The Inventors have developed an ELISA of a new molecular marker detecting a neoepitope generated from the cleavage of the α1 chain of type III collagen within its helical domain. Serum levels of this marker were significantly increased in patients with RA and is significantly associated to CRP and ESR levels. Indeed, they demonstrated that the median serum HELIX-III levels were significantly higher in patients with moderate (p=0027) and active RA (p=00004) compared with those in age-matched controls.
The present invention relates to an antibody recognizing an epitope having SEQ ID NO :1 of collagen protein and its uses for diagnostic, prognostic and monitoring purposes.