Higher amounts of anti-acetylcholine receptor (AchR) antibodies in the blood before surgically removing the thymus could be a good predictor of outcomes for patients with myasthenia gravis, a study published in the Open Journal of Thoracic Surgery suggests.
Myasthenia gravis is an autoimmune disease characterized by the uncontrolled production of anti-AchR antibodies. About 85% of patient with generalized myasthenia gravis are positive for anti-AchR antibodies, while only about 50% of patients with ocular myasthenia gravis are positive.
Anti-AchR antibodies block the communication between nerve and muscle cells, preventing electrical pulses from flowing normally and muscles from contracting.
During normal development, the thymus, a gland where immune cells reside and develop, shrinks. But in many myasthenia gravis cases, the thymus remains enlarged. Some patients also develop thymomas, which are benign growths of thymus tissue. It is still unclear what the role of the thymus is in the development of myasthenia gravis. But its removal via surgery, called a thymectomy, has shown to reduce symptoms and lead to clinical remission in many cases.
In the study titled, “The Effect of Preoperative AchR-Ab Level to the Prognosis in Operated Myasthenia Gravis Patients,” researchers at Ege University, in Izmir, Turkey, analyzed the impact of anti-AchR antibodies on the outcome of patients with myasthenia gravis who underwent a thymectomy.
The study included 37 patients with diagnosed myasthenia gravis who were referred to surgery due to the presence of thymoma (25 patients) or an increased thymus (12 patients). After surgery, the patients were followed for an average of 23 months.
During the follow-up period, 25 patients reported having fewer symptoms, while 10 patients reported no changes. Twenty-one patients reduced their dosage of acetylcholinesterase (AChE) inhibitors and corticosteroids, while 12 patients reported no changes in dosage for any of the treatment regimens. Only two patients needed to increase the dose of the drugs used to manage their symptoms.
The average concentration of anti-AchR antibodies before surgery was 144.7 nmol/L (ranging from 0.1 to 1,806 nmol/L), which is much higher than the standard threshold (0.4 nmol/L).
Analysis of the average levels of anti-AchR antibodies before surgery showed that patients with higher amounts reported fewer symptoms and reduced therapy dosage by the end of the 23-month follow-up period. In addition, those with poorer outcomes, no changes in symptoms, or increased treatment doses, showed lower average levels of anti-AchR antibodies.
“We concluded that the preoperative level of AchR-Ab [anti-AchR antibody] was associated with postoperative dosage of anticholinesterase [AChE inhibitors] and corticosteroids and severity of symptoms postoperatively,” the researchers stated.
The researchers believe that the amount of anti-AchR antibodies-Ab levels can be a marker to predict the effectiveness of thymic surgery.