DETECTION OF T-LYMPHOCYTES AND T-LYMPHOCYTE SUBSETS IN LICHEN-PLANUS - IN-SITU AND IN PERIPHERAL-BLOOD

Background. Abnormal immune mechanisms are thought to be important in the pathogenesis of lichen planus (LP). This is a study to clarify the changes that occur in T lymphocytes and T lymphocyte subsets, both in situ and in peripheral blood. Methods. A group of 100 patients with L P were included in this study. T lymphocytes and T lymphocyte subsets were detected in lesional skin by immunoperoxidase cell surface staini ng using monoclonal antibodies. Peripheral T lymphocytes and T lymphoc yte subsets were also detected by indirect immunofluorescence using mo noclonal antibodies. A group of 10 normal healthy subjects were used a s controls. Results. The study of the lesional T lymphocytes and T lym phocyte subsets demonstrated that helper T cells was the predominant s ubset in LP lesions in most of the patients. This predominance was evi dent irrespective of the duration of the disease and was more evident in late than in early lesions. The percentage of both total T lymphocy tes and helper T cells in peripheral blood was decreased significantly in patients compared with controls. A significant decrease in helper T cells and the helper/cytotoxic T cell ratio was detected in patients with a longer duration of the disease. Conclusion. Activation of help er T lymphocytes that were found to be the predominant subsets in LP l esions may be responsible for epidermotropic cellular infiltrates lead ing to damage and destruction of epidermal cells.