Effects of PUVA and mechlorethamine treatment of psoriatic patients on epidermal Langerhans' cells.

Using OKT6 monoclonal antibody, we investigated the number of epidermal Langerhans' cells (LCs) in involved skin from patients with psoriasis, before and after mechlorethamine (HN2) or PUVA treatment. The number of LCs remained at about pretreatment number during three weeks of HN2 treatment alone, though they were reduced after 10 systemic PUVA treatments. Therefore, in contrast to PUVA which influences LCs, HN2 seems to have little effect on LCs. LCs in psoriatic plaques were, in number, 3-4 times less numerous than those in uninvolved, nontreated epidermis.