Characterization of the Effect of Tocilizumab in Vivo and in Vitro on T Follicular Helper Cells in Rheumatoid Arthritis Patients and Consequence on B Cells Maturation

Inclusion Criteria

• •Inclusion in TCZ and MTX groups:
• •Patients with active moderate to severe RA fulfilling ACR criteria and requiring TCZ or MTX treatment, according to the EU label and French authority recommendations, who accept to enter the study and to sign the informed consent.
• •Patients \> 18 years
• •When treated with corticosteroids: Dose ≤10mg/jour within 4 weeks before inclusion and dose stable during the study.
• •When treated with MTX (0.3 mg/kg/w): Dose stable within 4 weeks before inclusion and during the study to avoid confusion on Tfh levels evaluation.
• •When treated by prior anti-TNF: according to the recommendations of the French "Club Rhumatismes Inflammatoires", a wash-out period of 5 half-lives will be defined to avoid confusion in the evaluation of Tfh cells initial levels.
• •These patients will be consecutively included in the study until the number of needed patients will be reached.
• •Inclusion in the healthy controls group:
• •Healthy controls will be defined as people non-affected by an inflammatory disease (such as RA, ankylosing spondylitis, lupus…). This group will be constituted with patients affected by sciatica, osteoarthritis, osteoporosis…
• •These patients will be included in a second phase in order to guarantee the quality of matching with cases.