In rheumatoid arthritis (RA) patients, infliximab therapy results in a temporary reduction in serum tenascin-C (TNC), while treatment with methotrexate (MTX) or tranilast does not. Blood was taken from RA patients at entry into their trial (week 0) and at various weekly intervals afterwards. Serum (cohort A) or plasma (cohort B) was collected and TNC levels were measured by ELISA. In cohort A patients received infliximab therapy immediately (n = 12) (A) or after 52 weeks (n = 12) (B). Arrow shows the start of infliximab therapy. In cohort B, patients received either MTX alone (C) or tranilast therapy at 75 mg/kg or 150 mg/kg (D) from week 0 (n = 9).