The analysis of lymphoid cell differention by using cell lines transformed with a ts mutant of Abelson murine leukemia viurs.

我们根据B淋巴瘤在允许和不允许的温度下分化状态的变化，通过生物学实验成功地获得了Abelson小鼠白血病病毒(A-MuLV)的ts突变株，并通过T病毒前病毒DNA的骨髓集落实验、病灶实验和基因转染实验进一步分析了病毒的活性。结果表明，该病毒具有ts突变病毒的特性，利用该ts突变体，我们建立了几个未成熟的B淋巴瘤，以分析免疫球蛋白(Ig)在分化过程中的表达机制。我们观察到2)VH基因与D@j片段的连接是在Ig重排之前预先确定的，2)在前B细胞阶段合成的u链以未知分子的形式表达在细胞表面(S)。目前尚不清楚这种现象是否是已建立的淋巴瘤所特有的，然而，这一分析提供了关于Ig基因表达编程的新信息，而不是人们认为VH基因是在Ig基因重排阶段重新选择并用于VDJ连接的。另一方面，VH基因是在Ig基因重排阶段被重新选择用于VDJ连接的我们建立了一个新的系统，通过转化包括一个ts变异体在内的病毒来转化胎儿胸腺中的淋巴样细胞。通过使用这个新系统，我们观察到B前体细胞在胎儿胸腺中存储的频率很高。保存胎肝来源的B细胞前体，支持胸腺和胎肝来源的前B细胞淋巴瘤的发生和存活。这一结果为胸腺基质在B细胞发育中的作用提供了新的认识。此外，我们还建立了未成熟T细胞系，其中一种是“双阴性”、CD3+和]阳性细胞，另一种是Thy-1+、AA4.1+、IL2R+细胞。后者可能属于文献中尚未发现的未成熟T细胞系。

We have succeeded in obtaining a ts mutant of Abelson murine leukemia viurs(A-MuLV) through a biologikal assay relying on changes in the differentiation state of B lymphomas at permissive and nonpermissive temperatures.The viral activity was further analysed by bone marrow colony assay, focus assay,and gene transfection assay using proviral DNA of ts virrus. The results confiem that the virus carries theproperty of a ts mutat virus.By using this ts mutant,designated as ts-49,we have established several immature B lymphomas to analyse the mechanism of immunoglobulin(Ig) expression during differentiation. We observed 2)the usage of a VH gene to join toa D@j segment was predetemined prior to the Ig rearrangement,2) u chains, synthesized at the stage of pre-B cells,were expressd on the cell surface as an associated from with unknown molecule(s).It is not known whether the phenomena are only peculiar to established lymphomas,however,the analysis provides new information about the programming of Ig gene expression,in contrast to the esteblished view that VH genes are rendomely selected and used for VDJ joining at the stage of Ig gene rearrangement.On the other hand,we have established a new system to transform lymphoid cells in fetal thymus by transforming viruses including a ts mutant.By using this new system,we observed that B precursors were stored at high frequency in fetal thymus.Fetal thymus carries activity. to store B precursors of fetal liver origin and to support the generation and survivals of pre-B lymphomas of thymic and fetal liver origin.This result leads new insight about the role of thymic stromas on B cell development.In addition,we have establishd immature T cell lines;one is "double negative",CD3+,and]positive cell and antogher is Thy-1+,AA4.1+, IL2R+.The latter may belong toimmature T lineage cells which are nou known in the literature.