Background B cell receptor Immunoglobulin (BcR IG) repertoire of Chronic Lymphocytic Leukemia (CLL) is characterized by the expression of quasi-identical BcR IG. These are observed in approximately 30% of patients, defined as stereotyped receptors and subdivided into subsets based on specific VH CDR3 aa motifs and phylogenetically related IGHV genes. Although relevant to CLL ontogeny, the distribution of CLL-biased stereotyped immunoglobulin rearrangements (CBS-IG) in normal B cells has not been so far specifically addressed using modern sequencing technologies. Here, we have investigated the presence of CBS-IG in splenic B cell subpopulations (s-BCS) and in CD5 + and CD5 − B cells from the spleen and peripheral blood (PB). Methods Fractionation of splenic B cells into 9 different B cell subsets and that of spleen and PB into CD5 + and CD5 − cells were carried out by FACS sorting. cDNA sequences of BcR IG gene rearrangements were obtained by NGS. Identification of amino acidic motifs typical of CLL stereotyped subsets was carried out on IGHV1-carrying gene sequences and statistical evaluation has been subsequently performed to assess stereotypes distribution. Results CBS-IG represented the 0.26% average of IGHV1 genes expressing sequences, were detected in all of the BCS investigated. CBS-IG were more abundant in splenic and circulating CD5 + B (0.57%) cells compared to CD5 − B cells (0.17%). In all instances, most CBS IG did not exhibit somatic hypermutation similar to CLL stereotyped receptors. However, compared to CLL, they exhibited a different CLL subset distribution and a broader utilization of the genes of the IGHV1 family. Conclusions CBS-IG receptors appear to represent a part of the “public” BcR repertoire in normal B cells. This repertoire is observed in all BCS excluding the hypothesis that CLL stereotyped BcR accumulate in a specific B cell subset, potentially capable of originating a leukemic clone. The different relative representation of CBS-IG in normal B cell subgroups suggests the requirement for additional selective processes before a full transformation into CLL is achieved.

中文翻译：

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使用高通量免疫遗传学方法追踪正常 B 细胞亚群中 CLL 偏向的定型免疫球蛋白基因重排

背景 慢性淋巴细胞白血病 (CLL) 的 B 细胞受体免疫球蛋白 (BcR IG) 库的特征在于准相同 BcR IG 的表达。这些在大约 30% 的患者中观察到，定义为刻板的受体，并根据特定的 VH CDR3 aa 基序和系统发育相关的 IGHV 基因细分为子集。尽管与 CLL 个体发育相关，但迄今为止，尚未使用现代测序技术专门解决正常 B 细胞中偏向 CLL 的定型免疫球蛋白重排 (CBS-IG) 的分布。在这里，我们研究了 CBS-IG 在脾脏 B 细胞亚群 (s-BCS) 以及来自脾脏和外周血 (PB) 的 CD5 + 和 CD5 - B 细胞中的存在。方法通过FACS分选将脾B细胞分级为9个不同的B细胞亚群，将脾和PB分级为CD5 + 和CD5 - 细胞。通过NGS获得BcR IG基因重排的cDNA序列。对携带 IGHV1 的基因序列进行了 CLL 定型子集典型的氨基酸基序的鉴定，随后进行了统计评估以评估定型分布。结果 CBS-IG 代表 0.26% 平均 IGHV1 基因表达序列，在所有研究的 BCS 中检测到。与 CD5 - B 细胞 (0.17%) 相比，CBS-IG 在脾脏和循环 CD5 + B (0.57%) 细胞中更丰富。在所有情况下，大多数 CBS IG 没有表现出类似于 CLL 定型受体的体细胞超突变。然而，与 CLL 相比，他们表现出不同的 CLL 子集分布和对 IGHV1 家族基因的更广泛利用。结论 CBS-IG 受体似乎代表了正常 B 细胞中“公共”BcR 库的一部分。除了 CLL 定型 BcR 在特定 B 细胞亚群中积累的假设外，所有 BCS 中都观察到了该库，可能能够产生白血病克隆。CBS-IG 在正常 B 细胞亚群中的不同相对表示表明在完全转化为 CLL 之前需要额外的选择性过程。除了 CLL 定型 BcR 在特定 B 细胞亚群中积累的假设外，所有 BCS 中都观察到了该库，可能能够产生白血病克隆。CBS-IG 在正常 B 细胞亚群中的不同相对表示表明在完全转化为 CLL 之前需要额外的选择性过程。除了 CLL 定型 BcR 在特定 B 细胞亚群中积累的假设外，所有 BCS 中都观察到了该库，可能能够产生白血病克隆。CBS-IG 在正常 B 细胞亚群中的不同相对表示表明在完全转化为 CLL 之前需要额外的选择性过程。