Acetylcholine receptor (AChR) antibodies are autoantibodies produced by the immune system that mistakenly target proteins called acetylcholine receptors that are located on skeletal muscle fibres. This test detects and measures AChR antibodies in the blood. Acetylcholine receptors function as “docking stations” for acetylcholine, a chemical substance (neurotransmitter) that transmits messages between nerve cells. Muscle movement…Acetylcholine receptor (AChR) antibodies are autoantibodies produced by the immune system that mistakenly target proteins called acetylcholine receptors that are located on skeletal muscle fibres. This test detects and measures AChR antibodies in the blood. Acetylcholine receptors function as “docking stations” for acetylcholine, a chemical substance (neurotransmitter) that transmits messages between nerve cells. Muscle movement starts when an impulse is sent down a nerve to the nerve ending, where it stimulates the release of acetylcholine. Acetylcholine travels across a microscopic gap between the nerve ending and a muscle fibre at the “neuromuscular junction.” When it reaches the muscle fibre, it binds to one of many acetylcholine receptors and activates it, initiating muscle contraction. AchR antibodies impede communication between nerves and skeletal muscles, inhibit muscle contraction, and cause rapid muscle fatigue by preventing activation of the acetylcholine receptors. They do this in three major ways:When they bind to the receptors, the antibodies may initiate an inflammatory reaction that destroys them and the neuromuscular junction. The antibodies may sit on the receptors, preventing acetylcholine from binding. The antibodies may cross-link the receptors, causing them to be taken up into the muscle cell and removed from the neuromuscular junction. The end result of this interference is the development of myasthenia gravis (MG), a chronic autoimmune disorder associated with the presence of these antibodies and with their effects on muscle control. AchR antibodies may be detected in different ways however, the technique that measures binding antibodies is the most commonly performed and, generally speaking, it is rare for other tests to be undertaken. Other approaches may be useful when the doctor strongly suspects myasthenia gravis and the first line AchR antibody test is negative. How is the sample collected for testing? A blood sample is obtained by inserting a needle into a vein in the arm. Is any test preparation needed to ensure the quality of the sample? No test preparation is needed. See MoreSee Less
