The expertise in the characterization of transcriptomics profile in lesional psoriatic skin and on the availability of innovative therapy for these patients.The investigators propose to follow the modification of the skin transcriptomics profile in psoriatic patients during successful Adalimumab biotherapy. Skin transcriptomics profiles of normal skin, psoriatic non lesional skin, and psoriatic lesional skin before and after biotherapy will be compared. The investigators will focus on the modification of the cytokine "signature" in these skin lesions and of some markers of keratinocyte inflammation. The modification of the transcriptomics profile induced by the biotherapy will be correlated to the clinical response Psoriasis Area and Severity Index.

Inclusion Criteria:

• Adults with chronic plaque psoriasis involving at least 10% of body surface area with no previous biotherapy.
• Adalimumab prescribed in usual practice

Exclusion Criteria:

• Patients presenting a contraindication to the use of Adalimumab: hypersensibility in Adalimumab or in one of the excipients.
• Patients presenting an evolutionary tuberculosis or the other severe infections such as sepsis and opportunist infections.
• Patients with one cardiac insufficiencies moderated in severe.
• Patients under anakinra or abatacept.
• Patients with a current participation in another study of clinical research.

4 months