Terminal differentiation of facial epidermis of the aged: immunohistochemical studies.

In old age, the epidermis tends to become dry and flaky, especially on the lower legs. However, this does not occur on the face, although long-term ultraviolet light irradiation has important effects on the differentiation of facial keratinocytes. Therefore, the differentiation of the epidermal cells of the facial skin in the young and the aged was immunohistochemically examined using antibodies against four differentiation products: filaggrin, involucrin, cystatin A (CTA) and carbonic anhydrase-like protein. The results showed that there was no difference in the amounts of the above three proteins in facial skin between the young and the aged with the exception of CTA. The amount of CTA was much greater in the facial skin of the aged. However, there was a striking decrease of filaggrin content in the skin of the lower leg in the aged. One of the reasons why no scaly skin is found on the face in the aged may be the fact that especially filaggrin does not decrease with aging.