[Thymomas (author's transl)].

Immunological investigations concerning pathological autoantibodies and defects of humoral immunity were performed in 7 patients with thymomas, 5 of which showed invasive growth. The number of B and T lymphocytes in blood was determined at the same time using membrane markers as well as blood lymphocyte stimulation with phytohaemagglutinine. Two of the 3 patients with auto-antibodies against striated muscles or nuclei showed the clinical signs of accompanying disease (myasthenia gravis, lupus erythematodes). A humoral immunodisturbance with IgM deficiency was demonstrable in one patient and was accompanied by clinical symptoms. Lymphopenia with decreased numbers and functional disturbance of T and B lymphocytes could be shown in the majority of patients. Immunological investigations simplify proof of accompanying diseases in thymomas. These represent an important prognostic criterium in the same way as does invasive growth.