CD125 antibody targets the alpha subunit of the interleukin-5 receptor (IL-5Rα), a key component in the IL-5 signaling pathway. IL-5 is a cytokine primarily involved in the growth, differentiation, and activation of eosinophils, a type of white blood cell critical in immune responses against parasites and in allergic inflammation. The IL-5 receptor consists of two subunits: IL-5Rα (CD125), which binds IL-5 with low affinity, and a common beta subunit (βc) shared with IL-3 and GM-CSF receptors, enabling high-affinity signaling. Dysregulation of this pathway is implicated in eosinophil-associated disorders, such as asthma, chronic rhinosinusitis with nasal polyps, hypereosinophilic syndromes, and certain leukemias.
CD125 antibodies, typically monoclonal antibodies (mAbs), are designed to block IL-5/IL-5Rα interactions, thereby inhibiting eosinophil proliferation, survival, and tissue recruitment. Benralizumab, an FDA-approved anti-CD125 mAb, depletes eosinophils via antibody-dependent cellular cytotoxicity (ADCC), showing efficacy in severe eosinophilic asthma. Research also explores CD125-targeted therapies for eosinophilic esophagitis, atopic dermatitis, and hematologic malignancies. Beyond therapeutics, CD125 antibodies serve as tools in research to study IL-5R expression and eosinophil biology. Challenges include optimizing specificity and addressing potential immunosuppressive effects. Overall, CD125 antibodies represent a strategic approach to modulate eosinophil-driven inflammation, offering targeted treatment for diseases with limited therapeutic options.