Hybrid hybridomas and their use in immunohistochemistry

A normal antibody-producing cell only expresses one antibody, resulting in the well-known phenomenon of allelic exclusion. When two myeloma cells are fused, the derived hybrids are capable of co-dominantly expressing the antibody genes of both parents. Although the respective variable (V) and constant (C) region genes remain expressed in the same cis configuration, heavy and light chains of both parents are scrambled, and hybrid molecules are formed. The same is true when a myeloma and an antibody-producing cell are fused to produce a hybrid myeloma (hybridoma). Fusion therefore allows the production of hybrid immunoglobulin molecules containing two different combining sites. Hybrid molecules of this type retain antigen-binding activity and specificity. Bispecific monoclonal antibodies secreted by hybridomas may have a variety of uses in biology and in medicine. Here we have focused on their application in histochemistry. As an example, we have prepared and tested an anti-somatostatin-anti-peroxidase bispecific antibody. This way of producing hybrid molecules is superior to the production of hybrid antibodies by chemical reconstitution methods because the drastic treatment required for chain separation in the latter is likely to lead to some protein denaturation and loss of antibody activity. Intracellularly synthesized and assembled hybrids do not suffer from this disadvantage. In addition, the recombination of heavy and light chains from different antibody molecules is likely to lead to considerable waste.     

Activation-induced cytidine deaminase turns on somatic hypermutation in hybridomas

The production of high-affinity protective antibodies requires somatic hypermutation (SHM) of the antibody variable (V)-region genes. SHM is characterized by a high frequency of point mutations that occur only during the centroblast stage of B-cell differentiation. Activation-induced cytidine deaminase (AID), which is expressed specifically in germinal-centre centroblasts, is required for this process, but its exact role is unknown. Here we show that AID is required for SHM in the centroblast-like Ramos cells, and that expression of AID is sufficient to induce SHM in hybridoma cells, which represent a later stage of B-cell differentiation that does not normally undergo SHM. In one hybridoma, mutations were exclusively in G*C base pairs that were mostly within RGYW or WRCY motifs, suggesting that AID has primary responsibility for mutations at these nucleotides. The activation of SHM in hybridomas indicates that AID does not require other centroblast-specific cofactors to induce SHM, suggesting either that it functions alone or that the factors it requires are expressed at other stages of B-cell differentiation.     

Cyclosporin A inhibits activation-induced cell death in T-cell hybridomas and thymocytes

One mechanism by which the immune system develops the ability to discriminate self from nonself is the deletion of autoreactive T-cell clones during thymic maturation. The drug cyclosporin A (CsA) has been shown to interfere with this process, allowing the escape of normally 'forbidden' T-cell clones and the appearance of autoimmune disease. Recently, it has been demonstrated that immature thymocytes undergo programmed cell death (apoptosis) upon activation via the T-cell receptor. A similar phenomenon of activation-induced cell death (AICD) has been observed in T-cell hybridomas. Here we show that AICD in T-cell hybridomas in vitro and in thymocytes in vivo is blocked by CsA. Thus, clonal deletion may involve AICD when self-reactive, immature T cells are induced by self antigen, and CsA may cause autoimmunity by interfering with this process.     

抗基因工程人rIFN-γ杂交瘤细胞株的建立

用杂交瘤技术将基因工程人γ－干扰素（ｒＩＦＮ－γ）免疫的Ｂ淋巴细胞与ｓｐ２／０鼠骨髓瘤细胞融合，建立了 ３株抗 ｒＩＦＮ－γ杂交瘤细胞株。这些细胞株经两年多的传代培养仍保持稳定分泌抗体的能力，并与ｒＩＦＮ－γ及新型γ－干扰素呈特异性反应，可用于亲和层析纯化γ－干扰素．     

政府隐匿信息与及时披露信息间的博弈分析

政府在信息处理的过程中面临着“隐匿信息”和“及时披露信息”两种选择 ,将是一种风险与收益的权衡。作者通过建立政府效用函数 ,证明政府在“隐匿信息”和“及时披露信息”的博弈中的最优选择。     

Specific targeted killing of ErbB2 positive breast cancer by retro virus-mediated Immunocaspase-3 secreting T cells

In this study, lmmunocaspase-3 gene was transfected into Jurkat T lymphocytes and the targeted proapoptotic protein Immunocaspase-3 was stably secreted.Its entry to ErbB2 positive SKBr3 breast carcinoma cell line was observed by indirect immunofluorescence staining.Growth of SKBr3 cells was significantly inhibited when they were cultured with medium containing Immunocaspase-3.Next, lmmunocaspase-3 gene was cloned into retrovirus vector pLNCX, which was then transfected into PA317 cells to package. Packaged cells producing high titer pseudoviruses were acquired and the pseudoviruses were harvested to infect PBMCs, which had been stimulated to division. The latter were selected and administered to nude mice bearing SKBr3 tumors through tail vein. The results showed that the treatment contributed to an inhibition of tumor growth and prolonged the lifetime of nude mice bearing SKBr3 tumor.The efficiency of inhibition of tumor reached 73.25%, and the average lifetime of treated nude mice was 80.95% longerthan that of control group. Immunohistochemical examination revealed the exclusive distribution of Immunocaspase-3 proteins only in the tumor tissue samples; and TUNEL assay confirmed the occurrence of apoptosis in tumor calls. Thepresent study suggests that Immunocaspase-3 secreted by T lymphocytes can selectively bind and enter into ErbB2 positive breast cancer cells, where it exhibits a proapoptotic activity and causes tumor suppression in an in vivo tumor model.     

人表皮生长因子（hEGF）基因合成及在枯草杆菌BS9920中分泌表达

采用PCR技术人工合成了一段长约175bp的人表生长因子（hEGF)的基因片段，为了便于克隆，在该片段的5′端设计了Pst I的酶切位点及与pUS186载体signal sequence相连接的碱基部分，在3′端设计了HindⅢ的酶切位点及终止密码子，经DNA分析，合成的片段与已发表的hEGF在序列上完全一致，之后将其克隆至枯草杆菌分泌型质粒载体pUS186上，构建重组载体pUSE并转化一株枯草杆菌突变菌株BS9920感受态细胞，以PCR法快速筛选重组菌落，RIA检测结果表明BS9920阳性转化子能够表达和分泌hEGF。     

纠缠于人与自然人之间--关于法人本质的反思

认清法人的本质首先必须正确理解自然人。自然人不是人，它只不过是法学上的一个拟制的概念。由于实体说和拟制说都存在“自然人就是人”的误区，所以两种学说都须理论上的反思。     

Non-tolerance and autoantibodies to a transgenic self antigen expressed in pancreatic beta cells

Transgenic mice expressing simian virus 40 T antigen under control of the insulin gene regulatory region vary in their response to this protein. Each lineage is characteristically either tolerant to T antigen, or not, in which case autoantibodies arise with high frequency, and lymphocytes infiltrate and disrupt the pancreatic islets. Both non-tolerance and the autoimmune response appear to result from delayed onset of T antigen expression during beta cell development.     

以人为本与相对人类中心主义的一致性

人是自然的存在物，人是人的世界的根本，人是创造人的世界的主体。人类中心主义的出现是人类征服自然和改造自然的结果，也显现了人与自然的矛盾。相对人类中心主义奉行的是互利互惠的准则，体现了以人为本、人与自然协调发展的思想。     

浅析如何将人力资源变为人力资本

现今社会,人力资源已成为被大众认知的名词,原来的人事部也已改称为人力资源部。然而,仅仅将人力做为资源还不够,还应将人力变为资本,使其成为企业的财富,让其为企业所用,并不断增值,给企业创造更多的价值。