In addition to their role as antibody producing cells, B cells make a critical contribution to adaptive immune responses by functioning as professional antigen-presenting cells (APC). Distinctive features of B cells as APC include the expression of the B cell receptor (BCR) for antigen and regulated expression of HLA-DO. Here, we discuss recent progress in investigation of B cells as APC. We start with an update on the canonical MHC class II antigen presentation pathway in B cells and alternative pathways, including generation of extracellular vesicles. Turning to APC function, we highlight the roles of B cells as thymic APC, as APC for T follicular helper (TFH), as APC for CD4 memory T cells and as presenters of idiotypic BCR determinants. We also note recent examples that link B cell Ag-presentation to disease. Emerging evidence indicates that, in addition to unique features of B cells compared to other professional APC, there is appreciable heterogeneity among B cells, arising from, for example, B cell activation state or the microenvironment.

中文翻译：

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对 B 细胞作为抗原呈递细胞的新见解。

除了作为抗体产生细胞的作用外，B 细胞还通过作为专业抗原呈递细胞 (APC) 发挥作用，对适应性免疫反应做出了重要贡献。B 细胞作为 APC 的显着特征包括 B 细胞受体 (BCR) 的抗原表达和 HLA-DO 的调节表达。在这里，我们讨论了将 B 细胞作为 APC 研究的最新进展。我们首先更新了 B 细胞中典型的 MHC II 类抗原呈递途径和替代途径，包括细胞外囊泡的产生。谈到 APC 功能，我们强调了 B 细胞作为胸腺 APC、作为 T 滤泡辅助 (TFH) 的 APC、作为 CD4 记忆 T 细胞的 APC 和作为独特型 BCR 决定簇的呈递者的作用。我们还注意到最近将 B 细胞抗原呈递与疾病联系起来的例子。新出现的证据表明，