CD4 and oral lichen planus: DCs in OLP can present antigens to CD4+ T cells, and their secreted interleukin-12 (IL-12) induces cytokine release from CD4+ T cells, including interferon gamma (IFN-γ) and IL-2, recruits CD8+ T cells to subepithelial regions and activates CD8+ T cells, eventually leading to the onset of chronic inflammation (43–45).