Recombinant human interleukin‑2 (rhIL‑2) is a genetically engineered non‑glycosylated protein consisting of 133 amino acids, sharing identical biological activity with native IL‑2. As a pleiotropic cytokine central to immune regulation, IL‑2 is mainly secreted by activated CD4⁺ T cells, and also produced by CD8⁺ T cells, eosinophils, dendritic cells and thymocytes. It drives T‑cell proliferation, B‑cell activation and helper T‑cell differentiation, promotes Th1‑cell polarization and IFN‑γ secretion, and boosts glycolysis. Moreover, IL‑2 is indispensable for regulatory T‑cell differentiation and immune homeostasis maintenance. Given its dual role in immune tolerance and host defense, IL‑2‑based therapies are a major focus of immunotherapy research. Low‑dose IL‑2 has shown promising safety and efficacy for autoimmune disease treatment. In basic research and translational applications, rhIL‑2 is widely used for in‑vitro T‑cell activation and expansion. It stabilizes CD8⁺ T‑cell viability and cytotoxicity in tumor‑T cell co‑culture assays. High‑grade rhIL‑2 features high purity, potent bioactivity, low endotoxin and strictly controlled host‑cell protein residuals, supporting reliable cell therapy and immunology studies.