cell biochemistry and function Cell Biochem Funct 2005; 23: 181–187. Published online 17 September 2004 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1027/cbf.1138 Ultrastructural determination of gingival Langerhans cells in alloxan-induced diabetic rats Nesrin O ¨ zsoy* 1 , Nursel Gu ¨l 1 , Hamit Bostanci 2 and Cevat Ayvali 1 1 Department of Biology, Faculty of Science, Ankara University, Tandog ˇan, Ankara, Turkey 2 Department of Periodontology, School of Dentistry, AnkaraUniversity, Bes¸evler, Ankara,Turkey The ultrastructure of Langerhans cells has not been fully investigated in diabetes-associated gingival tissues. The present study was carried out to investigate the ultrastructure of gingival Langerhans cells in alloxan-induced diabetic rats. Gingival biopsies were obtained from 22 diabetic and 18 control rats. Langerhans cells were observed by transmission electron micro- scopy (TEM) in the basal layers of healthy oral epithelium. On rare occasions, Langerhans cells were found in the suprabasal layers of the oral epithelium. Langerhans cells in the oral epithelium of diabetic rats were seen in the basal and suprabasal layers. Usually, Langerhans cells had clear cytoplasm and convoluted or indented nuclei and few or no specific granules. The clear cytoplasm contained mitochondria, lysosomes and a small number of rough-surfaced endoplasmic reticulum regions, but it lacked tonofilament. Occasionally, centrioles were also observed in the cytoplasm. The membrane of Langerhans cells had no junctional complexes such as desmosomes. In diabetic rats, Langerhans cell precursors were developed into specific granule-bearing cells. Both Langerhans cells and their granules were more frequent in the gingiva of diabetic rats than in the control group. These data suggest that Langerhans cells play an important role in explaining the pathogenesis and develop- ment of diabetic gingivitis. Copyright # 2004 John Wiley & Sons, Ltd. key words — diabetes mellitus (alloxan-induced); Wistar albino rat; Langerhans cells; oral epithelium; transmission electron microscopy INTRODUCTION Langerhans cells (LCs) are dendritic bone marrow- derived cells that form a network within stratified squamous epithelia, such as the epidermis and the epithelium of oral mucosa, including the gingiva. 1–3 Langerhans cells have been identified in the skin, 4,5 uterine cervix, 6 sheep rumen, 7 and murine vagina. 8 Langerhans cells function as antigen-presenting cells and play an important role in the immune system, par- ticularly in antigen presentation to the T-lymphocytes. Moreover, they possess Fc-Ig G and complement receptors and Ia antigens. 9,10 According to many authors, these cells play an important role in the initia- tion and development of gingival inflammation. 1,11–13 Diabetes mellitus is a disease with heterogenic charac- teristics that affects all systems. Many studies suggest that diabetes mellitus affects gingival tissue and consequently these tissue changes may lead to an increased prevalence and severity of periodontal diseases. 14,15 Some studies, despite counter arguments, also suggest that the degree of gingival inflammation is much higher in diabetic rats than in non-diabetic rats. 16,17 In inflammatory and autoimmune diseases, increased numbers of Langerhans cells have been observed in the oral gingival epithelium when gingivi- tis develops as a result of experimental plaque accumu- lation. 1,4,11,18 It has been suggested that Langerhans cells may be involved in the pathogenesis of type I diabetes. 19,20 These Langerhans cells cannot be identi- fied in routine histological sections, but they can be identified by enzyme histochemistry or electron micro- scopy. The ultrastructure of Langerhans cells has not been fully investigated in diabetes-associated gingival tissues. Newcomb and Powel 21 in 1986 studied the ultrastructure of gingival Langerhans cells in patients having periodontal disease. We have focused on dia- betic gingiva. The present study was carried out to in- vestigate the ultrastructure of Langerhans cells in the gingival epithelium of alloxan-induced diabetic rats. Received 4 November 2003 Revised 8 December 2003 Copyright # 2004 John Wiley & Sons, Ltd. Accepted 17 December 2003 * Correspondence to: N. O ¨ zsoy, Department of Biology, Faculty of Science, Ankara University, Tandog ˘an, Ankara, Turkey. E-mail: ozsoy@science.ankara.edu.tr