Developmental pathways for B cell lymphogenesis are sufficiently known only in mice and humans. However, both of these species rearrange immunoglobulin heavy chains (IgH) before light chains (IgL) while IgL precedes IgH rearrangement in swine. We demonstrate here that this reversed order of rearrangements have some concealed consequences: (1) we confirmed that although IgLκ rearrangement is initial, most IgLλ⁺ B cells are generated earlier and before IgH rearrangements, while most IgLκ⁺ B cells later and after IgH rearrangements, (2) the second IgLκ rearrangement can occur after IgLλ rearrangement, (3) early formed B cells bear only single in-frame IgH rearrangements, (4) many IgLκ⁺ B cells carry IgLλ rearrangements that can be productive and occurring on both alleles in one cell, and (5) although VpreB and λ5 genes are present in swine, they are preferentially expressed in non-B cells. In summary, our findings reveal that swine use an alternative B cell developmental pathway as compared to mice and humans.

只有在小鼠和人类中才充分了解 B 细胞淋巴生成的发育途径。然而，这两种物种都在轻链 (IgL) 之前重排免疫球蛋白重链 (IgH)，而在猪中 IgL 先于 IgH 重排。我们在此证明这种颠倒的重排顺序有一些隐藏的后果：（1）我们证实，虽然 IgLκ 重排是初始的，但大多数 IgLλ ⁺ B 细胞在 IgH 重排之前和之前产生，而大多数 IgLκ ⁺ B 细胞在 IgH 重排之后和之后, (2) 第二次 IgLκ 重排可以发生在 IgLλ 重排之后，(3) 早期形成的 B 细胞仅具有单个框内 IgH 重排，(4) 许多 IgLκ ⁺B 细胞携带 IgLλ 重排，这些重排可以在一个细胞的两个等位基因上产生并发生，并且 (5) 尽管 VpreB 和 λ5 基因存在于猪中，但它们优先在非 B 细胞中表达。总之，我们的研究结果表明，与小鼠和人类相比，猪使用了另一种 B 细胞发育途径。