The key player leading to inflammatory responses and tissue damage in these diseases is IFN- γ by increasing the sensitivity of keratinocytes (KCs) and cytotoxic T lymphocytes activation through enhancing major histocompatibility (MHC) class I expression, and upregulating DCs MHC class II expression which helps the antigen presentation to CD4 + T-cells, while TNF-α cytokine acts in synergism with IFN-γ on the destruction of KCs and melanocytes [28–30]. Here, CD4 is linked to dry eye syndrome.