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

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.