A Vh gene that blocks development of follicular B cells

描述(申请人提供)：一种不能促进滤泡B细胞发育的VH基因。我们通过将来自2个抗阿索酸杂交瘤的VH基因导入内源性IgH基因座的一个自然位置(VH“敲门”小鼠)，产生了新的小鼠品系。其中一株名为HKI65，含有一种缺乏体细胞突变的VH基因。这个VH基因单独可以促进B1、B2和边缘带(MZ)B细胞的正常发育，当它存在于另一个等位基因(JHD)上的JH失活座位的背景下时就表明了这一点。与之形成鲜明对比的是，在另一株VH Huckin/JHD株(命名为HKI71)中，VH基因与HKI65株的VH基因仅有8个氨基酸替换，其中B2细胞基本上缺失，B1细胞在腹膜中的存在接近正常水平，而脾中的大多数B细胞具有MZ表型。对HKI71小鼠成年骨髓B细胞发育的初步分析表明，在发育的前B阶段或大约B前阶段，B细胞发育严重受阻。对HKI71/JHD小鼠的进一步研究有望为调节MZ B细胞发育的因素提供新的见解。然而，为了使这类未来的研究得到明确的定义，需要更详细的初步数据。特别是，B淋巴系缺陷的性质需要调查。此外，由于MZ B细胞被认为具有在外周扩张和自我更新的能力，HKI71/JHD小鼠中MZ B细胞的优势是否源于HKI71/JHD小鼠发育过程中继发于B淋巴细胞减少状态的事件需要解决。在这份提案中，描述了将解决这些问题的两个有重点的具体目标。

DESCRIPTION (provided by applicant): A VH gene that fails to promote development of follicular B cells. We have generated novel lines of mice by introducing the VH genes from 2 anti-arsonate hybridomas into a natural location in the endogenous Igh locus (VH "knockin" mice). 1 of these lines, called HKI65, contains a VH gene that lacks somatic mutations. This VH gene can alone promote normal development of B1, B2 and marginal zone (MZ) B cells, as shown when it is present in the context of an inactivated JH locus on the other allele (JHD). In striking contrast, in another VH knockin/JHD line (termed HKI71) in which the VH gene differs from that in the HKI65 line by only 8 amino acid substitutions, B2 cells are essentially absent, B1 cells are present at near normal levels in the peritoneum, and most B cells in the spleen are of the MZ phenotype. Preliminary analysis of adult bone marrow B cell development in HKI71mice indicates a severe block at or about the pre-B stage of development. Further studies of HKI71/JHD mice promise to provide new insights into the factors that regulate the development of MZ B cells. However, to allow such future studies to be clearly defined, more detailed preliminary data are required. In particular, the nature of the defect in B lymphopoiesis needs to be investigated. In addition, since MZ B cells are thought to have the ability to expand and self-renew in the periphery, whether the predominance of MZ B cells in HKI71/JHD mice results from events secondary to a state of B lymphopenia during the development of HKI71/JHD mice needs to be addressed. In this proposal, 2 focused specific aims are described that will address these issues.