Molecular cloning and polymorphism of major histocompatibility complex class I genes from grass carp (Ctenophayngodon idellus)

In order to clarify the molecular sequences,allelic polymorphism and the tertiary structure of grass carp (Ctenophayngodon idellus) MHC class I,and to further study their relationship with disease resistances,grass carp MHC class I gene (Ctid-MHC I) was cloned from a cDNA library and the allelic polymorphism in the population was investigated.The results showed that most of the variations exist in the peptide-binding domain (PBD) and high polymorphism was identified in the Ctid-MHC I allelic genes from 12 individuals.Based on the genetic distance,Ctid-MHC class I can be classified into 6 types (from Ctid-MHC I-UA to Ctid-MHC I-UF) which were subdivided into 9 lineages (from A to I).Comparison of the Ctid-MHC I among animals and humans showed that the key amino acids of the peptide binding sites are conserved.Analysis of the tertiary structure of the PBD between Grass carp and human crystallographic data of HLA-A2,the variation with insertion or deletion was found in eight regions (A～H).The phylogenetic tree of MHC class I indicates the evolution of MHC class I among grass carp,fish,amphibian,birds,higher vertebrates and humans.     

The macromolecular peptide-loading complex in MHC class I-dependent antigen presentation

A challenging task for the adaptive immune system of vertebrates is to identify and eliminate intracellular antigens. Therefore a highly specialized antigen presentation machinery has evolved to display fragments of newly synthesized proteins to effector cells of the immune system at the cell surface. After proteasomal degradation of unwanted proteins or defective ribosome products, resulting peptides are translocated into the endoplasmic reticulum by the transporter associated with antigen processing and loaded onto major histocompatibility complex (MHC) class I molecules. Peptide-MHC I complexes are transported via the secretory pathway to the cell surface where they are then inspected by cytotoxic T lymphocytes, which can trigger an immune response. This review summarizes the current view of the intracellular machinery of antigen processing and of viral immune escape mechanisms to circumvent destruction by the host. Received 4 October 2005; received after revision 19 November 2005; accepted 24 November 2005     

干扰素-γ对母胎界面免疫调控的影响

人类和其他哺乳动物的妊娠过程是自然界中存在的一种同种半异体移植免疫耐受模型，近来的研究发现母胎界面上表达的主要组织相容性复合体（MHC）分子有重要作用，经典的和非经典的MHC I/II类抗原表达在妊娠过程中是时空动态变化的，维持妊娠的正常进行.生理剂量的干扰素-γ（IFNγ）是妊娠必需的细胞因子之一，而超过生理剂量的IFNγ则会直接导致流产.IFNγ影响妊娠的机制是多方面的，主要通过调节母胎界面MHC抗原的表达.与此同时，IFNγ下调在妊娠过程中发挥多种生物学功能的细胞因子IL-1β和TGFβ1的表达；促进母胎界面细胞凋亡水平；抑制孕酮的分泌.超生理剂量IFNγ可通过这些作用最终导致母胎界面局部免疫微环境调控失衡，妊娠失败.文中着重介绍近年来母胎界面免疫调控及IFNγ对其作用机制的研究进展.     

卡托普利和肾切除对肾性高血压大鼠左室心肌MHC基因转录变化的影响

用二肾一夹（２ＫＩＣ）肾性高血压大鼠模型，探讨心肌肥厚发生和逆转以及肌球蛋白重链（ｍｙｏｓｉｎｈｅａｖｙｃｈａｉｎ，ＭＨＣ）基因表达的改变。结果表明：１）２ＫＩＣ肾性高血压大鼠术后第２～１２周，动脉血压持续升高、左室重量／体重（ＬＶＷ／ＢＷ）明显升高、左心室α－ＭＨＣ基因表达明显减弱、β－ＭＨＣ基因表达明显增强；２）在术后第４周给予血管紧张素转换酶抑制剂卡托普利和术后第８周切除肾动脉狭窄侧肾脏可使２ＫＩＣ肾性高血压大鼠动脉血压下降、左心室肥厚发生逆转、抑制左心室α－ＭＨＣ基因表达减弱和β－ＮＨＣ基因表达增强。这些结果提示在２Ｋ１Ｃ肾性高血压中，动脉血压升高是左心室肥厚、左心室肌球蛋白ＭＨＣ基因表型转换的重要因素；肾素———血管紧张素系统可能参与２ＫＩＣ肾性高血压过程中的心肌肥厚和ＭＨＣ基因表型的转移。     

Short-range linkage relationships, genomic organisation and sequence comparisons of a cluster of five HSP70 genes in Fugu rubripes

Twelve cosmids containing sequences resembling genes encoding members of the 70-kDa heat-shock protein family, HSP70, have been isolated from Fugu rubripes. They can be broadly divided into three groups of overlapping cosmids. Restriction analysis and sequencing of one set of five cosmids have revealed five intronless Fugu HSP70 genes spanning 42 kb, arranged in a combined head-to-head, tail-to-tail and head-to-tail orientation. The levels of DNA and amino acid identity are very high with respect to one another, and are most similar to HSP70 sequences linked to the major histocompatibility complex (MHC) region in other species. Putative heat-shock consensus elements are identified. Non-HSP70 sequences with homology to known genes have been found physically linked to this Fugu HSP70 cluster: the Drosophila melanogaster SOL gene, the Drosophila melanogaster nemo gene, the Caenorhabditis elegans T17E9.1 gene and the sequence encoding the serine protease domain. The linkage relationships described here so far bear no resemblance to those of HSP70 in other organisms. Convergence of mammalian HSP70 and MHC class I and II loci probably occurred after fish had diverged. Received 17 November 1998; received after revision 25 February 1999; accepted 26 February 1999     

Human peripheral blood monuclear cells transfected with messenger RNA stimulate antigen-specific cytotoxic T-lymphocytes in vitro

The efficiency of test vaccines needs to be evaluated by quantification of the triggered cellular immune response. Usually, for these assays, autologous target cells expressing the vaccine antigen are required. In the context of messenger RNA (mRNA)-based vaccinations, the target cells used for the read-out are mRNA-transfected monocyte-derived dendritic cells (Mo-DCs). Their production typically requires samples of 100 ml blood from the patients, and limits the number of assays that can be performed. We show here that fresh peripheral blood mononuclear cells (PBMCs) can be transfected with mRNA by electroporation. Such cells are as efficient as mRNA-transfected Mo-DCs for their ability to activate memory T cells in vitro. Thus, mRNA-transfected PBMCs are a convenient replacement of mRNA-transfected Mo-DCs for the in vitro monitoring of natural or vaccine-induced immune responses.Received 17 February 2005; received after revision 1 May 2005; accepted 7 Juni 2005     

Modeling the MHC class I pathway by combining predictions of proteasomal cleavage,TAP transport and MHC class I binding

Epitopes presented by major histocompatibility complex (MHC) class I molecules are selected by a multi-step process. Here we present the first computational prediction of this process based on in vitro experiments characterizing proteasomal cleavage, transport by the transporter associated with antigen processing (TAP) and MHC class I binding. Our novel prediction method for proteasomal cleavages outperforms existing methods when tested on in vitro cleavage data. The analysis of our predictions for a new dataset consisting of 390 endogenously processed MHC class I ligands from cells with known proteasome composition shows that the immunological advantage of switching from constitutive to immunoproteasomes is mainly to suppress the creation of peptides in the cytosol that TAP cannot transport. Furthermore, we show that proteasomes are unlikely to generate MHC class I ligands with a C-terminal lysine residue, suggesting processing of these ligands by a different protease that may be tripeptidyl-peptidase II (TPPII).Received 26 November 2004; received after revision 4 February 2005; accepted 4 March 2005S. Tenzer and B. Peters contributed equally to this work.     

人类及部分实验动物MHC-DRB3.2基因核苷酸序列同源性分析

目的研究人类及部分实验动物DRB3.2基因核苷酸序列的同源性。方法利用PCR技术扩增得到牛的DRB3.2基因片段,并测定其核苷酸序列;从GenBank中下载人类、猕猴、绵羊、山羊、猪的相应基因片段;利用DNAMAN软件进行碱基组成分析、同源性分析和构建分子进化树。结果所分析的物种该基因片段大小为267bp,没有发现碱基的缺失以及插入现象;A、T、G、C四种碱基以及G+C的含量在不同物种之间相差较小。就某种动物来说,G的含量最高,T的含量最低,G+C的含量要明显高于A+T含量;人类与猕猴、绵羊、山羊、牛、猪的同源性分别为91.8%、82.8%、82.4%、81.3%、81.6%。结论不同物种MHC-DRB3.2基因核苷酸序列的同源性都比较高;在研究人类有些疾病时,猕猴是其它实验动物不可替代的;DRB3.2基因是研究生物进化和系统发育分析的一个理想遗传标记。     

脑内免疫炎症的发生机制

中枢神经系统神经元退行性变过程中表达主要组织相容性分子、黏附分子和补体受体,并产生多种细胞因子,从而引发脑内的免疫炎症反应。     

实验性癫痫大鼠MHC分子的表达

目的 证明癫痫的免疫学发病机制。方法 采用MHC McAb免疫组织化学染色。结果 实验性癫痫大鼠大脑海马锥状细胞层可见到NHC-Ⅰ，NHC-Ⅱ类分子的表达。结论 实验性癫痫大鼠大脑海马硬化发生过程中，存在着免疫反应发生。