N-linked glycans on immunoglobulin G (IgG) have been associated with pathogenesis of diseases and the therapeutic functions of antibody-based drugs; however, low-abundance species are difficult to detect. Here we show a glycomic approach to detect these species on human IgGs using a specialized microfluidic chip. We discover 20 sulfated and 4 acetylated N-glycans on IgGs. Using multiple reaction monitoring method, we precisely quantify these previously undetected low-abundance, trace and even ultra-trace N-glycans. From 277 patients with rheumatoid arthritis (RA) and 141 healthy individuals, we also identify N-glycan biomarkers for the classification of both rheumatoid factor (RF)-positive and negative RA patients, as well as anti-citrullinated protein antibodies (ACPA)-positive and negative RA patients. This approach may identify N-glycosylation-associated biomarkers for other autoimmune and infectious diseases and lead to the exploration of promising glycoforms for antibody therapeutics.Post-translational modifications can affect antibody function in health and disease, but identification of all variants is difficult using existing technologies. Here the authors develop a microfluidic method to identify and quantify low-abundance IgG N-glycans and show some of these IgGs can be used as biomarkers for rheumatoid arthritis.

中文翻译：

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一种鉴定痕量硫酸化IgG N-聚糖作为类风湿关节炎生物标志物的方法。

免疫球蛋白G（IgG）上的N-连接聚糖与疾病的发病机制和基于抗体的药物的治疗功能有关；然而，低丰度的物种很难被发现。在这里，我们展示了使用专门的微流控芯片在人IgG上检测这些物种的糖化方法。我们发现IgG上有20个硫酸化的和4个乙酰化的N-聚糖。使用多种反应监测方法，我们可以精确定量这些先前未检测到的低丰度，痕量甚至超痕量的N-聚糖。从277名类风湿性关节炎（RA）患者和141名健康个体中，我们还确定了N-聚糖生物标记物，用于对类风湿因子（RF）阳性和阴性RA患者以及抗瓜氨酸化蛋白抗体（ACPA）进行分类-阳性和阴性RA患者。这种方法可能会鉴定出与其他自身免疫和感染性疾病相关的N-糖基化相关生物标志物，并导致探索有前景的糖形式用于抗体治疗。翻译后修饰可影响抗体在健康和疾病中的功能，但使用现有的方法很难鉴定所有变体技术。在这里，作者开发了一种微流体方法来鉴定和定量低丰度IgG N-聚糖，并显示其中一些IgG可以用作类风湿关节炎的生物标记。