The effect of aging and chronic sun exposure on human Langerhans cell populations.

ATPase histochemistry was used to examine Langerhans cell (LC) populations in the skin of young persons with no evidence of solar damage and older adults with chronic actinically damaged skin. The number of LC was significantly decreased in the older age group. Significantly fewer LC were observed in exposed vs covered skin in the older individuals; no such disparity was noted in the younger subjects. Morphologic alterations in ATPase-positive cells were noted in some specimens, most of which were taken from the exposed skin of elderly persons. The results suggest an independent, although possibly additive, quantitative and qualitative influence of aging and chronic sun exposure on the LC population. Decreased numbers of LC in the sun-damaged skin of elderly individuals may play a critical permissive role in the development of cutaneous carcinoma.