Acetylcholine Receptor AChR Binding Antibodies
Also Known as: AChR Antibody, Muscle nicotinic Acetylcholine Receptor (AChR) Binding Antibody, Myasthenia Gravis Antibodies, Acetylcholine Receptor Binding Antibody, Acetylcholine Receptor Blocking Antibody, Acetylcholine Receptor Modulating Antibody.
What is an Acetylcholine Receptor (AChR) Antibody test?
AChR antibodies in the blood are detected and measured by this test. Autoantibodies to acetylcholine receptors (AChR) are made by the immune system that mistakenly targets proteins called acetylcholine receptors on muscles that you voluntarily control (known as skeletal muscle fibers). When an impulse travels along a nerve, it triggers the production of acetylcholine, a chemical substance (neurotransmitter) that conveys signals between specific types of cells. Acetylcholine crosses the "neuromuscular junction," which is a very small space between a nerve ending and a muscle fiber. When acetylcholine reaches the muscle fiber, it binds to one of the numerous acetylcholine receptors and activates it, causing the muscle fiber to contract.
By preventing acetylcholine receptor activation, AChR antibodies obstruct nerve-skeletal muscle communication, decrease muscular contraction, and cause rapid muscle fatigue. They accomplish this in three ways:
- Binding antibodies bind to receptors on nerve cells and may cause an inflammatory response that damages the receptors.
- Antibodies that attach to cholinergic receptors may block acetylcholine from binding.
- Antibodies that cross-link receptors may cause them to be taken up into muscle cells and removed from the neuromuscular junction.
The development of myasthenia gravis (MG), a chronic autoimmune condition linked to the presence of these antibodies and their effects on muscular function, is the result of this interference. Antibodies to AChR can be identified in a variety of ways to determine which mechanism is causing the problem, and they can be labeled as "binding," "blocking," or "modulating." The technique that assesses "binding" is, however, the most often used, and it is uncommon for the other two tests to be positive without the "binding" test being positive as well.