T cell receptor V-gene usage in oral lichen planus; increased frequency of T cell receptors expressing V alpha 2 and V beta 3.

In order to analyse the clonality of T cells in the inflammatory infiltrate of oral lichen planus (OLP), mucosal biopsies were obtained from seven patients with manifest disease. The biopsies were stained with MoAbs directed against 11 different T cell receptor (TCR) V-gene families, anti-CD4, anti-CD8 and IL-2 receptor (IL-2R). For comparison, the frequencies of the different TCR V-families were determined in biopsies from five patients with oral candidosis as well as in peripheral blood from three patients with OLP and from six healthy blood donors (HBD). The occurrence of the investigated TCR V-families varied between 0% and 7% in venous blood obtained from both HBD and OLP patients. T lymphocytes expressing the TCR V beta 3 and V alpha 2 in OLP biopsies were, however, detected in frequencies ranging between 18% and 40% of the total fraction of lymphocytes, a consistent finding for all the OLP infiltrates studied. The other nine TCR V-families examined appeared in low frequencies both in biopsies and in peripheral blood. V alpha 2+ and V beta 3+ cells were often localized adjacent to the basal membrane. In contrast, T cells in Candida-induced lesions did not express a biased TCR distribution, and most V-families studied appeared in frequencies of 0-6%. Thus, T lymphocytes in OLP lesions express a substantially higher frequency of TCR V alpha 2 and V beta 3 than expected from the distribution in blood. The clonal expansion of T cells observed in OLP suggests that a superantigen is involved in the pathogenesis of the disease. Whether this superantigen is of exogenous or endogenous origin needs to be investigated.