although many classic (including dendritic cells and neutrophils) and non-classic immune cells (such as keratinocytes) are involved in disease pathogenesis. Communication between these cells happens mainly through cytokines such as TNFα, IFN-γ, IL-17, and IL-22, and through activation of keratinocytes, driving epidermal hyperproliferation and production of antimicrobial proteins, growth factors, and chemokines. These factors promote the characteristic changes in psoriasis including angiogenesis, neutrophil infiltration, and increased numbers of helper T cells