Free light chains of immunoglobulins in serum as biomarker of activity in systemic lupus erythematosus
Abstract
OBJECTIVE: To explore the changes of serum concentration on of FLC kappa and FLC lambda as putative biomarkers of SLE disease activity in a prospective, comparative, and cross-over study.METHODS:Eighty-three adult SLE (ACR/1982, update in 1997) patients and 33 age- and sex-matched healthy controls were enrolled; concomitant infection, monoclonal gammopathy and renal failure in patients under study were excluded. Disease activity was assessed using the Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K): a score ≥6 was considered clinically important.FLC kappa and FLC lambda in serum were analysed by quantitative nephelometric assay and compared against SLEDAI-2K and serological biomarkers IgG,C3,C4,"total" ANA, anti-dsDNA, and antinucleosome Abs.
Statistical analysis using Medcalc-Statistical software programme was made. RESULTS:FLC (kappa, lambda and total) concentration in serum correlate strongly with disease activity in SLE and is significantly higher in patients with clinically important SLEDAI-2K≥6; these results are suggesting that serum FLC may be used as biomarker of SLE disease activity.