To determine whether low mannose binding lectin (MBL) is associated with poor prognosis in rheumatoid arthritis (RA) and whether patients with RA have increased frequency of MBL deficiency.
Patients with recent onset symmetric polyarthritis (< 1 year, median 3 mo) were recruited if they had not been treated longer than 2 weeks with disease modifying drugs. They were reevaluated after 6 months and their disease activity and progression were correlated with their MBL concentration, rheumatoid factor (RF) isotypes, and C-reactive protein (CRP). Sixty-three female patients with advanced RA were also analyzed.
Sixty-five patients with early arthritis fulfilled American College of Rheumatology criteria for RA and 52 were followed for 6 months or longer. Low MBL was associated with raised RF, IgA RF in particular (p = 0.02). and also with a combined elevation of IgM and IgA RF (p = 0.035). Patients with low MBL (lowest 25th percentile) showed less improvement after 6 months of treatment than patients in the highest MBL quartile. This applied to the Thompson joint score (p = 0.03) and grip strength (p = 0.004). Low MBL was also significantly associated with radiological joint erosions at recruitment and at 6 month followup (p = 0.039); and the group with advanced RA also showed a significant association between low MBL concentration and radiological damage (p = 0.036). However. neither patient group had increased frequency of MBL deficiency compared to healthy controls.
Low MBL predicts poor prognosis in patients with early RA.