A Vh gene that blocks development of follicular B cells

描述（由申请人提供）：一种不能促进滤泡B细胞发育的VH基因。我们已经通过将来自2个抗胂酸盐杂交瘤的VH基因引入内源性Igh基因座中的天然位置（VH“敲入”小鼠）来产生新的小鼠品系。其中1个细胞系，称为HKI 65，含有缺乏体细胞突变的VH基因。该VH基因可单独促进B1、B2和边缘区（MZ）B细胞的正常发育，如当其存在于另一等位基因（JHD）上的失活JH基因座的情况下所示。与此形成鲜明对比的是，在另一种VH敲入/JHD系（称为HKI 71）中，其中VH基因与HKI 65系中的VH基因仅相差8个氨基酸取代，B2细胞基本上不存在，B1细胞以接近正常水平存在于腹膜中，并且脾中的大多数B细胞具有MZ表型。对HKI 71小鼠成年骨髓B细胞发育的初步分析表明，在发育的前B阶段或其附近存在严重阻滞。对HKI 71/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，为了明确界定今后的研究，还需要更详细的初步数据。特别是，需要研究B淋巴细胞生成缺陷的性质。此外，由于MZ B细胞被认为具有在外周中扩增和自我更新的能力，因此需要解决HKI 71/JHD小鼠中MZ B细胞的优势是否是由HKI 71/JHD小鼠发育期间B淋巴细胞减少状态继发的事件引起的。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.