Acetylcholine Receptor Antibodies

Acetylcholine Receptor Antibodies
(AChR, Anti-ACh Antibodies)
Test Description
Acetylcholine (ACh) and the catecholamines (epinephrine and norepinephrine) are the main neurotransmitters of the autonomic nervous system. In normal contraction of the muscles, ACh is released from the terminal end of the nerve into the neuromuscular junction. ACh then binds with receptor sites on the muscle membrane, resulting in the opening of sodium channels. This allows sodium ions to enter and depolarize the cell. This begins an action potential that passes along the entire muscle fiber, resulting in muscle contraction.
Myasthenia gravis (MG) is an autoimmune disease that affects neuromuscular transmission. In this disease, antibodies form that interfere with the binding of ACh to the receptor sites on the muscle membrane. This prevents muscle contraction from occurring. These antibodies are present in more than 85% of the patients with MG. Thus, this test is used for diagnosis of MG and for monitoring the patient’s response to immunosuppressive therapy for the disease.