A 28-year-old woman presents with weight loss, heat intolerance, exophthalmos, and diffuse goiter. Her thyroid stimulation is caused by autoantibodies that bind the TSH receptor and mimic TSH activity. In the Gell and Coombs framework this disease exemplifies which hypersensitivity type?

• A Type I, mediated by IgE on mast cells
• B Type IV, mediated by CD4+ T cells and macrophages
• C Type III, mediated by circulating immune complexes
• D Type II, mediated by antibody directed against cell surface receptors ✓

Explanation

Graves disease is the classic example of type II hypersensitivity causing disease by stimulation rather than destruction: TSIs (thyroid-stimulating immunoglobulins) bind the TSH receptor and constitutively activate it, driving hormone synthesis independent of pituitary feedback. Type I requires IgE and mast cell degranulation, type III requires soluble antigen-antibody complex deposition, and type IV is T-cell mediated; none operate here.

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.