Leukocyte Cell-Derived Chemotaxin 2 (LECT2) is a multifunctional protein primarily secreted by hepatocytes, with additional expression in immune cells and endothelial cells. First identified as a chemotactic factor that recruits neutrophils, it is now recognized to exert broader roles across diverse physiological and pathological processes—including liver regeneration, angiogenesis, osteoblastogenesis, and metabolic regulation. Functioning as a cytokine-like signaling molecule, LECT2 can bind to specific receptors (e.g., CD209a) to modulate immune responses. Besides,Alpha-1-Antitrypsin (a1AT) has been identified as an interactor of LECT2, thus a functional binding ELISA assay was conducted to detect the interaction of recombinant rat LECT2 and recombinant human a1AT. Briefly, a1AT was diluted serially in PBS with 0.01% BSA (pH 7.4). Duplicate samples of 100 μl were then transferred to LECT2-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST and incubated for 1h with anti-a1AT pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody for 1h at 37℃, wells were aspirated and washed 5 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37℃. Finally, add 50 µL stop solution to the wells and read at 450/630nm immediately. Measured by its binding ability in a functional ELISA. When Recombinant LECT2 is lmmobilized at 2 µg/mL(100 uLwell), the concentration of a1AT that produces 50% optimal bindingresponse is found to be approximately 0.073 µg/mL.