V(H) CDR3-DEPENDENT POSITIVE SELECTION OF MURINE V(H)12-EXPRESSING B-CELLS IN THE NEONATE
V(H) CDR3-DEPENDENT POSITIVE SELECTION OF MURINE V(H)12-EXPRESSING B-CELLS IN THE NEONATE
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DOI：
10.1002/eji.1830231240
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发表时间：
1993-12-01
影响因子：
5.4
通讯作者：
MCCRAY, SK
中科院分区：
文献类型：
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作者：
CLARKE, SH;MCCRAY, SK
来自未操作小鼠的5%至15%的腹膜B 1（CD 5+）细胞产生结合菠萝蛋白酶处理的小鼠红细胞和半抗原磷脂酰胆碱（PtC）的抗体。这些B细胞中的大多数表达两种V（H）/Nkappa基因组合V（H）12/Vkappa 4或V（H）11/Vkappa 9中的任一种。V（H）11和V（H）12基因均重排为JH 1，并编码长度和序列受限的第三互补决定区（CDR 3）。这些和其他观察结果有力地证明了PtC特异性B1细胞是抗原选择的。为了确定在小鼠中何时开始选择PtC特异性B1细胞，我们使用聚合酶链反应扩增来自胎儿和新生小鼠肝脏的V（H）12-D-J（H）I重排，并确定单个克隆的CDR 3编码序列。我们发现在这两个发育阶段，生产性（P）与非生产性（NP）重排的比率异常低（0.4 - 1.0）。出生1天新生儿的P重排在D基因的使用以及其推导的V（H）CDR 3的序列和长度方面存在偏倚。这些偏差类似于成年人腹膜中的PtC特异性B1细胞。D基因的使用和CDR 3长度和序列在18天胎肝中早2至3天的V（H）12 P重排中的偏倚显著较小。我们认为，这种快速的变化是由于依赖于VHCDR 3序列的配体选择。我们进一步认为，大多数表达V（H）12的细胞不是配体选择的，因此经历了程序性细胞死亡。第1天新生儿肝脏中的限制性证据和胎儿中的低P/NP比表明，表达V（H）12的细胞的选择在出生前就开始了。
Five to fifteen percent of peritoneal B 1 (CD5+) cells from unmanipulated mice produce antibodies that bind bromelain-treated mouse red blood cells and the hapten phosphatidylcholine (PtC). The majority of these B cells express either of two V(H)/Nkappa gene combinations, V(H)12/Vkappa4 or V(H)11/Vkappa9. Both the V(H)11 and V(H)12 genes are rearranged to JH1 and encode third complementarity determining regions (CDR3) of restricted length and sequence. These and other observations argue strongly that PtC-specific B1 cells are antigen selected. To determine when selection of PtC-specific B1 cells begins in mice we have used the polymerase chain reaction to amplify V(H)12-D-J(H)I rearrangements from livers of fetal and neonatal mice, and determined the CDR3 encoding sequences of individual clones. We find an unusually low ratio of productive (P) to non-productive (NP) rearrangements (0.4 - 1.0) at both developmental stages. P rearrangements in day 1 neonates are biased in D gene use and in the sequence and length of their deduced V(H) CDR3. These biases are similar to those of PtC-specific B1 cells in the adult peritoneum. D gene use and CDR3 length and sequence are significantly less biased among V(H)12 P rearrangements 2 to 3 days earlier in the day 18 fetal liver. We suggest that this rapid change in repertoire is due to positive ligand selection that is dependent on the sequence of VH CDR3.We suggest further that the majority Of V(H)12-expressing cells are not ligand selected and consequently undergo programmed cell death. The evidence of restriction in day 1 neonatal livers and the low P/NP ratio in the fetus suggests that selection Of V(H)12-expressing cells begins before birth.