Skin ageing and immune competence

Ageing is associated with impairment of immune function, the most significant changes being a decrease in T-cell-mediated immunity and antibody-mediated effector functions, and an increase in autoantibodies and other dysregulatory phenomena, such as an abnormal production of monoclonal antibodies and other immune complexes. Elderly subjects are increasingly susceptible to cutaneous pathological changes that are known to correlate with immune deficiencies, such as viral and fungal infections, and skin cancers. Antigenic responses in skin may be an indicator of immune status. The recall antigens elicit fewer delayed-type hypersensitivity reactions in the elderly, particularly in subjects over 75 years old. Sensitivity to contact allergens, such as dinitrochlorobenzene, and inflammatory responses and the cutaneous response to histamine are reduced in the elderly. The pathophysiology of deficiencies in the skin's immune system in the elderly is not clear; it probably reflects not only a general decline in the immune system but also more specific changes. Age-related changes in epidermal immune functions have been observed, such as morphological and functional changes in Langerhans cells and decreased production of various cytokines. Evaluation of these changes is difficult and the results may be disputed, but it is probable that sun-induced ageing plays an important role. Few substances seem to be capable of stimulating the immunoactive cells of the skin or of modifying the production of epidermal cytokines. One possibility may be vitamin A and its derivatives, and studies of other molecules such as interferons are being carried out.