Interleukin-15 receptor quaternary complex (IL-15–IL-15Rα–IL-2Rβ–γc) (IL-15R quaternary complex)

The Interleukin-15 receptor quaternary complex is the molecular unit mediating IL-15 signaling. IL-15 first binds with high affinity to IL-15Rα (the alpha subunit), often in the *trans*-presentation mode by antigen-presenting or stromal cells. This complex then associates with the beta (IL-2Rβ) and common gamma (γc) receptor subunits present on responding lymphocytes (NK cells, CD8+ T cells), triggering intracellular signaling pathways (e.g., JAK/STAT, PI3K/AKT). This receptor assembly is essential for immune cell survival, proliferation, and function, and is a focus for therapeutic manipulation in cancer immunotherapy and infectious disease. The terminology in literature varies; the standard is to specify all subunits as IL-15–IL-15Rα–IL-2Rβ–γc.

Other names

IL-15 receptor complexIL-15R quaternary complexIL-15–IL-15Rα complex (when not including β/γ subunits)IL-2Rβ/γ (by shared subunits)

Agonists: promote or mimic IL-15 binding and activation, resulting in immune cell proliferation, survival (often by *trans*-presentation). Antagonists: block any subunit or disrupt complex formation, reducing immune activation. Superagonist complexes: combine IL-15 with IL-15Rα to stabilize and amplify signaling.