Rearrangement and selection in the developing Vkappa repertoire of the mouse: an analysis of the usage of two Vkappa gene segments.
Detailed analysis of the rearrangement and expression of two mouse Vkappa genes has been used to examine B cell repertoire development. The Vkappa1-A gene is used by a large proportion (9.6%) of splenic B cells in the adult primary repertoire, whereas the Vkappa22 gene is used at a much lower frequency (0.16%). Consistent with these results, quantitative PCR (Q-PCR) assays revealed that the number of splenic B cells with rearranged Vkappa1-A genes is much greater than the number with rearranged Vkappa22 genes. Q-PCR was also performed on both normal bone marrow pre-B cells and transformed pre-B cells induced to rearrange their kappa loci at high frequency. In contrast to splenic B cell rearrangements, the numbers of Vkappa1-A and Vkappa22 rearrangements in pre-B cells differ by only two- or threefold, suggesting that the intrinsic rearrangement frequencies of these two Vkappa genes are not significantly different. Further evidence of disproportionate selection was obtained by comparing the percentages of productive rearrangements amplified from genomic splenic DNA. Sequence analysis showed 84% (37 of 44) of the Vkappa1-A rearrangements but only 57% (29 of 51) of the Vkappa22 rearrangements to be in-frame. Together these results suggest that B cells expressing Vkappa1-A-encoded light chains are preferentially selected either in the periphery or in the transition from pre-B to B cell. Sequence data also reveal a surprisingly restricted diversity of VJ junctions, apparently due to biases introduced by the rearrangement mechanism.
Whitcomb
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EA
Sackler School of Graduate Biomedical Sciences, and the Department of Pathology, Tufts University School of Medicine, Boston, MA 02111, USA.
Brodeur
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PH
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005260:Female; D015321:Gene Rearrangement; D007135:Immunoglobulin Variable Region / Q000737:chemistry / Q000235:genetics*; D007145:Immunoglobulin kappa-Chains / Q000235:genetics*; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data
D007135:Immunoglobulin Variable Region; D007145:Immunoglobulin kappa-Chains