Bovin Nicolai, Obukhova Polina, Shilova Nadezhda, Rapoport Evgenia, Popova Inna, Navakouski Maksim, Unverzagt Carlo, Vuskovic Marko, Huflejt Margaret
Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russian Federation.
Biochim Biophys Acta. 2012 Sep;1820(9):1373-82. doi: 10.1016/j.bbagen.2012.02.005. Epub 2012 Feb 21.
Profiling of donor's antibodies using glycan arrays demonstrated presence of antibodies capable of binding to >100 mammalian glycans or their fragments. For example, relatively high binding to Galα1-4Galβ1-4GlcNAc (P(1)), Galα1-4Galβ1-4Glc (P(k)), Galβ1-3GlcNAc (Le(c)), 4-O-SuGalβ1-4GlcNAc, and GalNAcα1-3GalNAc (Fs) was found in all tested individuals. Affinity isolation using hapten-specific chromatography in combination with epitope mapping revealed their glycotopes. Notably, a significant part of the antibodies was capable of recognizing a fragment of larger glycans, for example, -Galβ1-4Glc of glycolipids, or Fucα1-3GlcNAc motif of Le(X)/Le(Y) antigens. Their epitope specificity did not vary between different healthy individuals. Nominally, all the mentioned immunoglobulins could be classified as auto-antibodies.
In this work we re-evaluated results published earlier and analyzed new data to address the question why autologous antibodies found in healthy individuals do not cause severe auto-immune reactions.
In all cases the presumably "auto" antibodies were found to bind short fragments "subtracted" from larger glycans whereas recognition of the same fragment in the context of the whole natural chain was completely abolished. Thus, in spite of numerous formally positive signals observed on the printed glycan array, we are yet unable to identify in blood serum of healthy individuals true auto-antibodies capable of binding carbohydrate chains in their naturally occurring form.
The identified natural anti-glycan antibodies were found to be specific, high-titer and population conservative immunoglobulins - all of this suggesting as yet unknown biological role(s) of the studied proteins. This article is part of a Special Issue entitled Glycoproteomics.
利用聚糖阵列对供体抗体进行分析表明，存在能够与100多种哺乳动物聚糖或其片段结合的抗体。例如，在所有测试个体中均发现其与Galα1-4Galβ1-4GlcNAc（P(1)）、Galα1-4Galβ1-4Glc（P(k)）、Galβ1-3GlcNAc（Le(c)）、4-O-硫酸化Galβ1-4GlcNAc以及GalNAcα1-3GalNAc（Fs）具有较高的结合力。使用半抗原特异性色谱法结合表位作图进行亲和分离，揭示了它们的糖基表位。值得注意的是，相当一部分抗体能够识别较大聚糖的片段，例如糖脂的-Galβ1-4Glc，或Le(X)/Le(Y)抗原的Fucα1-3GlcNAc基序。它们的表位特异性在不同健康个体之间并无差异。理论上，所有上述免疫球蛋白均可归类为自身抗体。
在本研究中，我们重新评估了先前发表的结果，并分析了新数据，以解决为何在健康个体中发现的自身抗体会不引发严重自身免疫反应这一问题。
在所有情况下，推测的“自身”抗体均被发现可结合从较大聚糖“减去”的短片段，而在完整天然链的背景下对同一片段的识别则完全消失。因此，尽管在打印的聚糖阵列上观察到大量形式上的阳性信号，但我们仍无法在健康个体的血清中鉴定出能够以天然存在形式结合碳水化合物链的真正自身抗体。
已鉴定出的天然抗聚糖抗体是特异性、高滴度且群体保守的免疫球蛋白——所有这些都表明所研究蛋白质具有尚未明确的生物学作用。本文是名为“糖蛋白质组学”的特刊的一部分。
