PLASMACYTOMAGENESIS AND LYMPHOCYTE DEVELOPMENT

I. BALB/c小鼠对浆细胞瘤（PCT）诱导高度敏感 使用含有J3 V1逆转录病毒的myc-raf的方案，而DBA/2小鼠 有抵抗力我们以前已经证明，易感性是 与BALB/c B细胞基因型相关。然而，肿瘤诱导 仍然需要先前给药引起的肉芽肿形成 表明需要适当的微环境 肿瘤进展为了研究T细胞在这一过程中的作用， 微环境中，J3 V1用于在裸鼠中诱导肿瘤。B谱系 裸鼠的肿瘤几乎完全是前B或B细胞的表型 PCT很少发生。相反，当肿瘤被诱导时， 在T细胞重建裸鼠中，40%是PCT细胞，60%是B细胞 与未重构的裸细胞中诱导的肿瘤难以区分的肿瘤 小鼠这些结果被解释为表明J3 V1可以转化 早期B谱系细胞，T细胞在免疫应答中不起作用。 转化过程然而，T细胞需要驱动 将B细胞转化为完全分化的抗体分泌血浆 细胞二.目前正在处理PCT的早期发展问题 通过原位杂交研究来评估发育中的克隆性， 肿瘤性病变已经为7个VH家族准备了探针， 与肉芽肿组织的连续切片杂交， 早期病变类似的研究还将 列举与病变发展相关的其他细胞类型， 与肿瘤形成过程相关的细胞微环境。 三.以前的研究表明，原发性浆细胞瘤是 依赖于与基质细胞饲养层的物理接触， 生存和增殖。这种相互作用部分是由 细胞表面分子CD 44，但其他小鼠可用的抗体 细胞表面受体不能抑制粘附。努力查明还 分子参与这种粘附，大鼠单克隆抗体已被 针对从原发部位获得的基质细胞制备 浆细胞生成目前正在对这些抗体进行筛查， 特异性和抑制浆细胞粘附至基质的能力 细胞饲养层。CD 44在肿瘤和正常组织中的作用 发展是一个重要的生物学问题。审查 在体内功能的CD 44，我们正在产生的过程中的CD 44 敲除小鼠已经分离出一系列基因组克隆， 正在分析外显子的位置一个选择的外显子将 被新霉素抗性基因中断， 引入胚胎干细胞以产生嵌合体的等位基因 小鼠

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.