A peripheral smear from a child with visceral larva migrans shows granulocytes with bilobed nuclei and coarse refractile granules; their major basic protein is toxic to helminths. These cells accumulate preferentially in reactions involving which immunoglobulin?

• A IgG directed against bacterial capsule polysaccharides
• B IgE bound to parasite antigens and mast cells ✓
• C IgM fixing complement on viral envelopes
• D IgA secreted across mucosal surfaces

Explanation

Eosinophils are characteristic of IgE mediated allergic reactions and helminthic infections. Parasite specific IgE crosslinks Fc epsilon RI on mast cells, releasing eotaxin and other signals that recruit eosinophils, whose major basic protein damages the parasite tegument. IgG and IgM mediate complement dependent bacterial and viral defense handled chiefly by neutrophils, and IgA provides mucosal neutralization without eosinophil recruitment.

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.