Abstract:

[Abstract] Objective To observe changes in CD1a+ Langerhans cells and CD68+ dermal macrophages in healthy adult human skin after irradiation with solar-simulated ultraviolet. Methods Fourteen healthy Han Chinese women were recruited in the study after obtaining informed consent. An area on the non-sun-exposed back skin of each subject was irradiated by 1.5x minimum erythema dose ( MED) of ssUVR once per day for four days. A biopsy was taken from each subject 72 hours after the last irradiation and frozen sections of the biopsies were stained by ABC immunohistochemistry for CD1a and CD68. Results After ssUVR irradiation there was a significant decrease in the number of LC to 96±53/mm2 compared to 258±61/mm2 in normal control skin 72 hours post-irradiation (P < 0.001). The staining showed irregular morphology of the CD1a+ LC with shortened dendrites. After ssUVR there was a significant increase in the number of CD68+ macrophages in the dermis to 399±65/mm2 compared to 290±22/mm2 in normal control skin 72 hours post-irradiation (P < 0.001). The location of these macrophages moved up toward the epidermis and the cells showed long and inter-connecting dendrites. Conclusions ssUVR could reduce LC density in the epidermis but the dermal macrophages increased in density 72 hours after ssUVR, indicating a compensatory or inflammatory mechanism that stimulate such increase in the dermis.