In alopecia areata, in the case of the insufficient activity of immunosuppressive molecules, proinflammatory cytokines including substance P and Interferon-gamma (IFN-γ) induce the ectopic expression of MHC class antigens and the over-expression of adhesion molecules in hair follicle keratinocytes and dermal papilla cells [13]. This evidence concerns the gene IFNG and alopecia areata.