ROLE OF KILLER INHIBITORY RECEPTOR GENES IN AUTOIMMUNE AND INFECTIOUS DISEASES

自然杀伤(NK)细胞是一组独特的淋巴细胞，通过NK细胞表面一组极其不同的受体识别HLA分子的机制，参与对外来细胞或感染细胞的监视和杀伤。杀伤细胞抑制受体基因(KIRS)与其他相关基因一起定位于染色体19q13.4。其中一些基因编码识别人类白细胞抗原-C配体的分子，而另一些基因则结合人类白细胞抗原-A和-B分子。与第I类细胞毒性T淋巴细胞(CTL)对肽的识别不同，NK细胞破坏缺乏第I类表达的靶点，它们被细胞表面第I类识别所抑制。NK细胞在防御病毒方面发挥着重要作用，病毒抑制I类分子的表达，从而避免CTL的识别。例如，HIV-1下调了细胞表面的HLA-A和-B分子(而不是-C)的表达，而解释某些HLA型个体快速发展为艾滋病的一种机制可能涉及NK细胞活性的改变。Nef通过下调HLAA和HLAB来降低CTL活性，同时通过不影响HLAC的表达来降低NK活性，从而有效地削弱宿主防御系统。也有证据表明人类乳头瘤病毒(HPV)下调了I类基因的表达。我们开发了KIR基因的分子分型技术，以研究这些基因在自身免疫(银屑病关节炎、强直性脊柱炎和多发性硬化症)和感染性疾病(与HIV-1、丙型肝炎病毒和乙肝病毒相关的疾病)中的潜在作用。KIR基因复合体的单倍型在存在的KIR基因数量上存在差异，其中一些基因具有轻微的多态。我们最初的方法是确定每个KIR基因的存在或不存在，但我们也开始开发每个基因座的等位基因分型方法。我们的方法包括聚合酶链式反应(聚合酶链式反应)扩增与每个基因座的特异性引物(聚合酶链式反应-聚合酶链式反应-聚合酶链式反应)。我们对所有的基因座都使用相同的扩增条件，大大提高了分析的效率。DRB1基因第三内含子的796个碱基片段的内对照引物也包含在每个PCR反应中。为了确认特定基因座的存在或不存在，为每个基因座设计了两套引物。整个打字方案可以以96孔格式执行，从而为半自动化提供了一种潜在的手段。几种KIR基因产物对HLA-C分子的识别使我们推测，在从与HLA-C相关的疾病获得的数据集中，人类白细胞抗原和KIR基因之间的协同作用可能是最明显的。人类白细胞抗原与自身免疫性疾病的关系似乎没有感染性疾病那么复杂。因此，我们已经确定了一组患有前列腺特异性抗原(PSA)的个体，这是一种已被证明与HLA-CW*06相关的疾病。PSA组中CW*06的个体的KIR基因频率也将被确定，并与对照数据集进行比较。目前正在对这些数据进行分析。我们还开始使用一组强直性脊柱炎患者和一组HIV-1感染者的样本对这些基因进行分型。杀伤细胞抑制受体基因在艾滋病中的作用--自然杀伤细胞、杀伤抑制受体、人类组织、体液、细胞等。

Natural killer (NK) cells are a unique group of lymphocytes involved in surveillance and killing of foreign or infected cells through a mechanism involving recognition of HLA molecules by an extremely diverse set of receptors on the NK cell surface. The killer inhibitory receptor genes (KIRs) map to chromosome 19q13.4 along with other related genes. Some of these genes encode molecules that recognize HLA- C ligands, whereas others bind HLA-A and -B molecules. In contrast to cytotoxic T lymphocyte (CTL) recognition of peptide as presented by class I, NK cells destroy targets that lack expression of class I, and they are inhibited by recognition of class I on the cell surface. NK cells play an important role in defense against viruses that inhibit class I molecule expression and thereby avoid recognition by CTL. For example, HIV-1 downregulates cell surface expression of HLA-A and -B molecules (but not -C) and one mechanism to explain rapid progression to AIDS in individuals with certain HLA types may involve alteration of NK cell activity. The host defense system may be crippled effectively by reducing CTL activity through Nef downregulation of HLA-A and -B, along with curtailment of NK activity by not affecting the expression of HLA-C. Evidence for downregulation of class I by human papilloma virus (HPV) has also been reported. We have developed a molecular typing technique for the KIR genes in order to study potential effects of these genes on autoimmune (psoriatic arthritis [PSA], ankylosing spondylitis and multiple sclerosis) and infectious diseases (those associated with HIV-1, hepatitis C virus and hepatitis B virus). Haplotypes of the KIR genes complex vary in the number of KIR genes present and some of the genes are slightly polymorphic. Our initial approach has been to determine presence or absence of each KIR gene, but we have also begun to develop means for typing alleles at each locus. Our protocol involves polymerase chain reaction (PCR) amplification performed with primers specific for each locus (PCR-SSP). We use the same amplification conditions for all loci, greatly enhancing the efficiency of the assay. Internal control primers for a 796-bp fragment of the third intron of DRB1 are also included in each PCR reaction. In order to confirm the presence or absence of a particular locus, two sets of primers have been designed for each locus. The entire typing protocol can be performed in a 96-well format, thereby providing a potential means for semi-automation. Recognition of HLA-C molecules by several of the KIR gene products led us to speculate that synergistic interactions between HLA and KIR genes might be most obvious in data sets obtained from diseases associated with HLA-C. HLA associations with autoimmune diseases appear to be less complex than those involving infectious diseases. Thus, we have typed a group of individuals with (PSA), a disease that has been shown to be associated with HLA-Cw*06. Frequencies of the KIR genes among individuals in the PSA group who are Cw*06 will also be will determined and compared to a control data set. This data is being analysed presently. We have also begun to type these genes using samples from a group of patients with ankylosing spondylitis and a group of HIV-1-infected individuals. Role of Killer Inhibitory Receptor Genes in AIDS - Natural killer cells, Killer inhibitory receptors, HLA, - Human Tissues, Fluids, Cells, etc.