Clonal expansion of lymphocytes from oral lichen planus lesions.

Lymphocytes were extracted from 11 biopsy specimens of oral lichen planus (OLP) by collagenase digestion, and cell lines were expanded with repetitive cycles of stimulation (with phytohaemagglutinin) and rest in media supplemented with interleukin 2. Four OLP lines contained a majority of CD3+CD4-CD8+ cells, in six lines the CD4:CD8 ratio was between 1 and 2, and in one line the CD4:CD8 ratio was 5:1. Limiting dilution of nine lines at 0.3 and 1.0 cells/well resulted in viable wells (putative clones) with plating efficiencies ranging from 0.0 to 18.1 percent and 0.0 to 22.2 percent respectively. The majority of clones were CD3+CD4-CD8+alpha beta+gamma delta-, although three clones were CD3+CD4+CD8-alpha beta+gamma delta- and one clone was CD3+CD4-CD8- and expressed the gamma delta T cell receptor. T cell clones derived from lymphocytes extracted from OLP lesions may be generated and maintained in culture providing opportunity for their further phenotypic and functional characterisation. This strategy may facilitate the identification of a putative oral lichen planus-specific antigen and indicate the frequency of lichen planus-specific T cells within lesions of OLP.