从原代人单核细胞中抗体结合 Fcγ 受体的特异性 N-糖基化分析。

Site-specific N-glycan Analysis of Antibody-binding Fc γ Receptors from Primary Human Monocytes.

机构信息

Roy J. Carver Department of Biochemistry, Biophysics & Molecular Biology, Iowa State University, Ames Iowa 50011.

Roy J. Carver Department of Biochemistry, Biophysics & Molecular Biology, Iowa State University, Ames Iowa 50011

出版信息

Mol Cell Proteomics. 2020 Feb;19(2):362-374. doi: 10.1074/mcp.RA119.001733. Epub 2019 Dec 30.

Abstract

FcγRIIIa (CD16a) and FcγRIIa (CD32a) on monocytes are essential for proper effector functions including antibody dependent cellular cytotoxicity (ADCC) and phagocytosis (ADCP). Indeed, therapeutic monoclonal antibodies (mAbs) that bind FcγRs with greater affinity exhibit greater efficacy. Furthermore, post-translational modification impacts antibody binding affinity, most notably the composition of the asparagine(N)-linked glycan at N162 of CD16a. CD16a is widely recognized as the key receptor for the monocyte response, however the post-translational modifications of CD16a from endogenous monocytes are not described. Here we isolated monocytes from individual donors and characterized the composition of CD16a and CD32a N-glycans from all modified sites. The composition of CD16a N-glycans varied by glycosylation site and donor. CD16a displayed primarily complex-type biantennary N-glycans at N162, however some individuals expressed CD16a V158 with ∼20% hybrid and oligomannose types which increased affinity for IgG1 Fc according to surface plasmon resonance binding analyses. The CD16a N45-glycans contain markedly less processing than other sites with >75% hybrid and oligomannose forms. N38 and N74 of CD16a both contain highly processed complex-type N-glycans with N-acetyllactosamine repeats and complex-type biantennary N-glycans dominate at N169. The composition of CD16a N-glycans isolated from monocytes included a higher proportion of oligomannose-type N-glycans at N45 and less sialylation plus greater branch fucosylation than we observed in a recent analysis of NK cell CD16a. The additional analysis of CD32a from monocytes revealed different features than observed for CD16a including the presence of a predominantly biantennary complex-type N-glycans with two sialic acids at both sites (N64 and N145).

摘要

FcγRIIIa(CD16a)和 FcγRIIa(CD32a)在单核细胞上对于适当的效应功能是必不可少的,包括抗体依赖性细胞毒性(ADCC)和吞噬作用(ADCP)。事实上,与 FcγR 结合亲和力更高的治疗性单克隆抗体(mAb)表现出更高的疗效。此外,翻译后修饰会影响抗体结合亲和力,最显著的是 CD16a 上 N162 的天冬酰胺(N)-连接聚糖的组成。CD16a 被广泛认为是单核细胞反应的关键受体,但是内源性单核细胞的 CD16a 的翻译后修饰尚未被描述。在这里,我们从个体供体中分离单核细胞,并从所有修饰位点表征 CD16a 和 CD32a N-聚糖的组成。CD16a N-聚糖的组成因糖基化位点和供体而异。CD16a 在 N162 上主要显示出复杂型双天线 N-聚糖,但一些个体表达的 CD16a V158 约有 20%的杂交和寡甘露糖类型,根据表面等离子体共振结合分析,这增加了对 IgG1 Fc 的亲和力。CD16a N45-聚糖的加工程度明显低于其他位点,超过 75%的形式为杂交和寡甘露糖。CD16a 的 N38 和 N74 都含有高度加工的复杂型 N-聚糖,具有 N-乙酰乳糖胺重复和复杂型双天线 N-聚糖在 N169 上占主导地位。从单核细胞中分离的 CD16a N-聚糖的组成包括 N45 处更高比例的寡甘露糖型 N-聚糖和比我们最近对 NK 细胞 CD16a 的分析中观察到的更少的唾液酸化和更大的分支岩藻糖基化。对单核细胞中 CD32a 的额外分析显示出与 CD16a 不同的特征,包括存在两个唾液酸的主要双天线复杂型 N-聚糖在两个位点(N64 和 N145)。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/f523/7000114/8ab2a7917e92/zjw0022060840007.jpg

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