A 55-year-old asthmatic on step 4 therapy develops eosinophilic asthma (blood eosinophils >300 cells/µL). A biologic is added. Mepolizumab works by:

• A Blocking IL-5, preventing eosinophil maturation, survival, and activation ✓
• B Blocking IgE at its high-affinity FcεRI binding site, preventing mast cell activation
• C Blocking TSLP, preventing dendritic cell activation and downstream Th2 priming
• D Blocking IL-4 and IL-13 receptors simultaneously, reducing eosinophil recruitment

Explanation

Mepolizumab is a humanized anti-IL-5 monoclonal antibody. IL-5 is the primary cytokine governing eosinophil development in bone marrow, their release into blood, and their survival in tissues. Blocking IL-5 markedly reduces blood and sputum eosinophil counts, decreasing asthma exacerbation rates in patients with severe eosinophilic asthma. Omalizumab blocks free IgE (option B). Tezepelumab blocks TSLP (option C). Dupilumab blocks the shared IL-4Rα subunit, inhibiting both IL-4 and IL-13 signaling (option D). Benralizumab targets IL-5 receptor alpha directly, depleting eosinophils via ADCC.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.