Effects of near-infrared radiation on the epidermal proliferation and cutaneous immune function in mice

While ultraviolet radiation alters various cutaneous cell functions, little is known about the photobiological effects of infrared radiation (IR) on the skin except its local thermal effect. This study demonstrated that single exposure of mouse skin to near IR (0.7-1.3 mu m) reversibly suppressed the proliferating activity of the epidermis, the density of Langerhans cells, and the ability of skin to induce contact hypersensitivity reaction. During the exposure, the ear surface temperature was elevated from a mean of 27 to 31.2 degrees C. The results suggest that near IR can modulate the epidermal proliferation and part of the skin immune system, with a mild thermal effect.