Here, the antigen-specific mechanisms comprised of activation of T-cells subsequent to antigen presentation and basal keratinocytes apoptosis triggered by CD8+ cytotoxic T cells, while non-specific mechanisms involve over-expression of matrix metalloproteinases (MMPs) and degranulation of mast cell in OLP lesions [181,182,183,188]. The gene discussed is CD8A; the disease is oral lichen planus.