Epidermal Langerhans' cells in chronic eczematous dermatitis of the palms treated with PUVA and UVB.

Epidermal Langerhans' cells (LC) were studied in patients with chronic eczematous dermatitis of the palms. The monoclonal antibodies anti-Leu 6 and anti-HLA-DR were used, and the cells visualized with an immunoperoxidase technique. Increased numbers of LC were found in allergic contact dermatitis as well as in irritant contact dermatitis and hyperkeratotic dermatitis of the palms. The increased number of epidermal LC in lesional skin may facilitate presentation of exogenous or endogenous antigens to activated T-cells. One hand was treated with PUVA or UVB and the other hand served as a non-exposed control. PUVA treatment cleared the dermatitis and the LC number decreased markedly. With UVB treatment clinical improvement was achieved, and a less pronounced decrease in epidermal LC was noticed. There seems to be a crude relationship between the extent of clinical improvement and the reduction in epidermal LC numbers. The change in LC might be a primary event or secondary to a reduction of the inflammatory process.