HL-A antigens, autoantibody production, and associated diseases in thymoma patients, with and without myasthenia gravis.

The sera of 67 patients with thymomas-43 with myasthenia gravis (thymoma(+) MG(+)) and 24 without myasthenia gravis (thymoma (+) MG (-)) from 5 Dutch centers were examined with the indirect immunofluorescence test for the presence of antibodies reacting with skeletal muscle (AMA), thyroid tissue, gastric parietal cells, adrenocortex and antinuclear antibodies (ANA). The data were compared with those obtained in a group 83 MG patients in whom a thymoma was excluded by histological verification (thymoma (-) MG (+)) and with 1106 controls from the normal population. Histocompatibility (HL-A) antigens were tested in 24 thymoma (+) MG (+), 23 thymoma (+) MG (-), and 43 thymoma (-) MG (+) patients and 533 controls from the Dutch population. AMA was found in all thymoma (+) MG (+) cases, in 42% of thymoma (+) MG (-), in 11% of thymoma (-) MG (+), and in less than 1% of the controls. The differences between each of these groups are significant (p less than 0.01, Table 3.) ANA was found in 54%, 50%, 18%, and 4%, respectively, of the above mentioned groups. The differences between the thymoma (+) and the thymoma (-) groups are significant (p less than 0.001. Table 4). The frequencies of antibodies reacting with thyroid tissue, gastric parietal cells and adrenocortex were low and showed no differences between the groups. The frequencies of HL-A8 were significantly decreased in both thymoma groups that had a relatively high incidence of associated immunological disorders (Table 5). Patients with MG and without antimuscle antibodies have no thymomas: This rule is of practical value in the management of the MG patient.