Non-dendritic Langerhans cells: A new entity in normal and malignant buccal mucosa

Langerhans cells (LCs) are the most effective antigen presenting cells against foreign bodies and carcinogens. Since the oral cavity is a portal of entry for these antigens, the aim of this study was to morphologically classify CD1a+ LCs, quantify them in the normal and malignant buccal mucosa, and evaluate their relation to the age of patients. Healthy buccal mucosal samples collected from 16 patients undergoing reconstructive operation, and malignant samples obtained from 15 patients undergoing radical oncological resection. were processed for immunohistochemistry four- to five-micron thick sections were stained with CD1a antibody (CD1a). At 40X magnification, CD1a+ LCs were morphologically classified and quantified manually for a 25mm length of basement membrane using Cellsens image analysing software and the data was analysed. Two categories of CD1a+ LCs were identified in the normal and malignant buccal mucosa a) typical dendritic LCs and b) non-dendritic LCs (a new entity). Non-dendritic LCs were of significantly higher number compared to the typical dendritic LCs in the normal tissues (p -0.001). In the malignant group, the non-dendritic CD1a+ LCs were significantly fewer in number (p-0.004), when compared to the normal group. Non-dendritic LCs were also significantly fewer (p-0.026) in patients over 60 years of age. This is the first report of non-dendritic Langerhans cells in normal buccal mucosa and malignant buccal mucosa using the CD1a marker. The significantly higher number of these cells in normal tissues and younger individuals supports their role as accessory antigen presenting cells.