PLASMACYTOMAGENESIS AND LYMPHOCYTE DEVELOPMENT

I.BALB/c小鼠对浆细胞瘤(PCT)的诱导高度敏感 在DBA/2小鼠体内使用含有J3V1逆转录病毒的myc-raf 是有抵抗力的。我们之前已经证明了易感性是 与BALB/c B细胞基因相关。然而，肿瘤诱导 仍然需要前一次给药引发的肉芽肿形成 表明需要一个适当的微环境 治疗肿瘤进展。为了研究T细胞在这一过程中的作用 微环境J3V1诱发裸鼠肿瘤。B血统 裸鼠体内肿瘤的表型几乎完全是前B细胞或B细胞 PCT很少发生。相反，当诱发肿瘤时 在T细胞重组裸鼠中，40%是PCT细胞，60%是B细胞 与未经重组的裸体诱导的肿瘤难以区分 老鼠。这些结果被解释为表明J3V1可以转化为 早期的B系细胞和T细胞在 转型过程。然而，驾驶时需要T细胞 将B细胞转化为完全分化、分泌抗体的血浆 细胞。二.目前正在处理PCT的早期开发问题 通过原位杂交研究评估发育过程中的克隆性 肿瘤损伤。已经准备了7个VH家庭的探测器，并 与肉芽肿组织的连续切片杂交，其中包含 可能是早期病变。类似的研究还将 列举与正在发生的皮损相关的其他细胞类型以确定 细胞微环境与这种肿瘤过程相关的细胞微环境 先前的研究表明，原发性浆细胞瘤是 取决于与基质细胞饲养层的物理接触 生存和繁殖。这种相互作用在一定程度上是通过 细胞表面分子CD44，但可用于其他小鼠的抗体 细胞表面受体不能抑制黏附。要确定其他 参与这种黏附的分子，大鼠的单抗已经 以从原发部位获得的基质细胞制备 浆细胞瘤发育。目前正在对这些抗体进行筛查 抑制浆细胞与基质黏附的特异性和能力 细胞饲养层。CD44在肿瘤和正常组织中的作用 发展是一个涉及重大生物学利益的问题。要检查 在体内CD44的功能我们正在产生CD44的过程中 基因敲除老鼠。已经分离了一系列基因组克隆，并正在 目前正在分析外显子位置。然后，选定的外显子将 被新霉素抗性基因和失活的 将等位基因导入胚胎干细胞产生嵌合体 老鼠。

I. BALB/c mice are highly susceptible to plasmacytoma (PCT) induction protocols using the myc-raf containing J3V1 retrovirus while DBA/2 mice are resistant. We have previously demonstrated that susceptibility is associated with the BALB/c B cell genotype. However, tumor induction still requires granuloma formation initiated by the prior administration of pristane indicating the necessity for an appropriate microenvironment for neoplastic progression. To examine the role of T cells in this microenvironment, J3V1 was used to induce tumors in nude mice. B lineage tumors in nude mice were almost exclusively pre-B or B cell by phenotype with PCT's occurring only rarely. In contrast, when tumors were induced in T cell reconstituted nude mice, 40% were PCT's and 60% were B cell tumors indistinguishable from those induced in unreconstituted nude mice. These results are interpreted to indicate that J3V1 can transform early B lineage cells and that T cells play no role in the transformation process. T cells are, however, required to drive transformed B cells into fully differentiated, antibody secreting plasma cells. II. The early development of PCT's is currently being addressed by in situ hybridization studies to assess clonality of developing neoplastic lesions. Probes have been prepared to 7 VH families and have been hybridized to serial sections from granulomatous tissue containing putative early stage lesions. Similar studies will additionally enumerate other cell types associated with developing lesions to define the cellular microenvironment associated with this neoplastic process. III. Previous studies have demonstrated that primary plasmacytomas are dependent on physical contact with stromal cell feeder layers for survival and proliferation. This interaction is mediated, in part, by the cell surface molecule CD44, but available antibodies to other mouse cell surface receptors fail to inhibit adhesion. To identify additional molecules involved in this adhesion, rat monoclonal antibodies have been prepared against stromal cells obtained from the primary site of plasmacytomagenesis. These antibodies are currently being screened for specificity and ability to inhibit adhesion of plasma cells to stromal cell feeder layers. The role of CD44 in both neoplastic and normal development is a question of major biological interest. To examine the in vivo function of CD44 we are in the process of generating CD44 knockout mice. A series of genomic clones have been isolated and are currently being analyzed for exon locations. A selected exon will then be interrupted with the neomycin resistance gene and the inactivated allele introduced into embryonal stem cells for generation of chimeric mice.