Clarke S, McCray S
Department of Microbiology and Immunology, University of North Carolina, Chapel Hill 27599.
J Immunol. 1991 Jan 1;146(1):343-9.
Ig kappa-chain gene rearrangement results in the displacement or loss of the DNA immediately 5' of Jk. This retained DNA is found on a different size fragment than in the germline (a reciprocal fragment), and contains the reciprocal joint of rearranged Vk and Jk genes, the back-to-back fusion of the heptamer/nonamer recombination signals. B cells of independent origin rarely have reciprocal fragments of the same size. However, we report that 9 of 15 B cell hybridomas of independent origin have reciprocal fragments of the same size (8-kb BamHI fragments) unrelated to their productive rearrangements. An 8-kb reciprocal fragment has also occurred on about 25% of the kappa alleles of normal splenic B cells. We find that the reciprocal fragments in two of these hybridomas contain the reciprocal joints of Jk1 genes and different Vk8 genes. In addition, we find that at least 8 of the 12 Jk4 or Jk5 expressing hybridomas have undergone double recombinations on their productive kappa alleles. The implications of these findings on the high frequency of 8-kb reciprocal rearrangements and on Vk rearrangement are discussed.
Ig κ链基因重排导致Jk 5'端紧邻的DNA发生位移或缺失。这种保留的DNA存在于与种系不同大小的片段上（一个相互片段），并包含重排的Vk和Jk基因的相互连接点，即七聚体/九聚体重组信号的背对背融合。独立起源的B细胞很少有相同大小的相互片段。然而，我们报告称，15个独立起源的B细胞杂交瘤中有9个具有与其有效重排无关的相同大小的相互片段（8kb的BamHI片段）。在正常脾B细胞的约25%的κ等位基因上也出现了一个8kb的相互片段。我们发现，其中两个杂交瘤中的相互片段包含Jk1基因和不同的Vk8基因的相互连接点。此外，我们发现，在12个表达Jk4或Jk5的杂交瘤中，至少有8个在其有效的κ等位基因上发生了双重重组。讨论了这些发现对8kb相互重排的高频率以及对Vk重排的影响。
