The level of immunoglobulin M (IgM) displayed on the surface of peripheral blood B cells exhibits a broad dynamic range and has been associated with both development and selection. To determine whether IgM surface expression associates with distinct immunoglobulin heavy-chain (IGH) repertoire properties, we performed deep IgM sequencing of peripheral blood transitional and mature naïve B cells in the upper and lower quartiles of surface IgM expression for 12 healthy donors. Mature naïve B cells within the lowest quartile for surface IgM expression displayed more diverse IGH features including increased complementarity-determining region 3 length, IGHJ6 segment usage and aromatic amino acids compared with mature naïve B cells with high surface IgM. There were no differences between IGH repertoires for transitional B cells with high or low surface IgM. These findings suggest that a selection checkpoint during progression of transitional to mature naïve B cells reduces the breadth of the IGH repertoire among high surface IgM B cells but that diversity is preserved in B cells expressing low levels of surface IgM.

中文翻译：

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人类过渡和 IgMlow 成熟的幼稚 B 细胞保留允许的 B 细胞受体

外周血 B 细胞表面显示的免疫球蛋白 M (IgM) 水平表现出广泛的动态范围，并与发育和选择相关。为了确定 IgM 表面表达是否与不同的免疫球蛋白重链 (IGH) 库特性相关，我们对 12 名健康供体的表面 IgM 表达的上下四分位数中的外周血过渡和成熟幼稚 B 细胞进行了深度 IgM 测序。与具有高表面 IgM 的成熟幼稚 B 细胞相比，表面 IgM 表达最低四分位数内的成熟幼稚 B 细胞显示出更多样的 IGH 特征，包括增加的互补决定区 3 长度、IGHJ6 片段使用和芳香族氨基酸。具有高或低表面 IgM 的过渡 B 细胞的 IGH 库之间没有差异。这些发现表明，在过渡到成熟幼稚 B 细胞过程中的选择检查点降低了高表面 IgM B 细胞中 IGH 库的广度，但在表达低水平表面 IgM 的 B 细胞中保留了多样性。