Immunophenotyping of the dermal cell infiltrate in lichen planus treated with PUVA.

To evaluate the immunoregulatory mechanisms in lichen planus (LP) responding to PUVA therapy, the LP skin lesions of eight patients were biopsied before and after treatment with trioxsalen baths and UVA. The percentages of B, T, and MPS (monocyte-macrophage) cells as well as OKT-4+ (helper) and OKT-8+ (suppressor) T cells were calculated. OKT-8+ T cells were the dominating cell type in untreated LP lesions. Following PUVA therapy, the percentage of OKT-8+ T cells decreased very significantly (p less than 0.001) as did also the number of MPS cells. These results suggest that cell-mediated immune mechanisms are involved in the pathogenesis of LP, and T suppressor cells most probably participate in evolvement of the typical LP lesions. T suppressor cells in the LP lesions are reduced after local PUVA therapy, occurring simultaneously with complete healing of the affected skin.