Human interleukin‑6 (IL‑6) is a pleiotropic cytokine that centrally mediates immune regulation, inflammatory reactions and hematopoiesis under both physiological and pathological conditions. It is mainly produced by activated T cells, B cells, monocytes/macrophages, fibroblasts and endothelial cells. IL‑6 signals through a receptor complex consisting of IL‑6Rα (gp80) and the signal‑transducing subunit gp130, triggering downstream pathways including JAK/STAT3. It promotes B‑cell proliferation and plasma cell differentiation for antibody production, and modulates T‑cell activation and differentiation. As a major inducer of acute‑phase responses, IL‑6 stimulates hepatocytes to synthesize acute‑phase proteins such as C‑reactive protein (CRP). It also synergizes with IL‑3 to drive megakaryocyte maturation and platelet generation, and participates in bone metabolism regulation. Recombinant human IL‑6 is a widely used research reagent, commonly expressed in E. coli, CHO or HEK293 systems. Supplied as high‑purity, low‑endotoxin lyophilized powder with verified bioactivity, it supports multiple in‑vitro functional assays, including induction of acute‑phase protein synthesis and B‑cell differentiation studies.