The synovial levels of this chemokine correlate with the serum CXCL13 accumulation in RA patients (34, 35).The CXCL13 appears to be a marker of disease severity in RA, so that a prospective study reported that patients with RA in the early onset of the disease with the highest serum level of CXCL13 had the highest rate of progression of joint damage in long-term follow-up (32, 36). This evidence concerns the gene CXCL13 and rheumatoid arthritis.