Effects of aromatic retinoid (Ro 109359) on Langerhans' cells in lichen planus

Retinoids are used in the treatment of lichen planus (LP) disease, but their mechanism of action remains unknown. We studied the epidermal Langerhans' cells in four patients with chronic LP, before and after treatment with aromatic retinoids. This study uses a new technique of quantification and exploits two monoclonal antibodies-OKT 6 specific for Langerhans' cells and BL 2 specific for HLA-DR antigens. Our results show an increase in the number of dendritic epidermal cells after treatment with oral retinoids. The number of OKT 6-positive cells is greater than the number of BL 2-positive (HLA-DR) cells before and after treatment.