Department of Patologi, Herlev og Gentofte Hospital, Herlev, Denmark.
Department of Hematology, Herlev og Gentofte Hospital, Herlev, Denmark.
Hematol Oncol. 2021 Aug;39(3):284-292. doi: 10.1002/hon.2839. Epub 2021 Feb 8.
We investigated the intratumoral source of PD-L1 expression and the infiltration of tumor-associated macrophages (TAMs) in large B-cell lymphomas (LBCLs) with or without MYC-translocation, as well as possible correlations to BCL2-and BCL6-translocations and cell of origin (COO). One-hundred and twenty-six patient samples were studied in a cohort enriched for MYC-translocated tumors with 34 samples carrying this translocation. Demonstration of intratumoral distribution and cellular source of PD-L1 was enabled by immunohistochemical (IHC) dual staining specifically highlighting PD-L1 expression in lymphoma B-cells with antibodies against PD-L1 and PAX5. Additional IHC with antibodies against CD68 and CD163 identified TAMs. We found that CD68-positive TAMs were the main source of PD-L1 protein expression in contrast to lymphoma B cells which rarely expressed PD-L1. Semiquantitative IHC demonstrated a significant correlation between CD68 and PD-L1 protein expression. Unsupervised hierarchical analysis of PD-L1, CD68, and CD163 IHC data subsequently demonstrated three potential clusters defined by expression of the three biomarkers. Cluster A consisted of patient samples with significantly lower expression of PD-L1, CD68, and CD163, but also significantly higher prevalence of BCL2-translocation and MYC-BCL2-double-hit (DH) compared to the other two clusters. In cluster C we found a significant accumulation of BCL6 translocated tumors. This cluster in contrast had the highest protein expression of PD-L1, CD68, and CD163. Cluster B tumors had an intermediate expression of the three biomarkers, but no accumulation of the specific genetic translocations. Our data, which were based on morphological analysis, immunophenotyping and genotyping by fluorescence in situ hybridization were in line with new concepts of LBCL taxonomy integrating genetic, phenotypical, and immunological characteristics with identification of new subgroups where MYC translocation and MYC-BCL2 DH may identify a noninflamed subtype. These findings may furthermore hold significant predictive value especially regarding immune checkpoint blockade therapy, but further molecular characterization should be done to substantiate this hypothesis.
我们研究了伴有或不伴有 MYC 易位的大 B 细胞淋巴瘤（LBCL）中 PD-L1 表达的肿瘤内来源和肿瘤相关巨噬细胞（TAMs）浸润，以及与 BCL2 和 BCL6 易位和细胞起源（COO）的可能相关性。在一个富含 MYC 易位肿瘤的队列中，对 126 例患者样本进行了研究，其中 34 例携带这种易位。通过免疫组织化学（IHC）双重染色特异性地突出抗 PD-L1 和 PAX5 抗体在淋巴瘤 B 细胞中的 PD-L1 表达，实现了肿瘤内分布和 PD-L1 细胞来源的证明。用针对 CD68 和 CD163 的 IHC 进一步鉴定 TAMs。我们发现 CD68 阳性 TAMs 是 PD-L1 蛋白表达的主要来源，而与淋巴瘤 B 细胞相反，后者很少表达 PD-L1。半定量 IHC 显示 CD68 和 PD-L1 蛋白表达之间存在显著相关性。随后对 PD-L1、CD68 和 CD163 IHC 数据进行无监督层次分析，根据这三个生物标志物的表达，显示出三个潜在的聚类。A 组由 PD-L1、CD68 和 CD163 表达显著降低的患者样本组成，但与另外两个聚类相比，BCL2 易位和 MYC-BCL2 双打击（DH）的发生率也显著升高。在 C 组中，我们发现 BCL6 易位肿瘤的显著聚集。与其他两个聚类相比，该聚类中 PD-L1、CD68 和 CD163 的蛋白表达最高。B 组肿瘤的三个标志物表达中等，但没有特定遗传易位的积累。我们的数据基于形态学分析、免疫表型和荧光原位杂交的基因分型，与整合遗传、表型和免疫学特征的新的 LBCL 分类学概念一致，并确定了新的亚组，其中 MYC 易位和 MYC-BCL2 DH 可能确定一种非炎症亚型。这些发现可能具有重要的预测价值，特别是关于免疫检查点阻断治疗，但需要进一步的分子特征描述来证实这一假设。
