The role of serum free light chain as biomarker of Myasthenia Gravis

Background and aim: Myasthenia gravis (MG) is a B lymphocyte–mediated disease affecting neuromuscular transmission. The clinical course of MG is unpredictable due to the fluctuating nature and heterogeneity of the disease. Increased levels of free light chains (FLC), which reflect B cell activation, have been detected in different autoimmune disorders. In this study, we evaluated the potential role of FLC as diagnostic and prognostic biomarkers of MG. Materials and methods: 74 MG patients and 52 healthy individuals were included in the study. Serum FLC levels were measured by turbidimetric assay (Freelite, The Binding Site Group Ltd) on the Optilite Analyser System in both groups. In MG patients, anti-AChR and anti-MuSK autoantibodies were detected by enzyme-linked immunosorbent assay. Results: MG patients displayed significantly higher serum κ and total FLC levels than controls, respectively for κFLC 16.0 vs 13.8 mg/L and for total FLC 29.8 vs 25.9 mg/L. Moreover, increased κFLC levels were observed in seropositive MG patients. No association was observed between serum FLC levels and clinical manifestations of disease as well as with severity, age at MG onset, thymoma and treatment. Conclusion: Increased levels of κFLC and total FLC could serve as biomarkers to support the diagnosis of MG.