Center for Immunobiology and Department of Investigative Medicine, Western Michigan University Homer Stryker M.D. School of Medicine, Kalamazoo, MI, United States.
Front Immunol. 2023 Dec 15;14:1259827. doi: 10.3389/fimmu.2023.1259827. eCollection 2023.
Human B1 cells produce natural antibodies characterized by overutilization of heavy chain variable region VH4-34 in comparison to other B cell populations. VH4-34-containing antibodies have been reported to be autoreactive and to be associated with lupus and other autoimmune dyscrasias. However, it has been unclear to what extent VH4-34 antibodies manifest autoreactivity in B1 cells or other B cell populations-in other words, are VH4-34 containing antibodies autoreactive wherever found, or mainly within the B1 cell population? To address this issue we sort purified single human B1 and memory B cells and then amplified, sequenced, cloned and expressed VH4-34-containing antibodies from 76 individual B cells. Each of these antibodies was tested for autoreactivity by HEp-2 IFA and autoantigen ELISA. Antibodies were scored as autoreactive if positive by either assay. We found VH4-34 antibodies rescued from B1 cells were much more frequently autoreactive (14/48) than VH4-34 antibodies rescued from memory B cells (2/28). Among B1 cell antibodies, 4 were HEp-2+, 6 were dsDNA+ and 4 were positive for both. Considering only HEp-2+ antibodies, again these were found more frequently among B1 cell VH4-34 antibodies (8/48) than memory B cell VH4-34 antibodies (1/28). We found autoreactivity was associated with greater CDR3 length, as expected; however, we found no association between autoreactivity and a previously described FR1 "hydrophobic patch". Our results indicate that autoreactive VH4-34-containing antibodies tend to reside within the human B1 cell population.
人类 B1 细胞产生的天然抗体的重链可变区 VH4-34 过度利用，与其他 B 细胞群体相比。含有 VH4-34 的抗体已被报道为自身反应性的，并与狼疮和其他自身免疫功能紊乱有关。然而，目前还不清楚 VH4-34 抗体在 B1 细胞或其他 B 细胞群体中表现出自身反应性的程度——换句话说，无论在何处发现 VH4-34 抗体，它们是否具有自身反应性，还是主要存在于 B1 细胞群体中？为了解决这个问题，我们对纯化的单个人类 B1 和记忆 B 细胞进行分选，然后从 76 个单个 B 细胞中扩增、测序、克隆和表达含有 VH4-34 的抗体。通过 HEp-2 IFA 和自身抗原 ELISA 测试每种抗体的自身反应性。如果两种测定均为阳性，则将抗体评为自身反应性。我们发现从 B1 细胞中回收的 VH4-34 抗体比从记忆 B 细胞中回收的 VH4-34 抗体（2/28）更频繁地自身反应性（14/48）。在 B1 细胞抗体中，有 4 种是 HEp-2+，6 种是 dsDNA+，4 种是两者均阳性。仅考虑 HEp-2+抗体，再次发现 B1 细胞 VH4-34 抗体（8/48）比记忆 B 细胞 VH4-34 抗体（1/28）更频繁地出现。我们发现自身反应性与更长的 CDR3 长度有关，这是预期的；然而，我们没有发现自身反应性与先前描述的 FR1“疏水性补丁”之间的关联。我们的结果表明，自身反应性 VH4-34 抗体倾向于存在于人类 B1 细胞群体中。
