Question

In myasthenia gravis, an autoimmune disease, auto-antibodies bind to

• A. Adrenal cortex cells
• B. Collagen
• C. Insulin receptor
• D. Acetylcholine receptor at the neuromuscular junction

Hint:

Autoimmune Targets:
Myasthenia Gravis $\rightarrow$ Post-synaptic Nicotinic ACh Receptors.
Graves' Disease $\rightarrow$ TSH Receptor.
Hashimoto's $\rightarrow$ Thyroid Peroxidase.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Autoimmune neuromuscular junction disorders feature pathogenic autoantibody-mediated blockade and degradation of post-synaptic receptors.

Step 2: Detailed Explanation:
Myasthenia Gravis:
- A classic organ-specific Type II hypersensitivity autoimmune disorder.
- Pathogenic IgG autoantibodies are directed against nicotinic Acetylcholine Receptors (nAChRs) on the postsynaptic motor endplate membrane at the neuromuscular junction.
- Antibody binding blocks ACh neurotransmitter binding, accelerates receptor endocytosis/degradation, and triggers complement-mediated destruction of endplate junctional folds, causing progressive skeletal muscle weakness and fatigue.

Step 3: Final Answer:
Thus, auto-antibodies bind to Acetylcholine receptor at the neuromuscular junction, corresponding to option (D).