Expression of IFN-c before and after treatment of oral lichen planus with 0.1% fluocinolone acetonide in orabase Pornpan Youngnak-Piboonratanakit 1 , Kittipong Dhanuthai 2 , Kobkan Thongprasom 1 , Pimporn Luckprom 1 , Wilairat Sarideechaigul 3 , Lakana Luangjarmekorn 1 , Miyuki Azuma 4 1 Department of Oral Medicine, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand; 2 Department of Oral Pathology, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand; 3 Department of Oral Medicine, Faculty of Dentistry, Naresuan University, Phitsanulok, Thailand; 4 Department of Molecular Immunology, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan BACKGROUND: Oral lichen planus (OLP) is a common chronic inflammatory mucosal disease in which T-cell- mediated immune responses are implicated in the path- ogenesis. The purpose of this study was to investigate the effect of 0.1% fluocinolone acetonide in orabase (FAO) on the in situ expression of IFN-c in patients with OLP. METHODS: Twenty OLP patients were enrolled in this study. Biopsy specimens and serum samples were obtained before and 1-month after the treatment with 0.1% FAO. In situ expression and serum levels of IFN-c were determined using immunohistochemistry and ELI- SA, respectively. RESULTS: The number of IFN-c-positive mononuclear cells in OLP lesions before the treatment was significantly higher as compared with that after the treatment. Simi- larly, the mean number of total mononuclear cells was clearly decreased after the treatment. However, the serum levels of IFN-c were not detectable. CONCLUSIONS: Our results suggest that IFN-c expres- sion in OLP tissue may involve in the immunopathogenesis and the treatment with 0.1% FAO had an immunomodu- lating effect on the decrease of IFN-c. J Oral Pathol Med (2009) 38: 689–694 Keywords: fluocinolone acetonide; interferon-c; oral lichen planus Introduction Oral lichen planus (OLP) is a common chronic inflam- matory mucocutaneous disease in which T-cell mediated immune dysfunction is implicated in its complex etio- pathogenesis (1). The inflammatory response in OLP is characterized by the accumulation of CD4 + T helper 1 (Th1) lymphocytes representing a delayed type hyper- sensitivity reaction to an as-yet-undetermined antigen (2). Th1 immune responses require the participation of both CD4 + Th and CD8 + cytotoxic T lymphocytes (CTL). The large amount of cytokines released from various cells including affected keratinocytes and acti- vated T lymphocytes contribute to the regulation of local immune responses such as facilitating the recruit- ment of lymphocytes, proliferation and differentiation of inflammatory cells, induction of adhesion molecules, and damage of basal keratinocytes leading to cell apoptosis (2, 3). A type II interferon, interferon-gamma (IFN-c), is a homodimeric protein, which is a potent pro-inflamma- tory cytokines mainly produced by immune cells such as natural killer cells, Th1 cells and CTL, and non- hematopoietic tissue cells such as keratinocytes after activation (4, 5). IFN-c serves important functions in both of innate and adaptive immunity including cell- mediated immunity (5, 6). IFN-c which is regarded as the signature cytokine of Th1 cells has been extensively studied in several chronic inflammatory autoimmune diseases including psoriasis (7, 8), rheumatoid arthritis (9), chronic inflammatory bowel disease (10), and type 1 diabetes (11). Although various cytokines are simulta- neously generated in OLP lesions, IFN-c has implicated to have a pivotal role in the development and progres- sion of OLP (2, 3). IFN-c transcriptions were observed within the infiltrating cells and keratinocytes in the OLP lesions by in situ hybridization techniques (4, 12). By enzyme-linked immunospot assay, a portion of IFN-c producing cells were detected in the infiltrating mono- nuclear cells and peripheral blood mononuclear cells (PBMC) from the patients with OLP (13). Consistently, IFN-c was detectable in the mononuclear cells of OLP lesions using immunohistochemistry (14). Recently, Tao et al. (15) reported that the erythematous or ulcerated OLP patients had remarkably higher levels of IFN-c in lesions and whole saliva than the controls. Furthermore, immunogenetic studies have shown that Correspondence: Pornpan Youngnak-Piboonratanakit, DDS, MS (Oral Medicine), PhD (Oral Surgery), Department of Oral Medicine, Faculty of Dentistry, Chulalongkorn University, Bangkok 10330, Thailand. Tel: +6622188942, Fax: +6622188941, E-mail: pornpan. p@chula.ac.th Accepted for publication May 27, 2009 doi: 10.1111/j.1600-0714.2009.00805.x J Oral Pathol Med (2009) 38: 689–694 ª 2009 John Wiley & Sons A/S Æ All rights reserved interscience.wiley.com/journal/jop Journal of Oral Pathology & Medicine