S‐100 immunolabelling of Langerhans cells in oral epithelium

Langerhans cells (LCs) are dendritic cells usually present in the suprabasal regions of squamous epithelia remarkable by the presence of Fc IgG and C3 receptors, Ia/Dr, T-6 and T-4 antigens on their membranes. Conventional and immunohistochemical techniques for identification of LCs require special fixation procedures and are incompatible with paraffin embedding. A method for staining LCs, in routine fixed and paraffin-embedded material, based on the use of antiserum against S-100 proteins is presented. The problem arising from the simultaneous staining of melanocytes is discussed. S-100 positive dendritic cells should be considered as LCs when fulfilling 3 criteria: located in the suprabasal layers of the epithelium; the whole cell body being visible; with at least one dendritic process.