NIBRT Glycobiology Group, National Institute for Bioprocessing Research and Training, Foster's Avenue, Mount Merrion, Blackrock, County Dublin, Ireland.
J Proteome Res. 2013 Aug 2;12(8):3721-37. doi: 10.1021/pr400344h. Epub 2013 Jul 11.
Immune recognition of nonself is coordinated through complex mechanisms involving both innate and adaptive responses. Circulating antibodies communicate with effector cells of the innate immune system through surface receptors known as Fcγ receptors (FcγRs). The FcγRs are single-pass transmembrane glycoproteins responsible for regulating innate effector responses toward antigenic material. Although immunoglobulin G (IgG) antibodies bind to a range of receptors, including complement receptors and C-type lectins, we have focused on the Fcγ receptors. A total of five functional FcγRs are broadly classified into three families (FcγRI, FcγRII, and FcγRIII) and together aid in controlling both inflammatory and anti-inflammatory responses of the innate immune system. Due to the continued success of monoclonal antibodies in treating cancer and autoimmune disorders, research is typically directed toward improving the interaction of antibodies with the FcγRs through manipulation of IgG properties such as N-linked glycosylation. Biochemical studies using recombinant forms of the FcγRs are often used to quantitate changes in binding affinity, a key indicator of a likely biological outcome. However, analysis of the FcγRs themselves is imperative as recombinant FcγRs differ greatly from those observed in humans. In particular, the N-linked glycan composition is significantly important due to its function in the IgG-FcγR interaction. Here, we present data for the N-linked glycans present on FcγRs produced in NS0 cells, namely, FcγRIa, FcγRIIa, FcγRIIB, FcγRIIIa, and FcγRIIIb. Importantly, these FcγRs demonstrate typical murine glycosylation in the form of α-galactose epitopes, N-glycolylneuraminic acid, and other key glycan properties that are generally expressed in murine cell lines and therefore are not typically observed in humans.
免疫识别非自身是通过涉及先天和适应性反应的复杂机制协调的。循环抗体通过称为 Fcγ 受体 (FcγR) 的表面受体与先天免疫系统的效应细胞进行通信。FcγR 是单通道跨膜糖蛋白，负责调节针对抗原物质的先天效应反应。虽然免疫球蛋白 G (IgG) 抗体结合一系列受体，包括补体受体和 C 型凝集素，但我们专注于 Fcγ 受体。总共五种功能 FcγR 广泛分为三个家族（FcγRI、FcγRII 和 FcγRIII），共同有助于控制先天免疫系统的炎症和抗炎反应。由于单克隆抗体在治疗癌症和自身免疫性疾病方面的持续成功，研究通常旨在通过操纵 IgG 特性（如 N 连接糖基化）来改善抗体与 FcγR 的相互作用。使用 FcγR 的重组形式进行的生化研究通常用于定量结合亲和力的变化，这是生物结果的关键指标。然而，FcγR 本身的分析至关重要，因为重组 FcγR 与人类观察到的 FcγR 有很大的不同。特别是，N 连接聚糖组成非常重要，因为它在 IgG-FcγR 相互作用中起作用。在这里，我们展示了在 NS0 细胞中产生的 FcγR 上存在的 N 连接聚糖的数据，即 FcγRIa、FcγRIIa、FcγRIIB、FcγRIIIa 和 FcγRIIIb。重要的是，这些 FcγR 以α-半乳糖表位、N-羟乙酰神经氨酸和其他关键糖基化特性的形式表现出典型的鼠糖基化，这些特性通常在鼠细胞系中表达，因此通常在人类中观察不到。
