EB病毒诱发人B细胞淋巴瘤的分子病理特性

EB病毒 (EBV ,Epstein Barrvirus)与人类多种肿瘤有关 ,尤其是与鼻咽癌和淋巴瘤的关系密切。为此研究了EB病毒在huPBL SCID嵌合体小鼠体内诱发人B细胞淋巴瘤的分子特性及肿瘤发生机制。从健康成人外周血分离出淋巴细胞 ,将之移植到SCID小鼠腹腔内 ,实验感染EBV ,观察肿瘤的形成 ;采用单向免疫扩散法连续监测小鼠血清中人IgG的含量。分别用PCR方法检测肿瘤组织中是否存在人Alu序列 ,原位杂交检测肿瘤组织中EB病毒小RNA分子EBER 1;免疫组织化学方法检测人白细胞分化抗原 (CD4 5、CD2 0、CD4 5RO、CD3) ,病毒基因(LMP1、EBNA2、BZLF1)的表达 ,以及细胞瘤基因蛋白 (p5 3、C myc、Bcl 2、Bax)在诱发肿瘤中的表达情况。结果发现 ,实验中 34只感染EBV的huPBL SCID小鼠有 2 4只诱发出肿瘤 ,根据病理形态学特征、Alu PCR和免疫标志均证实诱发瘤是人源性B淋巴细胞肿瘤。原位分子杂交显示肿瘤细胞核内存在EBER 1,少数瘤细胞表达EB病毒BZLF1蛋白阳性 ,部分瘤细胞表达LMP1和EBNA2蛋白阳性。连续监测 12只huPBL SCID小鼠血清中人IgG含量 ,发现IgG水平随诱瘤时间延长和肿瘤生长有逐渐增高趋势。免疫组化显示诱发的 2 4例淋巴瘤组织p5 3、C myc、Bcl 2和Bax蛋白表达阳性率分别为 83.33%、10 0 %、95 .83%、91.6 7%。结果

Molecular Pathological Characteristics of Human B-Cell Lymphomas Induced by Epstein-Barr Virus

To identify molecular features of neoplasms associated with EB virus, human peripheral blood lymphocytes (huPBL) were isolated from healthy volunteer donors and were transplanted intraperitoneally into SCID mice, and then huPBL/SCID mice were infected with EB virus. Serum levels of human IgG were measured by unidirectional immunodiffusion assay. Human Alu sequence and EBER-1 in tumor tissues were detected with PCR and in situ hybridization. Immunohistochemical staining was used to examine leukocyte differentiation antigens (LCA, L26, UCHL1, PS1), viral gene products (LMP1, EBNA2, BZLF1) and cellular oncoproteins (p53, C-myc, Bcl-2 and Bax). The experiments showed that tumors developed in 24 of 34 surviving huPBL/SCID mice by EBV infection. Histopathological and immunohistochemical observations demonstrated that all of the induced tumors in SCID mice were malignant lymphomas derived from human B-lymphocytes. In situ hybridization showed that tumor cells had EBV-encoded small RNA-1 (i.e. EBER-1). Alu sequence could be amplified by PCR from human genome of tumor tissues. Immunohistochemistry detected positive staining of BZLF 1-encoded protein in a small population of tumor cells of almost all cases, and positive staining of LMP1 and EBNA2 only in small number of tumor cells. Human IgG could be found in the serum of 12 SCID mice on the 15th day after huPBL engraftment, and then increased with time and with the development of induced tumors in 6 mice. Positive rates of p53, C-myc, Bcl-2 and Bax expression were 83.33%, 100%, 95.83%, 91.67%, respectively, in 24 cases of the EBV-induced lymphomas. The results indicate that molecular lesions associated with the induced B-cell lymphoma involved EBV infection, expression of oncogenic viral genes, and abnormal expression of cellular oncogenes in human xenografts. Human IgG level in the serum of huPBL/SCID mice can be considered as a useful index for tumor development.