Both binding and blocking antibodies correlate with disease severity in myasthenia gravis

Abstract

Myasthenia gravis (MG) is an autoimmune disease associated with antibodies directed to the postsynaptic muscle components of the neuromuscular junction. The heterogeneous nature of the acetylcholine receptor (AChR) antibody response had led to the categorization of AChR antibodies into 3 types: binding, blocking, and modulating antibodies. The purpose of this study is to compare the AChR antibodies' type with the clinical severity of MG patients. The patients enrolled in the study had been tested for both binding and blocking antibodies and had disease duration exceeding 2 years since diagnosis. The patients were divided into five main classes by the Myasthenia Gravis Foundation of America clinical classification. Again, the enrolled patients were divided into ocular and generalized group. We compared the type and titer of antibodies and the thymus status between the ocular and generalized group. Thirty-five patients met the inclusion criteria. Of these, 16 patients (47 %) had both blocking and binding AChR antibodies, 11 patients (31 %) had only binding antibodies, and 8 patients (22 %) had only blocking antibodies. By defined clinical classification, the ocular and generalized groups included 10 and 25 patients, respectively. Sixteen patients in the generalized group possessed both AChR antibodies, with the remaining patients displaying only the binding antibody. All the patients with only blocking antibody were classified into ocular group. Use of binding and blocking antibodies' tests may, therefore, be more helpful in predicting the prognosis and diagnoses of MG patient.