The efficacy of TNF alfa inhibitors in the treatment of psoriasis has been documented in many studies.||Their effect on dendritic cells has been scarcely studied. TNF- α has a central role in dendritic cell biology, both for their maturity and mobilization of peripheral tissues to secondary lymphoid organs.||The primary objectives of this study are:||To document absolute number, density of immune infiltrate and dendritic cells and inflammatory cytokines expression pattern (particularly IFN α and IL-32) in psoriasic lesions vs normal skin of the same patient|To describe changes in such cell numbers and expression patterns upon 16 weeks treatment with TNF alfa inhibitors.