First, this study will evaluate, in vitro, the cellular composition of the synovial fluid from patient with rheumatoid arthritis, gout or osteoarthritis.

Then samples will be test with a new format of bispecific antibody targeting dendritic cells. The production of IL-10 will be the principal criteria of judgment. Production of others cytokines like IL-1B, IL-6, IL-12 and IFN will be checked as well.

Rheumatoid arthritis (RA) is one of the most common autoimmune disease in adult. It exists several drugs but none target dendritic cells even if it seems they play a major role in the physiopathology.

One of the unit of research of Tours recently develop a new format of bispecific antibody which target dendritic cells. The first results in PBMC (unpublished yet) show an increase of the production of IL-10 In this study, we are going to first evaluate the cellular composition of synovial fluid from patients with RA and patients with gout (for the comparison, because the inflammatory mechanisms are different) and with osteoarthritis (comparison with a non inflammatory disease) Then, we will use this new antibody and evaluate the response by dosing Il-10, IL-6, IL-12, IL1B and IFNy The aim is to verify in vitro if, with this new drug, it is possible to reverse the inflammation and induce a tolerance.

Inclusion Criteria:

• Male or female over 18 years old
• Proven and possible RA or Gout or osteoarthritis
• Arthritis accessible to a puncture
• Necessary puncture for diagnosis or therapeutic

Exclusion Criteria:

• Microcrystalline rheumatism other than Gout
• Known SpA
• Septic arthritis
• Biomedicament treatment
• Patient having objected to the processing of his data

Patients with acute arthritis of RA or Gout or with osteoarthritis. Puncture necessary for daily practice (diagnostic or therapeutic)