Graves disease is classified under which type of hypersensitivity reaction, and what is the functional effect of the pathogenic autoantibody?

• A Type II, blocks acetylcholine receptors
• B Type II, stimulates the TSH receptor ✓
• C Type III, forms immune complexes deposited in thyroid
• D Type IV, CD4-mediated cytotoxicity against thyrocytes

Explanation

Graves disease is a type II (antibody-mediated) hypersensitivity where autoantibodies bind and stimulate the TSH receptor, driving unregulated thyroid hormone synthesis. This is the classic example of a stimulating antibody rather than an opsonizing or blocking one. The blocking option describes myasthenia gravis, and immune complex deposition is characteristic of type III reactions such as serum sickness.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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