B-cell lymphopenia and hypogammaglobulinemia in thymoma patients.

Thymic tumors represent a unique neoplastic disease associated with various immune-mediated syndromes. Immune impairment is generically recognized to be associated with thymoma. Hypogammaglobulinemia and recurrent pulmonary infections in thymoma patients define Good's syndrome. Apart from sporadic reports focusing on this topic, there is still a lack of knowledge on immune assessment and clinical sequelae in thymoma patients. The present study was performed to evaluate immunoglobulin levels, CD19(+) B lymphocytes, and CD3(+) T lymphocytes in a large series of thymoma patients from a single institution. The occurrence of recurrent severe infections was related to immunological findings to identify the possible correlation with the immunodeficiency status. Eighteen patients (eight males, ten females, mean age: 56 years, range: 19-75) with a pathological diagnosis of thymic tumor were studied. Six patients suffered from clinical recurrent pulmonary infections. Blood samples were collected to measure serum immunoglobulins and analyze immunophenotype. Low T lymphocyte number was found in 22% of the patients. T lymphocytosis was present in one patient. Panhypogammaglobulinemia was found in 4 of 18 patients (22%). Conversely B lymphopenia was a frequent finding in this series of thymoma patients (9 of 18, 50%). Five of six patients (83%) with recurrent infections had B lymphopenia, while only two (33%) had panhypogammaglobulinemia. B lymphopenia often occurred in this series of thymoma patients and was related to susceptibility to recurrent infections more than hypogammaglobulinemia. Therefore, immunophenotype has to be monitored in follow-up of thymoma patients because it may reveal significant abnormalities.

Immunological findings in thymoma and thymoma-related syndromes.

Human thymoma is a neoplasm of thymic epithelial cells associated with several clinical syndromes ranging from autoimmune disease to immunodeficiency. The aim of our research was to investigate T cell-mediated immune response in patients with thymoma. Initially eight patients were enrolled in this study. Four patients underwent surgical removal of the thymus, while four were submitted to diagnostic procedures only. Inversion of the CD4:CD8 ratio was found in three patients. Only one subject displayed a normal CD19 count in peripheral blood. The mean value (+/-SD) of the CD19 percentage in the patient group was 2 +/- 2.2. Notably, the patients with thymoma had fewer mature B lymphocytes than the thymectomized patients. The T-cell receptor (TCR) repertoire was investigated in three individuals affected by thymoma: one underwent thymectomy, while the two others, one of which presented with lymphocytosis, were submitted to diagnostic biopsies only. The preliminary results showed a marked alteration in the CD8 repertoire of the thymectomized patient but not in that of the lymphocytotic patient. However, alterations in the TCR repertoire were also found in one patient with thymoma. Altogether, these preliminary findings reveal that loss of CD19+ lymphocytes in peripheral blood is a frequent phenomena in thymoma patients. In this article we discuss this aspect in the context of alterations of the TCR repertoire.