| Budget Amount *help |
¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 1998: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1997: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Research Abstract |
1. Over 2000 cases of thymic tissue which were surgically resected or obtained at autopsy were histological1y examined. "Microscopic thymoma" was detected in only one thymus. However, it has not been determined whether it represents true neoplasm or not by immunohistochemical methods. To investigate the extent of apoptosis and the expression of bcl-2 in the progression of thymic epithelial tumors, 35 tumors were examined by immunohistochemical techniques. The high-grade thymic carcinoma (HGTC) showed the highest apoptotic indices of the tumor cells with significant difference between those of thymomas or well-differentiated thymic carcinoma (WDTC). bcl-2 protein was expressed in the tumor cells of the medullary-type thymomas and of the HGTC but not in the other types of thymoma or WDTC.
2. CD5 expression was examined in 73 cases of malignant tumors of various organs, 22 cases of thymoma, and 7 cases of thymic carcinoma by immunohistochemistry using NCL-CD5-4C7. All cases of thymic carci
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noma showed positive staining for CD5. Two of 4 cases of atypical thymoma also showed focal positivity, whereas the other types of thymoma were negative, which may support the hypothesis suggesting progression of atypical thymoma to thymic carcinoma. CD5 was also detected in cases of malignant tumors other than squamous cell carcinoma.
3. Techniques in examination of thymic epithelial tumors were refined. Effects of prefixation and fixation times on apoptosis detection by TUNEL method were examined. The fixation times showed no effect, but prefixation times longer than two hours resulted in false positive cells.
4.40 thymic epithelial tumors were examined by immunohistochemistry using PE-35 monoclonal antibody which reacts exclusively with the medullary epithelium in the thymus. Medullary, mixed, and predominantly cortical thymomas were PE-35 positive, whereas cortical thymomas were largely PE-35 negative. 4 of 6 WDTC were focally positive with PE-35 and all HGTC were PE-35 positive. These results suggested that medullaiy thymoma generally possesses the medullary nature and mixed and predominantly cortical thymomas may have mixed medullary phenotype and cortical function. Cortical thymoma and many of WDTC may possess the cortical nature with the tendency of losing cortical function. Less
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