Human Fibrinogen (PAD4 Citrullinated)

Fibrinogen is a plasma clotting factor composed of three different polypeptide chains (?, ? and ?). Under chronic inflammatory conditions, fibrinogen can be acted upon by the enzyme peptidylarginine deiminase 4 (PAD4), converting specific arginine residues to citrulline. Patients with rheumatoid arthritis (RA) produce antibodies that bind citrullinated human fibrinogen.{21644} The citrullinated fibrinogen and reactive antibodies form immune complexes in RA patients, and these immune complexes can stimulate macrophages.{21645,21643} Recently, it has been discovered that immunizing certain strains of mice with citrullinated human fibrinogen can induce the production of anti-citrullinated human fibrinogen antibodies and the development of arthritis that shares many pathophysiological features of the human disease.{21646,21647}