Cathepsin D在滤泡型淋巴瘤及淋巴滤泡过度增生中的表达及意义

目的 检测溶酶体蛋白酶cathepsin D在滤泡型淋巴瘤(FL)和淋巴滤泡过度增生(FH)生发中心的表达。方法 收集10例FL和9例FH的淋巴结石蜡标本，用免疫组化LSAB法检测cathepsin D在各例标本中的表达。结果 在10例FL标本中，cathepsin D阳性信号较弱，位于瘤性滤泡生发中心树突状细胞浆内。滤泡中心部分的阳性细胞数目少，而靠近边缘部位较多。所有病例的滤泡生发中心瘤细胞cathepsin D表达阴性。在9例FH标本中，胞浆染色阳性的树突状细胞均匀弥散地分布于生发中心，阳性信号比FL组强。滤泡内少许组织细胞胞浆内也呈阳性，而滤泡内其他细胞均为阴性。滤泡生发中心周围有由T淋巴细胞组成的外套层。有4例FL的瘤性滤泡被反应性T淋巴细胞包绕，这些被包绕的滤泡中阳性细胞数目较其他6例无反应性T淋巴细胞包绕的滤泡多。在部分无T淋巴细胞包绕的滤泡中，cathepsin D阳性染色细胞甚至缺如。结论 cathepsin D可以作为滤泡树突状细胞和组织细胞良好的标志物。Cathepsin D在FL瘤性滤泡和FH滤泡树突状细胞中的差异表达可作为鉴别两种疾病的一项指标。FL瘤性滤泡中cathepsin D阳性树突状细胞的减少，可能与机体免疫系统对肿瘤细胞的免疫识别能力低下有关。

DIFFERENTIAL EXPRESSION OF CATHEPSIN D IN GERMINAL CENTER OF FOLLICULAR LYMPHOMA AND FOLLICULAR HYPERPLASIA AND ITS SIGNIFICANCE

Objective To study the expression of aspartic proteinase cathepsin D in the germinal center of follicular lymphoma and follicular hyperplasia. Methods Immunohistochemical staining was performed to detect the expression of cathepsin D in paraffin sections of 10 cases of follicular lymphoma and 9 cases of follicular hyperplasia. Results Cathepsin D was weakly expressed in the plasma of dendritic cells and histiocytes in the germinal centers of 9 out of 10 cases of follicular hyperplasia. The number of positive cells were smaller in the center of follicles, but larger in the periphery. It was more strongly expressed in the plasma of dendritic cells and histiocytes located predominantly in the peripheral areas of germinal centers of follicular lymphoma in 10 patients. Some germinal centers were surrounded by T lymphocytes in 4 cases of follicular lymphoma, and cathepsin D positive cells in these germinal centers were more in number than that in the germinal centers without being surrounded by T cells in other 6 cases of follicular lymphoma, in which positive sign even absent in some germinal centers. Conclusion Cathepsin D is a good marker for the dendritic cells and histiocytes, and its differential expression in follicular lymphoma and follicular hyperplasia is helpful for differential diagnosis of the diseases. Based on the former reports of cathepsin D with its important roles in antigen processing, we suppose that lower expression of this protease is probably due to the decreased ability of immunological response to tumor in follicular lymphoma patients.