Accumulation of oligoclonal T cells in the infiltrating lymphocytes in oral lichen planus

Background: Identification of a disease-specific and possibly pathogenic T-cell receptor (TCR) in oral lichen planus (OLP) is one of the most important steps to reveal the pathogenic antigen recognized by the T cells and thereby elucidate the pathogenesis and etiology of OLP. Methods: In buccal mucosa biopsy specimens and peripheral blood mononuclear cells (PBMC) from seven patients with OLP, the TCR Vβ gene usage was examined by polymerase chain reaction-based and single-strand conformation polymorphism analyses. Results: The Vβ families expressed in the biopsy specimens were markedly heterogeneous, but they were restricted in comparison to those observed in the PBMC. The Vβ families predominantly expressed in the biopsy specimens in comparison with the PBMC were still heterogeneous in individual patients and differed from patient to patient; however, Vβ2, Vβ6, and Vβ19 were commonly predominant in the biopsy specimens from more than half of the patients. Among the Vβ families predominantly expressed in the biopsy specimens, the accumulation of T-cell clonotypes was observed in the majority of the Vβ families including Vβ6 and Vβ19; however, it was not observed in the minority of the Vβ families including Vβ2. Conclusions: These results suggest that unique T-cell populations bearing Vβ2, Vβ6, or Vβ19 gene products tend to expand in OLP lesions as a consequence of in situ stimulation with a restricted epitope of either a nominal antigen on the MHC molecule for the majority of the Vβ families, even if only in minor populations, or of a common superantigen for the minority of the Vβ families.