Acetylcholine Receptor (AChR)-modulating Antibodies

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Turnaround Time: 6-7 days
CPT Code:


Test Type: 0.5mL Serum


Diagnose myasthenia gravis (MG); monitor response to treatment of myasthenia gravis.

False positives can occur in patients with serum drawn within 48 hours of administration of general anesthesia and muscle relaxants. Antibodies to a-bungarotoxin (a-BTX) may sometimes be found in patients treated with snake venom. Recently administered radioisotopes may interfere with the assay in unpredictable ways. Acetylcholine receptor autoantibodies are not typically found in congenital myasthenia gravis.

Myasthenia gravis is an autoimmune disorder manifested by muscle weakness caused by the loss or dysfunction of acetylcholine receptors (AChR) of skeletal muscle. Autoantibodies (binding, blocking, and/or modulating) to postsynaptic AChRs are detectable in the serum of 90% of patients with generalized MG and in 55% to 70% of patients with ocular myasthenia. These autoantibodies interfere with normal neuromuscular function, causing muscle weakness and fatigue. Receptor antibody levels tend to rise several weeks before symptoms increase in patients with established MG. Remission after thymectomy is associated with a progressive decline in antibody levels. Consequently, measurements of AChR antibodies can be used in monitoring disease progression as well as the effects of treatment. Modulating antibodies are responsible for the degradation of AChR at the muscle cell surface. Modulating antibodies bind to two receptor molecules on the cell surface and accelerate internalization, triggering endocytosis and degradation. The relative increase in this degradation rate closely corresponds to the disease severity.

Griesmann GE, Kryzer TJ, Lennon VA. Autoantibody profiles of myasthenia gravis and Lambert Eaton syndrome. In: Rose NR, Hamilton RG, Detrick B, eds. Manual of Clinical Laboratory Immunology. 6th ed. Washington DC: ASM Press; 2002.

Hara H, Hayashi K, Ohta K, Itoh N, Nishitani H, Ohta M. Detection and characterization of blocking-type antiacetylcholine receptor antibodies in sera from patients with myasthenia gravis. Clin Chem. 1993 Oct; 39(10):2053-2057. PubMed 8403390

Howard FM Jr, Lennon VA, Finley J, Matsumoto J, Elveback LR. Clinical correlations of antibodies that bind, block, or modulate human acetylcholine receptors in myasthenia gravis. Ann N Y Acad Sci. 1987; 505:526-538. PubMed 3479935

Howard JF Jr. Myasthenia gravis—A summary. Myasthenia Gravis Foundation of America. Carolinas Chapter Newsletter. 1997 Nov.

Lyons BW, Wu LL, Astill ME, Wu JT. Development of an assay for modulating antiacetylcholine receptor autoantibodies using human rhabdomyosarcoma cell line. J Clin Lab Anal. 1998; 12(5):315-319. PubMed 9773965

Palace J, Vincent A, Beeson D. Myasthenia gravis: Diagnostic and management dilemmas. Curr Opin Neurol. 2001 Oct; 14(5):583-589. PubMed 11562569

Wu JT, Astill M, Lloyd C, Salmon VC. Rhabdomyosarcoma cell line can be used for the isolation of soluble acetylcholine receptor for assaying blocking and modulating antibodies. J Clin Lab Anal. 1993; 7(1):11-18. PubMed 8426270

Collection Details:

Collection Instructions:

Red-top tube or gel-barrier tube.

Separate serum from cells within 45 minutes of collection. Send serum in plastic transport tube.

Refrigerate (cool pack), preferred; stable for 14 days. Stable at room temperature for seven days or frozen for two months.