Langerhans' cell population studies with OKT6 and HLA-DR monoclonal antibodies in vitiligo patients treated with oral phenylalanine loading and UVA irradiation.

In vitiligo patients, treated with oral phenylalanine loading combined with UVA irradiation (Phe-UVA), Langerhans' cells (LC) were counted in pigmented and depigmented skin. The LC, which were labelled with OKT6 and HLA-DR monoclonal antibodies, were expressed per linear mm epidermis. Before treatment the number of OKT6(+) cells was significantly increased in vitiliginous skin especially in the basal layer. Under treatment the number went down and was comparable to normal skin. When using HLA-DR labelling the number of LC increased in vitiliginous skin which had been treated with Phe-UVA. The influence of Phe-UVA on the shift of LC subpopulations is discussed.