Ectopic lymphoid follicles (ELFs), resembling germinal centre-like structures, emerge in a variety of infectious and autoimmune and neoplastic diseases. ELFs can be found in the meninges of around 40% of the investigated progressive multiple sclerosis (MS) post-mortem brain tissues and are associated with the severity of cortical degeneration and clinical disease progression. Of predominant importance for progressive neuronal damage during the progressive MS phase appears to be meningeal inflammation, comprising diffuse meningeal infiltrates, B-cell aggregates and compartmentalized ELFs. However, the absence of a uniform definition of ELFs impedes reproducible and comparable neuropathological research in this field. In this review article, we will first highlight historical aspects and milestones around the discovery of ELFs in the meninges of progressive MS patients. In the next step, we discuss how animal models may contribute to an understanding of the mechanisms underlying ELF formation. Finally, we summarize challenges in investigating ELFs and propose potential directions for future research.

中文翻译：

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进行性多发性硬化症中的异位淋巴滤泡：从患者到动物模型

异位淋巴滤泡 (ELF) 类似于生发中心样结构，出现在各种感染性、自身免疫性和肿瘤性疾病中。ELF 可以在大约 40% 的进行性多发性硬化症 (MS)死后的脑膜中找到脑组织，并与皮质退化的严重程度和临床疾病进展有关。在进行性 MS 阶段，对进行性神经元损伤最重要的似乎是脑膜炎症，包括弥漫性脑膜浸润、B 细胞聚集体和分隔的 ELF。然而，缺乏对 ELF 的统一定义阻碍了该领域可重复和可比较的神经病理学研究。在这篇评论文章中，我们将首先强调在进展性 MS 患者脑膜中发现 ELF 的历史方面和里程碑。在下一步中，我们将讨论动物模型如何有助于理解 ELF 形成的潜在机制。最后，我们总结了调查 ELF 的挑战，并提出了未来研究的潜在方向。