However, in persistent tissue damage and cellular growth, the infection-fighting agents may play a dangerous role due to the production in DNA-related mutagenic factors which cause alterations in epithelial and stroma cell proliferation; in addition, macrophages and T-lymphocytes may secrete tumor necrosis factor-alpha (TNF-α) and macrophage migration inhibitory factors that are involved in DNA alterations [21]. Here, TNF is linked to infection.