Detection of multiple antibodies in myasthenia gravis and its clinical significance

Antibodies against acetylcholine receptor, acetylcholinesterase, ryanodine receptor and titin have been found in patients with myasthenia gravis. However, the relations between these antibodies and character of myasthenia gravis are unknown. This study aimed to detect multiple antibodies in myasthenia gravis and to investigate its clinical significance.

These antibodies were detected by enzyme-linked immunoabsorbent assay in 89 cases of myasthenia gravis, 66 cases of other neurological diseases and 66 healthy controls. The incidences of antibodies were compared using the chi-square test.

Acetylcholine receptor, acetylcholinesterase, titin and ryanodine receptor antibodies were detected in 53.9%, 20.2%, 64.0% and 55.0% of myasthenia gravis patients respectively, higher than in patients of other neurological diseases and controls groups. The combination of the four antibodies assays provided 94.4% sensitivity and 84.0% specificity for the diagnosis of myasthenia gravis. Acetylcholinesterase antibody occurred more frequently in acetylcholine receptor antibody negative patients with adverse reactions to neostigmine test. Titin antibody provided 82.1% sensitivity and 52.5% specificity for myasthenia gravis with thymoma. Incidences of titin and of ryanodine receptor antibody were higher in late onset myasthenia gravis than in early onset myasthenia gravis. The proportion of titin antibody positive patients increased with the severity of myasthenia gravis as graded by a modified Osserman scale.

Testing for acetylcholine receptor, acetylcholinesterase, titin and ryanodine receptor antibodies can offer a better diagnostic method for myasthenia gravis than each antibody test alone. Titin antibody combined with computed tomography was better for the diagnosis of thymoma. Titin antibody occurred most frequently in severe myasthenia gravis.