Different amounts of protein-bound citrulline and homocitrulline in foot joint tissues of a patient with anti-citrullinated protein antibody positive erosive rheumatoid arthritis.

Background Antibodies binding to citrullinated proteins are a frequent finding in rheumatoid arthritis patients and may precede the onset of clinical symptoms several years. The antibodies are a predisposing factor for bone erosions but their origin is unknown. In this study we analyze in detail the levels of protein bound citrulline and homocitrulline in several tissue samples of a single erosive arthritic surgery patient.