Keratinocytes from chronic inflammatory pathologies such as psoriasis have intrinsic defects that cause exaggerated production of chemokines such as IL-8, MVCp-1, or CXCL10 and alterations in the production of IL-6, while in contact dermatitis keratinocytes overexpress IL-6, RANTES, IL-8, MCP-1, IL-1α, IL-1β, IL18, and TNF-α [37,62,63]. This evidence concerns the gene IL18 and contact dermatitis.