B cells are known to play an important role in auto-immune diseases by activating T cells, secreting inflammatory cytokines and autoreactive antibodies. However, a sub-type of B cells named regulatory B cells or Bregs has recently shown capacities to prevent or cure arthritis in mouse models. Bregs have also been identified in humans. Main objective: To study Bregs abnormalities in patients with rheumatoid arthritis (RA) at different stages of the disease compared to subjects with mechanical pathologies.Secondary objectives:- To evaluate the specificity of any abnormalities identified in RA by studying Bregs in patients with other autoimmune or other inflammatory joint diseases.- To evaluate the effect of biological and synthetic treatments on Bregs in patients with RA. - To assess whether the rate of Bregs before treatment is predictive of response to biological and synthetic treatments.
