Electron-microscopic and immunohistochemical studies of Langerhans cells and Thy-1-positive cells in mouse tongue epithelium subjected to local hyperthermia.

Local hyperthermia via skin has been used to treat cancer but may suppress local immune responses as a side-effect. To examine effects of heat on immunologically responsive cells in oral mucosa, mouse tongues were heated by an implant system at 43 degrees C for 20 min. The densities of Langerhans cells and Thy-1-positive cells rapidly increased within 3 h after the treatment, then returned to a normal level after 7 days. Electron microscopy confirmed that Langerhans cells in the tongue epithelium formed clusters with lymphocytic cells, suggesting an active response to the hyperthermia.