Gene Targeted Mice With A Simplified Immune System

描述(由申请人提供)：简化免疫系统克隆选择的基因靶标小鼠要求单个B细胞是单特异性的。等位基因和等位基因排除确保了只有一个功能性重链(H)链和一个功能性轻链(L)基因。虽然人们普遍认为L链的等位基因和同型排斥是通过关闭从基因片段中组装基因的酶来完成的，但已经提出了各种相互竞争的理论来解释H链基因的等位基因排斥。这项建议的目的是评估随机、遗传调节和细胞调节模型对理解免疫球蛋白H链基因座的等位基因排斥的贡献。 因为我们已经获得了一些迹象，即前B细胞群体中含有两个高效重排的H等位基因的细胞，所以我们建议测定具有生殖系H和L基因座的小鼠以及存在预制H和L基因的小鼠的双H产生频率。由于通过免疫荧光可以很容易地区分Mu和Delta等位基因的产物，我们将使用C-Mu等位基因被敲除的小鼠。此外，我们将在B淋巴细胞核移植产生的单克隆性B细胞小鼠身上测试各种假说。在拟议的实验中，来自原始B淋巴细胞的H和L等位基因将被改组，并与生殖系或非功能等位基因相结合。目的是创造代表各种前B细胞和B细胞基因类型的小鼠，并研究各种预先形成的等位基因对胚系或重排等位基因(S)的影响以及与等位基因排斥有关的对B细胞发育的影响。

DESCRIPTION (provided by applicant): Gene-targeted mice with a simplified immune system clonal selection demands that individual B cells be monospecific. Allelic and isotypic exclusion ensure that there is but one functional heavy (H) chain and one functional light (L) chain gene. While there is general agreement that allelic and isotypic exclusion of L chain is accomplished by turning off the enzymes that assemble the genes from gene segments, various competing theories have been proposed to explain allelic exclusion at the H-chain locus. The goal of this proposal is to assess the contributions of the stochastic, genetic regulation, and cellular regulation models to the understanding of allelic exclusion at the immunoglobulin H-chain locus. Because we have obtained some indication that the pre-B-cell population contains cells with two productively rearranged H alleles, we propose to determine the frequency of the double H producers in mice with germ line H and L loci, and in the presence of preformed H and L genes. Because the products of the mu and delta alleles can be easily distinguished by immunofluorescence, we will use mice in which one C-mu allele is knocked out. Furthermore, we will test the various hypotheses in the monoclonal B-cell mouse generated by nuclear transfer from a B lymphocyte. In the proposed experiments, the H and L alleles from the original B lymphocyte will be shuffled and combined with germ line or nonfunctional alleles. The aim is to create mice that represent various pre-B- and B-cell genotypes, and to investigate the effect of the various preformed alleles on the germ line or rearranged allele(s) and on B-cell development as it relates to allelic exclusion.