CIPRIAN IOAN ROI, PUSA NELA GAJE, RALUCA AMALIA CEAUSU, RAMONA AMINA POPOVICI, MARIUS RAICA IMMUNOHISTOCHEMICAL ANALYSIS OF S100-POSITIVE LANGERHANS CELLS IN THE HEALTHY GINGIVA AND PERIODONTAL DISEASE Langerhans cells are antigen presenting cells, located in the stratified squamous epithelium of the skin and oral epithelium. A high density of Langerhans cells in gingival epithelium associated with an inflammatory process has been demonstrated in the literature by numerous studies, although the relationship with inflammation was less investigated.The aim of our study was to evaluate the distribution, density, morphology of Langerhans cells in both gingival epithelium and the associated inflammatory infiltrate in the lamina propria of the gingiva. The relationship between Langerhans cells and inflamatory process was also assesed. The present study included a number of 51 gingival biopsies. 12 of these didn’ t show significant changes on routine examination. In all of the other 39 cases the presence of inflammatory lesions was noticed. The inflamatory infiltrate was described by using hematoxylin eosin staining and quantitative score, with values between 0 and 3. Langerhans cells were immunohistochemicaly highlighted by using S100 antibody and quantified with hot spot method.We found an increase of Langerhans cells density in all cases of inflammation as compared with healthy gingival tissue. The highest density was found in the 13 cases with severe inflammation. At these last cases was noticed a migration tendency of Langerhans cells from infiltrate inflamatory area to basal layer of the epithelium. The results of this study indicated that Langerhans cells number is higher in inflamatory gingival tissue comparative with normal tissue, and the density of these cells is in relation with the severity of the inflammatory process.