Kenny J J, O'Connell C, Sieckmann D G, Fischer R T, Longo D L
Program Resources, Inc./DynCorp., National Cancer Institute, Frederick Cancer Research and Development Center, Maryland 21702.
J Exp Med. 1991 Nov 1;174(5):1189-201. doi: 10.1084/jem.174.5.1189.
Flow cytometric analysis of antigen-specific, idiotype-positive (id+), B cell development in transgenic mice expressing a rearranged M167-mu gene shows that large numbers of phosphocholine (PC)-specific, M167-id+ B cells develop in the spleen and bone marrow of these mice. Random rearrangement of endogenous V kappa genes, in the absence of a subsequent receptor-driven selection, should give rise to equal numbers of T15- and M167-id+ B cells. The observed 100-500-fold amplification of M167-id+ B cells expressing an endogenous encoded V kappa 24]kappa 5 light chain in association with the M167 VH1-id transgene product appears to be an antigen driven, receptor-mediated process, since no amplification of non-PC-binding M167 VH1/V kappa 22, T15-id+ B cells occurs in these mu-only transgenic mice. The selection and amplification of antigen-specific, M167-id+ B cells requires surface expression of the mu transgene product; thus, no enhancement of M167-id+ B cells occurs in the M167 mu delta mem-transgenic mice, which cannot insert the mu transgene product into the B cell membrane. Surprisingly, no selection of PC-specific B cells occurs in M167-kappa-transgenic mice although large numbers of B cells expressing a crossreactive M167-id are present in the spleen and bone marrow of these mice. The failure to develop detectable numbers of M167-id+, PC-specific B cells in M167-kappa-transgenic mice may be due to a very low frequency of M167-VH-region formation during endogenous rearrangement of VH1 to D-JH segments. The somatic generation of the M167 version of a rearranged VH1 gene may occur in less than one of every 10(5) bone marrow B cells, and a 500-fold amplification of this M167-Id+ B cell would not be detectable by flow cytometry even though the anti-PC antibody produced by these B cells is detectable in the serum of M167-kappa-transgenic mice after immunization with PC.
对表达重排的M167-μ基因的转基因小鼠中抗原特异性、独特型阳性（id+）B细胞发育进行的流式细胞术分析表明，在这些小鼠的脾脏和骨髓中发育出大量磷酸胆碱（PC）特异性、M167-id+ B细胞。在内源性Vκ基因随机重排且无后续受体驱动选择的情况下，应产生等量的T15-和M167-id+ B细胞。观察到与M167 VH1-id转基因产物相关的、表达内源性编码的Vκ24]κ5轻链的M167-id+ B细胞有100至500倍的扩增，这似乎是一个抗原驱动、受体介导的过程，因为在这些仅表达μ的转基因小鼠中，不与PC结合的M167 VH1/Vκ22、T15-id+ B细胞没有扩增。抗原特异性M167-id+ B细胞的选择和扩增需要μ转基因产物的表面表达；因此，在不能将μ转基因产物插入B细胞膜的M167 μδmem转基因小鼠中，M167-id+ B细胞没有增加。令人惊讶的是，在M167-κ转基因小鼠中没有发生PC特异性B细胞的选择，尽管在这些小鼠的脾脏和骨髓中有大量表达交叉反应性M167-id的B细胞。在M167-κ转基因小鼠中未能发育出可检测数量的M167-id+、PC特异性B细胞，可能是由于VH1与D-JH片段内源性重排期间M167-VH区域形成的频率非常低。重排的VH1基因的M167版本的体细胞产生可能发生在每10^5个骨髓B细胞中不到1个的细胞中，并且即使在用PC免疫后这些B细胞产生的抗PC抗体在M167-κ转基因小鼠的血清中可检测到，这种M167-Id+ B细胞500倍的扩增通过流式细胞术也无法检测到。
