Title: Distribution of T-zone histiocytes in the jaw cysts.
Abstract: In order to investigate the potential role of the cell-mediated immune system in jaw cysts, the presence and distribution of T-zone histiocytes (Langerhans cells and indeterminate cells) were studied immunohistochemically using antisera to S-100 protein in the walls of six different groups of jaw cysts in relation to the degree of inflammatory cell infiltration (macrophages, MT-1 positive lymphocytes, MB-1 positive lymphocytes, plasma cells and neutrophils) and the thickness and type of covering epithelium. Materials consisted of 42 radicular cysts, 19 odontogenic keratocysts, 9 dentigerous cysts, 8 postoperative maxillary cysts, 7 nasopalatine duct cysts and 7 cysts of unknown diagnosis. Twenty samples of oral mucosa served as control.In contrast to 95% in the control oral mucosa, intraepithelial T-zone histiocytes were found in only 37% of 75 cysts having epithelial lining. The value in the supporting connective tissue was 74% and T-zone histiocytes were found more often in cysts with inflammatory cell infiltration. The mean numbers of T-zone histiocytes in a given field of the connective tissue for radicular cysts, odontogenic keratocysts, dentigerous cysts, postoperative maxillary cysts, nasopalatine duct cysts, cysts of unknown diagnosis and oral mucosa were 1.2, 1.2, 4.9, 0.2, 1.3, 2.6 and 2.5, respectively. A tendency to decreased T-zone histiocytes was observed in radicular cysts with little to very mild or severe inflammatory cell infiltration, but like in oral mucosa, the number in the odontogenic keratocyst-dentigerous cyst group was related to that of inflammatory cells, whereas there was no such correlation in the postoperative maxillary cyst-nasopalatine duct cyst group. A significant correlation was also observed between the number of T-zone histiocytes and the thickness of the covering epithelium in all cysts but those of unknown diagnosis. In addition to the thickness of covering epithelium, MT-1 and MB-1 positive lymphocytes were the factors related to the number of T-zone histiocytes in radicular cysts and odontogenic keratocyst-dentigerous cyst group in the multiple regression analysis.In conclusion, T-zone histiocytes were found to be contributing in the induction of immune response in the presence of adequate inflammation except when it is too mild or too severe to cause extensive damage of cyst wall tissues. However, further study is needed to clarify their contribution in cysts with epithelial lining of respiratory origin.