Used to quantitatively measure soluble LAG-3 (lymphocyte activation gene-3) in human serum, plasma, or cell culture samples. This ELISA kit helps researchers study immune regulation, particularly in cancer immunotherapy, autoimmune diseases, and infectious diseases. LAG-3 is a checkpoint receptor involved in suppressing T-cell activation, making it a key target in understanding immune exhaustion and response to therapy. The kit enables accurate detection of LAG-3 protein levels, supporting biomarker development and evaluation of therapeutic interventions targeting the LAG-3 pathway.