A biopsy of a subcutaneous nodule in a child with toxocariasis shows a dense infiltrate of bilobed granulocytes with bright red-orange granules. The granule constituent chiefly responsible for killing helminthic larvae is:

• A Major basic protein ✓
• B Myeloperoxidase
• C Lysozyme
• D Defensins

Explanation

Eosinophils are recruited to IgE-coated parasites and release their granule contents; major basic protein, a highly cationic protein constituting about half of the eosinophil granule mass, is directly toxic to helminthic larvae. Myeloperoxidase and lysozyme are neutrophil azurophilic granule enzymes acting on bacteria, and defensins are antimicrobial peptides of neutrophils, none of which target multicellular parasites effectively.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.