Expression of thioredoxin in granulomas of sarcoidosis: possible role in the development of T lymphocyte activation
- Toshiya Kouraa,
- Yasuhiro Gona,
- Shu Hashimotoa,
- Arata Azumab,
- Shoji Kudohb,
- Yuh Fukudac,
- Isamu Sugawarad,
- Junji Yodoie,
- Takashi Horiea
- aFirst Department of Internal Medicine, Nihon University School of Medicine, Tokyo, Japan, bFourth Department of Internal Medicine, Nippon Medical School, Japan, cFirst Department of Pathology, Nippon Medical School, Japan, dMolecular Pathology Division, The Research Institute of Tuberculosis, Japan Anti-Tuberculosis Association, Japan, eDepartment of Biological Response, Institute for Virus Research, Kyoto University, Japan
- Dr S Hashimoto, First Department of Internal Medicine, Nihon University School of Medicine, 30–1 Oyaguchikamimachi, Itabashi-ku, Tokyo 173–8610, Japan email:shuh{at}med.nihon-u.ac.jp
- Received 30 June 1999
- Revision requested 14 October 1999
- Revised 4 May 2000
- Accepted 17 May 2000
Abstract
BACKGROUND Activated T lymphocytes are one of the characteristic features of sarcoidosis. The mechanism of T cell activation, expressing various activation markers including interleukin 2 receptor (IL-2R), has been extensively investigated but the precise mechanism remains unknown. Although thioredoxin (TRX) displays a number of biological activities including IL-2R inducing activity, its role in the induction of IL-2R expression on T cells in sarcoidosis has not been determined. The expression of TRX and IL-2R in granulomas of patients with sarcoidosis has been studied to clarify a possible role for TRX in the induction of IL-2R expression.
METHODS Granulomas in specimens of lung tissue and lymph nodes from five patients with sarcoidosis were immunohistochemically stained with anti-TRX antibody and anti-IL-2Rα chain antibody and the concentration of TRX in the bronchoalveolar lavage (BAL) fluid from 20 patients with pulmonary sarcoidosis was measured.
RESULTS Granulomas in lung and lymph node tissue from patients with sarcoidosis showed strong reactivity with anti-TRX antibody. Positive staining was present in the macrophages, epithelioid cells, and Langhans' type giant cells but not in lymphocytes. IL-2R was expressed on lymphocytes in the same granulomas. By contrast, positive immunoreactivity was not found in lung tissue specimens from 12 control subjects. Concentrations of TRX in BAL fluid were higher in patients with pulmonary sarcoidosis (median (range) 122.6 (20.9–303.3) ng/ml) than in control subjects (32.9 (16.8–52.8) ng/ml, p<0.05).
CONCLUSIONS TRX is highly expressed and is locally produced by granulomas in patients with sarcoidosis. The coexistence of immunoreactive TRX and IL-2R in the same granulomas suggests that TRX might act as a local inducing factor for IL-2R expression on T cells.
