Used in immunological research to quantify levels of galectin-9 in biological samples such as serum, plasma, and cell culture supernatants. Enables study of immune regulation, inflammation, and cancer progression due to galectin-9's role in T-cell modulation and apoptosis. Commonly applied in biomarker discovery and monitoring therapeutic responses in autoimmune diseases and oncology research. Provides high sensitivity and specificity for detecting low concentrations of galectin-9, supporting reproducible results in clinical and preclinical studies.