范文实例：
以下为一毕业论文的范文，供同学们书写时候进行格式参考。
中文摘要
HLA 1分子在胃癌中的表达机制
摘 要
目的：肿瘤细胞表达HLA (human leukocyte antigen) 分子是激发肿瘤抗原特异性CTL (cytotoxic T lymphocytes) 进行肿瘤免疫治疗的关键，其中肿瘤细胞中HLA I类分子表达异常是肿瘤逃逸机体免疫监视的重要机制之一。本研究探讨胃癌组织中HLA I类抗原及相关分子的表达情况，检测HLA基因区域微卫星DNA的杂合性丢失 (loss of heterozygosity; LOH)，并分析它们的相关性。为研究胃癌中HLA I类分子的异常表达机制提供理论依据。
方法：首先应用4种HLA相关分子单抗，采用免疫组化的方法（ABC法）检测胃癌石蜡组织标本中HLA I类及相关分子的表达情况，统计分析各分子表达与临床分期及病理分级的相关性。同时应用5种HLA I类分子相关抗体，采用冰冻切片免疫组化的方法，检测新鲜胃癌组织中HLA I类分子的表达情况，并应用微卫星多态性分析技术检测胃癌组织中6p HLA及15q β2m (β2-microglobulin) 基因区域的LOH。
结果：在组织学水平，185例胃癌石蜡切片中HLA I类分子表达异常，HLA I类分子B/C位点下调率41%，丢失率22%；A位点下调率32%，丢失率19%。其中B/C位点的表达与肿瘤分期相关，且随着胃癌分化程度的降低逐渐下调。20例淋巴结转移灶中，有8例（40%）HLA I类分子表达低于原发癌。与癌旁组织比较，50例新鲜胃癌组织冰冻切片中HLA I类分子表达下调显著（P<0.05），其中重链各分子与HLA I类分子表达下调密切相关，尤以HLA-B/C位点显著 （P<0.05 rs=0.8236）；应用微卫星多态性分析技术发现，胃癌组织HLA基因区域发生LOH的频率为18.3%，β2m基因发生LOH的频率为14.5%。HLA区域内各位点LOH的频率分别为：D6S1618,16%；D6S291,12%；D6S273,15%；D6S265,15%；D6S105,34%；D6S276,16%。所研究病例未见有6号染色体完全丢失现象的存在。与β2m基因紧密相邻的两个微卫星位点，其LOH频率分别为：D15S-126，18%；D15S-209，11%。其中与HLA I类分子重链基因紧密相邻的D6s-105位点LOH频率最高（34.2%）。
结论：在胃癌组织中，存在着明显的HLA I类分子表达下调或缺失，且重链各分子与HLA I类分子表达下调密切相关（P<0.05），淋巴结转移病例HLA I类分子表达下调或丢失高于原发癌。通过HLA I类各分子的表达与相应位点LOH的对比分析，大部分HLA I类各分子与癌旁组织相比表达一致或增强者未发生LOH，表达下调或阴性者则发生了LOH，特别是与HLA重链基因区域紧密相邻的微卫星位点发生LOH的频率最高，说明HLA重
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中文摘要
链基因区域微卫星DNA的LOH可能影响了HLA重链各分子的表达，并进一步影响了HLA I类分子在细胞表面的完整性表达。本研究显示HLA重链基因区域的LOH是影响胃癌组织HLA I类分子异常表达的重要机制之一。
关键词：胃癌；HLA I类抗原；免疫组化；杂合性丢失
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英文摘要
The mechanism of HLA class I molecules expressed abnormally
in gastric cancer
ABSTRACT
Objective： Pathogenesis of tumors and anti-tumor immune response in host has attracted a lot of attention. HLA class I molecules play a critical role in the antigen processing, presenting and special recognition of tumor cells by cytotoxic T lymphocytes (CTL). There is a general consensus that the abnormal expression of HLA class I molecules reflects the escape mechanism of tumor cells and it is pivotal to excite tumor antigen-special CTL to carry through immune therapy for the expression of HLA class I molecules in tumor cells surface. We discussed the expression of HLA class I molecules in gastric cancer tissues and detected the LOH of microsatellite DNA at HLA gene region, which provided a theory basis for studying the abnormal expression mechanism of HLA class I molecules in gastric cancer.
Methods：185 formalin-fixed paraffin-embeded tumor tissues, 22 corresponding autologous normal specimens and 20 lymphnode metastatic cases were tested using 4 monoclonal antibodies (mAbs) by meanings of immunohistochemical technique (ABC method); 50 OCT-embeded fresh gastric cancer and corresponding normal tissues, which were made into freezing slice, were tested applying 5 monoclonal antibodies (mAbs) by the same method, and analyzed of the LOH frequency at HLA (6p) and β2m (15q) gene region by microsatellite polymorphic analysis technology.
Results：HLA class I antigens were obviously downregulated (A locus 41%, B/C locus 32%) and lost (A locus 22%, B/C locus 19%) in 185 formalin-fixed paraffin-embeded gastric cancer tissues, and the downregulated expression of B/C locus is significantly associated with pathological grade （p<0.05）. In 20 lymphnode metastatic cases, 8 cases show downregulated expression of HLA class I antigens compared with the primary tumor. HLA class I antigens were also obviously downregulated in 50 OCT-embeded fresh gastric cancer compared with corresponding normal tissues (P<0.05). The downregulated expression is correlated with heavy chain molecules especially HLA-B/C locus. It was accordant to the results of the
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英文摘要
paraffin-embeded tissues. The LOH frequency of HLA gene region is 18.3% in gastric cancer and the highest is D6s105 (34.2%). The individual LOH frequency for the six intra-MHC markers was: D6S1618, 16%; D6S291, 12%; D6S273, 15%; D6S265, 15%; D6S105, 34%; D6S276, 16%. It was not seen about loss of the whole chromosome 6 in the studied samples. The LOH frequency of β2m gene is 14.5%. D15S-126 and D15S-209, next toβ2m, was 18% and 11% respectively.
Conclusion：expression of HLA class I antigens is obviously downregulated in gastric cancer, and which is more obvious in lymphnode metastatic cases than the primary tumor. The downregulation is correlated with heavy chain molecules（P<0.05 ）. In order to elucidate the mechanism, we extended our study to detect LOH (loss of heterozigosity) of microsatellite DNA at HLA gene region in gastric cancer and compared HLA class I molecules expression with LOH in corresponding locus, the results indicate that the majority of the tumors with positive expression of HLA class I have no allelic loss at all informative loci, the tumors with weak or negative expression show LOH for at least one locus. However, it can be concluded that LOH of HLA class I heavy chains was one of the mechanisms that lead to abnormally expression of HLA class I molecules and provided the tumor cells with a way to escape immune surveillance in gastric cancer. But, it is not benefit for T-cell based treat of tumor.
Key words： gastric cancer; HLA class I; LOH; Immunohistochemistry
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