EFFECT OF TOPICAL TRETINOIN ON EPIDERMAL LANGERHANS CELLS IN PHOTODAMAGED SKIN

Background. Topical tretinoin has been successfully applied to treat p hotoaging; however, a decrease in the number of Langerhans' cells (Lc) has been reported after its topical application in Macaque skin. A st udy was performed to evaluate the possible effect of topical tretinoin on the number of LC in human beings. Methods. Eight patients were stu died. Topical tretinoin was applied in progressively increasing concen trations: 0.025% for 1 month, 0.05% for one month and 0.1% for 4 month s. A skin biopsy from the malar area was taken before this therapy and 6 months later. To study Lc, 4 mu frozen sections were stained with t he anti-CD1 antibody. Results, The number of CD1+ cells did not change when they were counted per unit of epidermal length, but they decreas ed when they were counted per unit of epidermal surface. Conclusions. These results indicate that topical tretinoin might damage epidermal L angerhans' cells, when it is applied for long periods of time; future studies are necessary to clarify this point.