To address this gap, our study focuses directly on key lymphocyte-mediated processes, including CD4+ and CD8+ T cell activation, TNF-α and IFN-γ secretion, and the expression of cytotoxic mediators such as Perforin and Granzyme B. These core immune markers are relevant to both OLP and oGVHD. This evidence concerns the gene PRF1 and oral lichen planus.