Soluble Tim3 detection by time-resolved fluorescence immunoassay and its application in membranous nephropathy

Abstract

Background: We aimed to develop a time-resolved fluorescence immunoassay (TRFIA) for detecting soluble T-cell immunoglobulin and mucin domain 3 (sTim3) in serum samples and to demonstrate a preliminary application of this method in membranous nephropathy (MN). Methods: sTim3 TRFIA was developed, and the sTim3 concentration in the serum of patients with MN and healthy individuals was detected using a sandwich method. Results: The sensitivity of the developed sTim3 TRFIA was 0.66 ng/mL, higher than that of an enzyme-linked immunosorbent assay (ELISA) (1.11 ng/mL). The detection range was 0.66-40 ng/mL. The intra-assay coefficient of variation (CV) for sTim3 was 1.64%-4.68%, and the inter-assay CV was 5.72%-9.32%. The cross-reactivity to interleukin 6 (IL-6) and kidney injury molecule 1 (KIM-1) was 0.25% and 0.04%, respectively. The average recovery was 105.26%. The sTim3 concentration in patients with MN was considerably higher than that in healthy individuals (P