The Role of the Thymus in Myasthenia Gravis
The Role of the Thymus in Myasthenia Gravis
Although the association between thymic hyperplasia / thymoma and autoimmune myasthenia
 gravis has been known for some time, the question of causality remains uncertain. Recent
 research findings indicate, however, that especially in myasthenia patients with thymomas a
 non-physiological export of naive CD4 + T-cells can take place by the tumour and this could
 possibly play an important role in the pathogenesis of myasthenia gravis. The investigators
 want to analyse the functionality and specificity of t-cells generated in thymomas as well as
 the effect of thymectomy on the immune system.
On one hand we want to perform a detailed analysis of the T-cells generated in thymomas in
 terms of their functional capacity and their specificity. We will analyse blood and thymoma
 tissue of patients with myasthenia gravis with thymona, patients with myasthenia gravis
 without thymona, and patients with thymona without myasthenia gravis.

 Hypothesis: The T-cells which are generated in the thymoma in thymoma-associated myasthenia
 gravis can be differentiated from T-cells which are generated in normal thymoma tissue with
 regard to functionality and T-cell receptor specificity. This non-physiological T-cell
 maturation might be the cause for the formation of auto-antibodies.

 On the other hand we want to examine the effects of thymectomy on the immune system in the
 context of myasthenia gravis. We will analyse blood and thymoma tissue of patients with
 myasthenia gravis with thymona, patients with myasthenia gravis without thymona, patients
 with thymona without myasthenia gravis and patients with cardiac, or thyroid surgery.

 Hypothesis:

 1. Thymectomy in patients with myasthenia gravis leads to a reduced number of
 auto-reactive, e.g. Acetylcholine receptor (ACh-R)-specific T cells. In contrast,
 T-cells with other specifities, for example against CMV or tetanus, are not affected.

 2. The non-physiological export of thymocytes from thymomas leads to a significant shift in
 leukocyte populations in peripheral blood.
Inclusion Criteria:

 -  Patients with compelling indications for thymectomy due to thymoma (with or without
 myasthenia gravis), Or

 -  Patients with elective indication for thymectomy due to thymoma without myasthenia
 gravis

 -  Patients with indication for a heart or thyroid surgery, in which for op-technical
 reasons, a (partial) resection of the thymus is performed.

 -  Signed informed consent form

 -  Age > 17 Years

 Exclusion Criteria:

 -  Other immunological diseases such as rheumatoid arthritis, multiple sclerosis