A Vh gene that blocks development of follicular B cells

描述（由申请人提供）：一种不能促进卵泡B细胞发育的VH基因。我们通过将来自2个抗纵火酸杂交瘤的VH基因引入内源性Igh基因座的自然位置（VH敲入小鼠），产生了新的小鼠品系。其中1个品系名为HKI65，含有一个缺乏体细胞突变的VH基因。该VH基因可以单独促进B1， B2和边缘区（MZ） B细胞的正常发育，当它存在于另一个等位基因（JHD）上失活的JH位点时。与此形成鲜明对比的是，在另一个VH敲入蛋白/JHD系（称为HKI71）中，VH基因与HKI65系只相差8个氨基酸替换，B2细胞基本缺失，B1细胞在腹膜中存在，接近正常水平，脾脏中的大多数B细胞为MZ表型。对hki71小鼠成体骨髓B细胞发育的初步分析表明，在B前发育阶段或前后存在严重阻滞。对HKI71/JHD小鼠的进一步研究有望为调控MZ B细胞发育的因素提供新的见解。然而，为了使这种未来的研究得到明确界定，需要更详细的初步数据。特别是，B淋巴系统缺陷的性质需要研究。此外，由于MZ B细胞被认为在外周具有扩张和自我更新的能力，因此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。在本提案中，描述了将解决这些问题的两个重点具体目标。

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.