[The level of Bcl-2 and Fas expression in thymoma tissue from patients with myasthenia gravis].

ABSTRACT

OBJECTIVE: To evaluate the clinical significance of expression levels of apoptosis-associated genes, bcl-2 and Fas in thymoma tissue from patients with myasthenia gravis. METHODS: The study included 25 patients who underwent maximal thymectomy because of concurrent thymoma and myasthenia gravis. Clinical staging (Osserman classification) showed stage I in 6, IIA in 3, IIB in 13 and III in 3 cases. According to the WHO classification of thymomas (1999), 5, 3, 7, 7, and 3 patients had type A, AB, B1, B2, and B3, respectively, and no patient had type C. As a control group, the normal thymic tissue from 25 patients with congenital heart diseases was studied. The expression level of Bcl-2 and Fas in the tissue of thymoma and normal thymus was detected by immunohistochemistry. RESULTS: Bcl-2 and Fas expressions were significantly higher in thymomas compared with normal thymus by Radit analyses (U = 2.645, P < 0.05 and U = 3.200, P < 0.05, respectively). The expression level of Bcl-2 and Fas showed no relation to the course of the disease, age, Osserman classification and sex. CONCLUSION: The result suggests that the two apoptosis-associated factors, Bcl-2 and Fas, may play important roles in the pathogenesis of thymoma concurrent with myasthenia gravis.