Urine free light chains as a novel biomarker of acute kidney allograft injury.

Background: We evaluated urine free light chains (FLC) as a potential biomarker for acute kidney allograft injury (AKAI).

Methods: Urine κ and λ FLC were compared with urine β-2 microglobulin (β2-M), retinol-binding protein (RBP), kidney injury molecule 1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), and microalbuminuria (MAB) in biopsy-confirmed acute rejection (AR) and acute tubular necrosis (ATN). Healthy volunteers (normal) and transplant recipients with normal allograft function (control) were used as references.