Mouse Anti-Human IL-9R (CD129) Antibody (S-3903)

Interleukin-9 receptor (IL-9R), also designated as CD129, is a type I transmembrane protein that functions as the specific alpha subunit of the receptor complex for interleukin-9 (IL-9), a multifunctional cytokine primarily associated with Th9 cell responses and allergic inflammation. Structurally, IL-9R consists of an extracellular domain responsible for ligand binding, a single transmembrane helix, and an intracellular domain that lacks intrinsic kinase activity but recruits the common gamma chain (γc, CD132) to form a high-affinity signaling complex; upon IL-9 binding, this heterodimeric assembly activates the Janus kinase (JAK)/Signal Transducer and Activator of Transcription (STAT) pathway, predominantly triggering the phosphorylation of JAK1, JAK3, STAT1, STAT3, and STAT5, which subsequently modulates gene expression involved in cell proliferation, survival, and differentiation. Biologically, IL-9R expression is observed on various hematopoietic cells, including T cells, mast cells, eosinophils, and epithelial cells, playing a critical role in host defense against parasitic infections while simultaneously contributing to the pathogenesis of asthma, atopic dermatitis, and certain malignancies, thereby making it a significant target for therapeutic interventions aimed at inhibiting aberrant immune responses.