Elevation of Immunoglobulin Free Light Chain and BAFF Levels Associated With Immune Activation Predicts Survival Rates in Chronic Liver Disease.

Aims: Elevated serum free light chain (FLC) and B-cell activating factor (BAFF) levels have been reported to be associated with B-cell activation and to serve as biomarkers reflecting disease severity in various diseases. However, limited investigation has been conducted in the context of chronic liver disease (CLD), and the aim of this study was to clarify the clinical utility of FLC and BAFF in CLD.

Methods: Serum FLC and BAFF levels were measured in healthy individuals (HC; n = 23) and in a cohort of patients with chronic hepatitis (CH; n = 107) and liver cirrhosis (LC; n = 50) of various etiologies and the associations of κ-FLC, λ-FLC, or BAFF with liver function test results and survival rates were investigated.

Results: Serum FLC and BAFF levels increased in parallel with a decrease in hepatic functional reserve capacity, worsening fibrosis, and impaired renal function. Serum κ-FLC, λ-FLC, or BAFF levels were significantly elevated in CH compared to HC (p < 0.05, p < 0.001, respectively) and further increased in LC (p < 0.0001 vs. both HC and CH). The survival rate was significantly lower in patients with high κ-FLC, λ-FLC, or BAFF compared with patients with low κ-FLC, λ-FLC, or BAFF (p < 0.0001, p < 0.01, respectively). Even in the analysis using the multivariable Cox proportional hazards model, both κ-FLC and λ-FLC were identified as independent prognostic factors.

Conclusion: This study specifically demonstrated that serum FLC levels are a strong predictor of survival in patients with CLD and provided important insights into the prognosis of CLD in the context of humoral immunity.