Assessment of serum free light chains in patients with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by loss of B cell tolerance to self antigens resulting in the production of a wide variety of auto antibodies. The objective of this study was the assessment of serum free light chains (FLC) assay in patients with SLE. In this study, 156 patients (142 women and 14 men, mean age 35.6 years) and 60 healthy subjects (55 women and 5 men, mean age 36.4 years) were included. The kappa (κ) and lambda (λ) FLC were measured by turbidimetry method. The analysis of our results showed that the FLC rates κ and λ were significantly higher in patients compared to controls (44.52 vs. 8,55 mg/L, P = 0.0001 for FLC κ and 33.43 vs. 12,99 mg/L, P = 0.0001 for FLC λ). In addition, significant associations were noted between the increase in FLC κ, λ and disease activity (P = 0.006 and P = 0.008 respectively), as well as with the presence of lupus nephritis (P = 0.044 and p = 0.045). The increase of the serum FLC during SLE could be a useful marker for assessing the disease activity and the risk of lupus nephritis.