P17: Do associated auto-antibodies influence the outcome of myasthenia gravis after thymectomy?

Abstract: Myasthenia gravis (MG) is a neuromuscular autoimmune disease, where antibodies against the acetylcholine receptor destroy this receptor. The role of thymectomy in the treatment of MG remains controversial. Because of the frequent association with other autoimmune diseases, we hypothesized that patients with multiple autoantibodies (autoAbs) might have a lower chance of reaching complete stable remission after thymectomy. We analyzed sera of 85 MG patients who underwent a thymectomy between April 2004 and December 2012. We used four different immunodot kits (D-Tek, Mons, Belgium): ANA25 Quantrix, Synthetase 10 Diver, Myositis 7 Diver and Liver 10 profile Diver, all automatized on the BlueDiver Instrument (D-Tek). The Myasthenia Gravis Foundation of America (MGFA) postintervention status was used to determine the outcome after thymectomy. AutoAbs other than anti-acetylcholine receptor (AChR) antibodies were detected in 29.4% of the patients of whom 16.5% clinically had a second autoimmune disease. In none of the seronegative patients other autoAbs were detected. No significant difference was observed in the 3-years remission rate after thymectomy in patients with or without antibodies other than anti-AChR antibodies. Although these autoAbs do not predict outcome in our MG patient cohort, screening for multiple autoAbs in MG patients might be warranted to identify patients with additional autoimmune diseases.

Keywords: Thymectomy; myasthenia gravis; BlueDiver instrument; auto-antibodies