IL-4R alpha/CD124

Interleukin-4 receptor alpha (CD124) is the ligand-binding alpha chain shared by the receptors for IL-4 and IL-13, cytokines that orchestrate type 2 immunity, IgE class switching, and alternative macrophage activation. Signaling proceeds through two alternative partner chains: pairing with the common gamma chain forms the type I IL-4 receptor, whereas association with IL-13R alpha 1 forms the type II receptor that responds to both cytokines. Downstream JAK-STAT6 signaling drives allergic inflammation, and CD124 is strongly expressed on endothelial cells in atopic tissues. Dupilumab binds IL-4R alpha itself, making CD124 a clinically validated intervention point in atopic dermatitis and asthma.