Martin Victoria G, Wu Yu-Chang Bryan, Townsend Catherine L, Lu Grace H C, O'Hare Joselli Silva, Mozeika Alexander, Coolen Anthonius C C, Kipling David, Fraternali Franca, Dunn-Walters Deborah K
Division of Infection, Immunity and Inflammatory Disease, Faculty of Life Sciences & Medicine, King's College London , London , UK.
Randall Division of Cell and Molecular Biophysics, Faculty of Life Sciences & Medicine, King's College London , London , UK.
Front Immunol. 2016 Dec 2;7:546. doi: 10.3389/fimmu.2016.00546. eCollection 2016.
The B cell repertoire is generated in the adult bone marrow by an ordered series of gene rearrangement processes that result in massive diversity of immunoglobulin (Ig) genes and consequently an equally large number of potential specificities for antigen. As the process is essentially random, the cells exhibiting excess reactivity with self-antigens are generated and need to be removed from the repertoire before the cells are fully mature. Some of the cells are deleted, and some will undergo receptor editing to see if changing the light chain can rescue an autoreactive antibody. As a consequence, the binding properties of the B cell receptor are changed as development progresses through pre-B ≫ immature ≫ transitional ≫ naïve phenotypes. Using long-read, high-throughput, sequencing we have produced a unique set of sequences from these four cell types in human bone marrow and matched peripheral blood, and our results describe the effects of tolerance selection on the B cell repertoire at the Ig gene level. Most strong effects of selection are seen within the heavy chain repertoire and can be seen both in gene usage and in CDRH3 characteristics. Age-related changes are small, and only the size of the CDRH3 shows constant and significant change in these data. The paucity of significant changes in either kappa or lambda light chain repertoires implies that either the heavy chain has more influence over autoreactivity than light chain and/or that switching between kappa and lambda light chains, as opposed to switching within the light chain loci, may effect a more successful autoreactive rescue by receptor editing. Our results show that the transitional cell population contains cells other than those that are part of the pre-B ≫ immature ≫ transitional ≫ naïve development pathway, since the population often shows a repertoire that is outside the trajectory of gene loss/gain between pre-B and naïve stages.
B细胞库在成年骨髓中通过一系列有序的基因重排过程产生，这些过程导致免疫球蛋白（Ig）基因的大量多样性，从而产生同样大量的潜在抗原特异性。由于这个过程本质上是随机的，与自身抗原有过度反应性的细胞会产生，并且在细胞完全成熟之前需要从库中清除。一些细胞被删除，一些细胞会进行受体编辑，看改变轻链是否能挽救自身反应性抗体。因此，随着B细胞受体的结合特性随着发育从pre - B≫未成熟≫过渡≫初始表型而进展。利用长读长、高通量测序，我们从人类骨髓和匹配的外周血中的这四种细胞类型产生了一组独特的序列，我们的结果描述了耐受选择在Ig基因水平对B细胞库的影响。选择的大多数强烈影响见于重链库，并且在基因使用和互补决定区3（CDRH3）特征中都能看到。与年龄相关的变化很小，在这些数据中只有CDRH3的大小显示出持续且显著的变化。κ或λ轻链库中显著变化的缺乏意味着要么重链对自身反应性的影响比轻链更大，和/或κ和λ轻链之间的转换，与轻链基因座内的转换相反，可能通过受体编辑实现更成功的自身反应性挽救。我们的结果表明，过渡细胞群体包含不属于pre - B≫未成熟≫过渡≫初始发育途径的细胞，因为该群体通常显示出一个不在pre - B和初始阶段之间基因丢失/获得轨迹范围内的库。
