Langerhans cells-a reduction in numbers and their reappearance following steroid and cytotoxic therapy in humans

Epidermal Langerhans cells (LC) stained by antibodies to Ia, T6 and S-100 showed sustained reduction in numbers following the application of betamethasone-17-valerate 0·05% cream to normal human skin. An initial decrease in cell numbers after 24 h reached a plateau phase after 7 days which remained until a return to almost normal cell numbers following cessation of the steroid. Epidermal Langerhans cells were also reduced in the normal skin of patients receiving cytotoxic chemotherapy for solid tissue tumours. The Langerhans cell numbers rapidly returned towards normal when the chemotherapy ceased; the increase in numbers tended to parallel the recovery in drug-induced bone marrow suppression. These findings arc further evidence in humans that bone marrow replacement may be important in the return of LC numbers following their loss by various insults. This also occurs in association with local recovery of LC which are damaged, but not lost.