Autoimmune diseases are frequently associated with autoantibodies. Recently, large sets of autoantibody-targeted antigens ("autoantigen-omes") of patient and control sera have been revealed, enabling autoantigen-omic approaches. However, statistical standards for defining such autoantigen-omes are lacking. The z-score indicates how many standard deviations an antigen reactivity of a given sample is from the mean reactivity of the corresponding antigen in a reference group. Hence, it is a common measure to define significantly positive reactivity in autoantigen profiling approaches. Here, we address the risk of biased analyses resulting from unbalanced selection of the reference group. Three study groups were selected. Patients-of-interest were chronic inflammatory demyelinating polyneuropathy (CIDP); controls were other neuropathies (ONP); and healthy controls (HC). Each serum was screened for significant autoantigen reactivity using HuProt™ protein arrays. We compared three possible selections of reference groups for statistical z-score calculations: method#1, the control groups (ONP + HC); method #2, all groups together; method #3, the respective other groups (e.g., CIDP + HC for the ONP autoantigen-ome). The method selection seriously affected the size of the autoantigen-omes. Method #1 introduced a bias favoring significantly more antigens per patient in the CIDP group (for z >4: 19 ± 3 antigens) than in the control groups (ONP: 2 ± 1; HC: 0 ± 0). The more balanced methods #2 and #3 did not result in significant differences. This contribution may help to avoid interpretation biases and to develop guidelines for population studies revealing autoantigen-omes via high throughput studies such as protein microarrays, immunoprecipitation with mass spectrometry, or phage display assays.

中文翻译：

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自身抗体靶向抗原组的正确定义依赖于适当的参考组选择

自身免疫性疾病通常与自身抗体有关。最近，已经揭示了患者和对照血清的大量自身抗体靶向抗原（“自身抗原组”），从而实现了自身抗原组学方法。然而，缺乏定义此类自身抗原组的统计标准。z 分数表示给定样品的抗原反应性与参考组中相应抗原的平均反应性相差多少标准差。因此，在自身抗原分析方法中定义显着阳性反应性是一种常用措施。在这里，我们解决了由于参考组的选择不平衡而导致的偏倚分析的风险。选择了三个研究组。感兴趣的患者是慢性炎症性脱髓鞘性多发性神经病 (CIDP)；对照是其他神经病（ONP）；和健康对照 (HC)。使用 HuProt™ 蛋白质阵列筛选每种血清的显着自身抗原反应性。我们比较了三种可能的参考组选择以进行统计 z 分数计算：方法#1，对照组（ONP + HC）；方法#2，所有组在一起；方法#3，相应的其他组（例如，用于ONP 自身抗原组的CIDP + HC）。方法选择严重影响自身抗原组的大小。方法 #1 引入了偏向于在 CIDP 组（对于 z > 4：19 ± 3 抗原）中比对照组（ONP：2 ± 1；HC：0 ± 0）中的每个患者明显更多的抗原。更平衡的方法#2 和#3 没有导致显着差异。