To define the roles of T cell subclusters in OLP, we sub-clustered the T cells and identified 7 cell subtypes in NEOLP, EOLP and HC: cytotoxic CD8+ T cells (IL2, GZMA, GNLY), exhausted CD8+ cells (LAG3, TIGIT, PDCD1), naïve memory CD4+ T cells (CD4, TCF7, SELL, LEF1), naïve memory CD8+ T cells (TCF7, SELL, LEF1, GZMK), NKT cells (KLRD1, KLRF1,TRDC), proliferation (MKI67, CDK1, STMN1), Treg (IL2RA, FOXP3, IKZF2) (Figure 1D). This evidence concerns the gene PDCD1 and oral lichen planus.