Delayed hypersensitivity to muscle and thymus in myasthenia gravis and polymyositis.

Delayed hypersensitivity reactions appear to be important in the two main muscular human diseases involving autoimmune anomalies. Using the leucocyte migration test (LMT), a significant abnormality was detected in twelve out of fourteen polymyositis (PM) patients, and in forty out of forty-six myasthenics, in the presence of muscle antigens. No abnormal reactions in the presence of monkey thymus in the LMT were observed amongst the PM patients, as opposed to twenty-one abnormal reactions out of forty-two myasthenics. Secretion of migration inhibition factor (MIF) in the presence of muscular antigens is in accordance with what is known about hypersensitivity reactions during the course of polymyositis. In myasthenia gravis (MG), delayed hypersensitivity to muscle antigens was found to be frequent, and this also applies to thymic antigens, which are considered important in this disease. The role of the T lymphocytes in the neuromuscular junction still remains hypothetical.