Fc gamma receptors promote antibody-induced LILRB4 internalization and immune regulation of monocytic AML.
Fc gamma receptors promote antibody-induced LILRB4 internalization and immune regulation of monocytic AML.
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DOI：
10.1093/abt/tbad025
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发表时间：
2024-01
影响因子：
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通讯作者：
An, Zhiqiang
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文献类型：
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作者：
Morse, Joshua W;Gui, Xun;Deng, Mi;Huang, Ryan;Ye, Xiaohua;Zhao, Peng;Fan, Xuejun;Xiong, Wei;Zhang, Chengcheng;Zhang, Ningyan;An, Zhiqiang
免疫检查点白细胞免疫球蛋白样受体B4（LILRB 4）特异性地存在于急性单核细胞白血病（单核细胞AML）的细胞表面，这是一种侵袭性和常见的AML亚型。我们已经开发了人源化单克隆IgG 1 LILRB 4阻断抗体（h128-3），其改善了免疫调节，但在单核细胞AML模型中将LILRB 4的细胞表面表达降低了40- 60%。有趣的是，这种效应的大部分被抗体Fc区（h128-3/N297 A）的突变所中和，这阻止了与Fc γ受体（Fcγ R）的相互作用。这表明h128-3的作用存在Fcγ R依赖性抗原调节，这是一种已知改变靶向B细胞恶性肿瘤的抗体功能的机制。我们在单核细胞AML细胞系中通过CRISPR-Cas9介导的Fcγ R基因敲除破坏Fc-Fc γ R相互作用，以研究Fcγ R依赖性抗原调节在h128-3调节LILRB 4中的作用。当FcγRI被抑制或从单核细胞AML细胞表面去除时，h128-3不能最佳地发挥其阻断功能，导致LILRB 4抑制性受体激活，并导致T细胞介导的体外细胞毒性降低15-25%。在不存在FcγRI的情况下，FcγRIIa的支架化允许h128-3维持LILRB 4阻断功能。在这里，我们首次定义了免疫受体阻断抗体在髓系恶性肿瘤中的功能的Fcγ R依赖性抗原调节机制。这项研究将有助于开发安全，精确靶向的抗体治疗骨髓恶性肿瘤，具有更大的效力和疗效。重要性声明：LILRB 4中和抗体h128-3介导的受体内化部分依赖于IgG 1-Fc与单核细胞AML上Fcγ R的相互作用。已知Fcγ R依赖性抗原调节会深刻影响抗体（如利妥昔单抗）在B细胞恶性肿瘤中的功能。在这里，我们首次在AML中对其进行了表征。
The immune checkpoint leukocyte immunoglobulin-like receptor B4 (LILRB4) is found specifically on the cell surface of acute monocytic leukemia (monocytic AML), an aggressive and common subtype of AML. We have developed a humanized monoclonal IgG1 LILRB4-blocking antibody (h128-3), which improved immune regulation but reduced cell surface expression of LILRB4 in monocytic AML models by 40–60%. Interestingly, most of this effect was neutralized by mutation of the Fc region of the antibody (h128-3/N297A), which prevents interaction with Fc gamma receptors (FcγRs). This suggested that there is FcγR-dependent antigenic modulation underlying h128-3’s effects, a mechanism known to alter the function of antibodies targeting B-cell malignancies. We disrupted the Fc-FcγR interaction pharmacologically and with stable CRISPR-Cas9-mediated genetic knockout of FcγRs in monocytic AML cell lines to investigate the role of FcγR-dependent antigenic modulation in the regulation of LILRB4 by h128-3. When FcγRI is inhibited or removed from the surface of monocytic AML cells, h128-3 cannot optimally perform its blocking function, resulting in activation of the LILRB4 inhibitory receptor and leading to a 15–25% decrease in T-cell-mediated cytotoxicity in vitro. In the absence of FcγRI, scaffolding by FcγRIIa allows h128-3 to maintain LILRB4-blocking function. Here we define a FcγR-dependent antigenic modulation mechanism underlying the function of an immunoreceptor blocking antibody for the first time in myeloid malignancy. This research will facilitate the development of safe, precision-targeted antibody therapeutics in myeloid malignancies with greater potency and efficacy. Statement of Significance: Receptor internalization mediated by the LILRB4 neutralizing antibody h128-3 is in part dependent on the IgG1-Fc interaction with FcγRs on monocytic AML. FcγR-dependent antigenic modulation is known to profoundly affect the function of antibodies such as rituximab in B-cell malignancies. Here we characterize it for the first time in AML.