Feeney A J
Division of Immunology, Medical Biology Institute, La Jolla, CA 92037.
J Immunol. 1991 Dec 15;147(12):4343-50.
The primary antibody response to phosphorylcholine (PC) is dominated by T15 antibodies. There are three families of anti-PC antibodies which can be made in mice: T15, 511, and 603. All use the same H chain V, D, and J segments, but each anti-PC family has a different L chain, as well as a family-specific Vh-D junctional sequence. Here we test the hypothesis that T15 antibodies are dominant because the prototypic T15 V-D junction is generated in pre-B cells more often than the alternative non-T15 V-D junctional sequences. Rearranged IgH genes from DNA derived from fetal or newborn liver pre-B cells and from adult bone marrow pre-B cells of BALB/c mice were amplified by polymerase chain reaction, cloned, and sequenced. DNA from adult splenic B cells was also amplified, for comparison. All V1-DFL16.1 and DFL16.1-Jh1 junctional sequences were analyzed. Fifty-three percent (9/17) of all neonatal pre-B cell V-D junctions with V1 and DFL16.1 had the prototypic T15 junctional sequence, which has no N regions. In contrast, no prototypic T15 V-D junctions were observed in adult pre-B cells, and each junctional sequence was unique. Adult splenic B cells contained an intermediate number of T15-type V-D junctional sequences (7/21). The prototypic D-J junctional sequence used in many anti-PC antibodies was also observed in a high percentage of sequences. The high frequency of T15 junctions in the neonatal pre-B cells can be explained by two observations: 1) N regions are absent in neonatal but not adult junctions and 2) in the absence of N regions, joining of V, D, and J segments may be targeted to short regions of sequence homology near the ends of the genes. This mechanism would preferentially give rise to the T15 V-D and D-J junctions. Preservation of the T15 V-D junction in adult splenic B cells is most likely due to antigenic stimulation of long lived precursors, because a high frequency of T15-type D-J junctions are coexpressed with T15 V-D junctions in splenic sequences. These results predict that T15 anti-PC precursors would be made at a very high frequency in the neonate, and at a much lower frequency in the adult. This may explain why the neonatal period is critical in establishing T15 dominance.
对磷酸胆碱（PC）的初次抗体反应主要由T15抗体主导。在小鼠中可产生三类抗PC抗体：T15、511和603。它们都使用相同的重链V、D和J基因片段，但每个抗PC家族都有不同的轻链，以及家族特异性的Vh-D连接序列。在此，我们检验这样一个假说：T15抗体占主导地位是因为原型T15 V-D连接在pre-B细胞中产生的频率高于其他非T15 V-D连接序列。通过聚合酶链反应扩增、克隆并测序来自BALB/c小鼠胎儿或新生鼠肝脏pre-B细胞以及成年骨髓pre-B细胞DNA中的重排IgH基因。同时也扩增成年脾B细胞的DNA用于比较。分析所有V1-DFL16.1和DFL16.1-Jh1连接序列。所有带有V1和DFL16.1的新生pre-B细胞V-D连接中，53%（9/17）具有无N区的原型T15连接序列。相比之下，在成年pre-B细胞中未观察到原型T15 V-D连接，且每个连接序列都是独特的。成年脾B细胞含有中等数量的T15型V-D连接序列（7/21）。许多抗PC抗体中使用的原型D-J连接序列在高比例的序列中也被观察到。新生pre-B细胞中T15连接的高频率可由两点观察结果解释：1）新生连接中无N区，而成人连接中有；2）在无N区的情况下，V、D和J基因片段的连接可能靶向基因末端附近的短序列同源区域。这种机制将优先产生T15 V-D和D-J连接。成年脾B细胞中T15 V-D连接的保留很可能是由于长寿前体细胞的抗原刺激，因为在脾细胞序列中高频率的T15型D-J连接与T15 V-D连接共表达。这些结果预测，T15抗PC前体在新生儿中的产生频率会非常高，而在成年人中则低得多。这可能解释了为什么新生儿期对于确立T15的主导地位至关重要。
