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. The gene discussed is CD4; the disease is oral lichen planus.