex hormones on pulmonary granuloma formation is still unclear. OBJECTIVES The purpose of this study was to assess whether sex hormones are involved in granulomatous inflammation and to evaluate how sex hormones modulate this response in the lung. METHODS Ovariectomized rats were used as an experimental postmenopausal model in which chronic pulmonary granulomatous inflammation was induced by intravenous injection of complete Freund's adjuvant. RESULTS Histological analysis of lung tissues demonstrated enhancement of granuloma formation in the ovariectomized group. Such enhanced granuloma formation was significantly associated with generalized Th1-biased cytokine production in the bronchoalveolar lavage fluid. CONCLUSION These results indicate that sex hormones play an important role in pulmonary granuloma formation by altering the Th1 responses.