Imbalance in phenotypic expression of T cell subpopulations during different evolutional stages of lichen planus lesions.

Immunoenzymatic (in light and in electron microscopy) and immunofluorescence techniques were performed, using monoclonal antibodies, on tissue sections of early lichen planus (LP) lesions versus late LP lesions from 20 patients. Control procedures were carried out in peripheral blood T cells from the same patients and from healthy donors. The OKT4-Leu3A/OKT8-Leu2A ratio in peripheral blood from LP patients and from donors was lower than in dermal infiltrate of early LP lesions, but higher than in dermal infiltrate of late LP lesions. It is conceivable that in early LP lesions OKT4-Leu3A-positive cells may be antigen-specifically 'educated' by immunostimulatory cells. In late LP lesions, OKT8-Leu2A-positive cells could be cytotoxic to keratinocytes; it is likely, however, that this latter population may moreover have immunoregulatory, resolutional functions.