Tumor-infiltrating lymphocytes (TILs) are correlated to prognosis of several kinds of cancer. Most studies focused on T cells, while the role of tumor-associated B cells (TABs) has only recently gained more attention. TABs contain subpopulations with distinct functions, potentially promoting or inhibiting immune responses. This study provides a detailed analysis of TABs in gastro-esophageal adenocarcinoma (EAC). Flow cytometric analyses of single cell suspensions of tumor samples, mucosa, lymph nodes and peripheral blood mononuclear cells (PBMC) of EAC patients and healthy controls revealed a distinct B cell compartment in cancer patients. B cells were increased in tumor samples and subset-analyses of TILs showed increased proportions of differentiated and activated B cells and an enrichment for follicular T helper cells. Confocal microscopy demonstrated that TABs were mainly organized in tertiary lymphoid structures (TLS), which resemble lymphoid follicles in secondary lymphoid organs. A panel of 34 tumor-associated antigens (TAAs) expressed in EAC was identified based on public databases and TCGA data to analyze tumor-specific B cell responses using a LUMINEXTM bead assay and flow cytometry. Structural analyses of TLS and the detection of tumor-specific antibodies against one or more TAAs in 48.1% of analyzed serum samples underline presence of anti-tumor B cell responses in EAC. Interestingly, B cells were decreased in tumors with expression of Programmed Death Ligand 1 or impaired HLA-I expression. These data demonstrate that anti-tumor B cell responses are an additional and underestimated aspect of EAC. Our results are of immediate translational relevance to emerging immunotherapies.

中文翻译：

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食管胃腺癌中的 B 细胞高度分化，组织成三级淋巴结构并产生肿瘤特异性抗体。

肿瘤浸润淋巴细胞（TIL）与多种癌症的预后相关。大多数研究都集中在 T 细胞上，而肿瘤相关 B 细胞 (TAB) 的作用最近才得到更多关注。TAB 包含具有不同功能的亚群，可能促进或抑制免疫反应。本研究对胃食管腺癌 (EAC) 中的 TAB 进行了详细分析。对 EAC 患者和健康对照的肿瘤样本、粘膜、淋巴结和外周血单核细胞 (PBMC) 的单细胞悬浮液进行流式细胞术分析，揭示了癌症患者中独特的 B 细胞区室。肿瘤样本中的 B 细胞增加，TIL 的子集分析显示分化和活化的 B 细胞比例增加，滤泡 T 辅助细胞富集。共聚焦显微镜表明，TAB 主要组织在三级淋巴结构（TLS）中，类似于二级淋巴器官中的淋巴滤泡。根据公共数据库和 TCGA 数据，鉴定了 EAC 中表达的 34 种肿瘤相关抗原 (TAA)，以使用 LUMINEXTM 珠测定和流式细胞术分析肿瘤特异性 B 细胞反应。TLS 的结构分析以及在 48.1% 的分析血清样本中检测到针对一种或多种 TAA 的肿瘤特异性抗体强调了 EAC 中存在抗肿瘤 B 细胞反应。有趣的是，在表达程序性死亡配体1或HLA-I表达受损的肿瘤中，B细胞减少。这些数据表明，抗肿瘤 B 细胞反应是 EAC 的另一个被低估的方面。我们的结果与新兴免疫疗法具有直接的转化相关性。