I think myasthenia gravis is an autoimmune problem due to type II hypersensitivity, but Th cells can be involved in activating b-cells. Thymoma is often associated with myasthenia gravis. It is often treated with acholinesterase inhibitor or immune modulating drugs. Plasmapheresis & thymectomy are other options. It is certainly a devastating disease, but still a disease that can be managed to a large extent.