Interleukin-5 receptor complex (IL-5R) (IL-5R)

The Interleukin-5 receptor complex (IL-5R) is a heterodimeric transmembrane protein assembly primarily expressed on eosinophils, basophils, and some mast cells (UniProt: P12333). It consists of a ligand-specific alpha subunit (IL-5Rα or CD125) and a signal-transducing common beta subunit (βc or CD131) that is shared with the receptors for IL-3 and GM-CSF (PubMed: 25637461). The primary biological function of this complex is to mediate signaling for Interleukin-5, the key cytokine responsible for the differentiation, maturation, recruitment, and survival of eosinophils (StatPearls: NBK541031). Dysregulation or overproduction of IL-5 and its subsequent binding to the IL-5R complex is a central driver in eosinophilic inflammatory diseases, most notably severe eosinophilic asthma and hypereosinophilic syndromes (PubMed: 30143312). Therapeutic intervention typically involves monoclonal antibodies that either sequester the IL-5 ligand (e.g., mepolizumab, reslizumab) or bind directly to the IL-5Rα subunit (e.g., benralizumab) to block signaling and induce eosinophil apoptosis (NIH: PMC5846117). These therapies have proven highly effective in reducing exacerbation rates and improving lung function in patients with high eosinophil biomarkers.

Other names

IL5RCD125Interleukin-5 receptor subunit alphaIL-5RACommon beta chainCD131CSF2RBCytokine receptor common subunit betaIL5 receptor

Monoclonal antibodies target the IL-5/IL-5R axis by either neutralizing the IL-5 ligand to prevent receptor binding or by binding to the IL-5R alpha subunit to block signaling and trigger eosinophil depletion via antibody-dependent cell-mediated cytotoxicity (ADCC) (StatPearls: NBK541031; NIH: PMC5846117).