TNF and psoriasis: Indeed, TNF- α is a key component of the inflammatory cascade in skin (51), IL-12p40 acts as a chemoattractant for macrophages (52), IL-1RA and IL-1B are known to be upregulated during inflammatory skin conditions such as psoriasis (50) and finally GM-CSF is known to activate regenerative epidermal growth and stimulate keratinocyte proliferation (53).