Antibodies against myoid thymic cells and striated muscle, and monoclonal gammapathy in myasthenia gravis.

The serum of a patient with myasthenia gravis contained a particularly high titer of antistriated muscle antibodies, as well as a monoclonal IgM Kappa immunoglobulin. The antibody activity was only associated with IgG fractions and not with the monoclonal IgM, when these immunoglobulins were separated by chromatography. The association of these two immunological disorders is discussed.