Gene Targeted Mice With A Simplified Immune System

描述（由申请人提供）：具有简化免疫系统的基因靶向小鼠克隆选择要求单个B细胞是单特异性的。等位基因和同型排斥确保只有一个功能重(H)链和一个功能轻(L)链基因。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链位点的等位基因排斥。本提案的目的是评估随机、遗传调控和细胞调控模型对理解免疫球蛋白h链位点等位基因排斥的贡献。

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.