Department of Experimental Therapy, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wroclaw, Poland.
Department and Clinic of Urology and Oncologic Urology, Wroclaw Medical University, Wroclaw, Poland.
J Immunol Res. 2020 Jul 28;2020:6545921. doi: 10.1155/2020/6545921. eCollection 2020.
Chronic lymphocytic leukemia (CLL) is characterized by the peripheral accumulation of neoplastic B cells and is frequently complicated by the systemic immunosuppression associated with an impairment in B and T lymphocyte activation. We hypothesized that the expression of immune checkpoint suppressors B and T lymphocyte attenuator (BTLA) and cytotoxic T lymphocyte antigen (CTLA-4) is disturbed in both lymphocyte subpopulations in CLL. The expression of CTLA-4 and BTLA mRNA was determined by real-time PCR, while CTLA-4 protein expression (surface or intracellular) was estimated in BTLA+ lymphocytes by flow cytometry. In CLL patients, we observed a higher gene transcript level of BTLA and CTLA-4 than in healthy individuals in both freshly isolated and PMA stimulated B and T cells. Remarkably, lower amounts of both inhibitory proteins were found in peripheral blood (PB) CLL B cells, whereas normal BTLA and elevated CTLA-4 were found in T cells. Consistently, there was a prevalence of CTLA-4+ cells within circulating BTLA+ T cells cells of patients confronting PB healthy cells. After stimulation, the only change found in CLL patients was a decrease in BTLA expression in B and T lymphocytes. In contrast, healthy lymphocytes responded more vigorously as regards the BTLA and CTLA expression with substantially higher frequency of CD69+ cells under the stimulating condition compared to corresponding cells from the CLL group. Our results indicate that CLL development is associated with the affected expression of BTLA and CTLA-4 checkpoint receptors in PB and its impaired expression might be associated with lowering of the threshold for B cell activation and proliferation, while upregulated CTLA-4 expression in CLL peripheral BTLA+ T cells may contribute to suppressed T cell effector functions. This hypothesis needs to be validated in future studies, which would allow us to explain how the increased or decreased expression of these molecules affects the cell function.
慢性淋巴细胞白血病（CLL）的特征是外周积累肿瘤性 B 细胞，并经常伴有与 B 和 T 淋巴细胞激活受损相关的全身免疫抑制。我们假设在 CLL 的淋巴细胞亚群中，免疫检查点抑制剂 B 和 T 淋巴细胞衰减因子（BTLA）和细胞毒性 T 淋巴细胞抗原（CTLA-4）的表达均受到干扰。通过实时 PCR 测定 CTLA-4 和 BTLA mRNA 的表达，通过流式细胞术在 BTLA+淋巴细胞中评估 CTLA-4 蛋白表达（表面或细胞内）。在 CLL 患者中，我们观察到与健康个体相比，在新鲜分离和 PMA 刺激的 B 和 T 细胞中，BTLA 和 CTLA-4 的基因转录水平均较高。值得注意的是，在外周血（PB）CLL B 细胞中发现这两种抑制蛋白的含量较低，而 T 细胞中则发现正常 BTLA 和升高的 CTLA-4。一致地，在患者的循环 BTLA+T 细胞中存在 CTLA-4+细胞。刺激后，在 CLL 患者中仅发现 B 和 T 淋巴细胞中的 BTLA 表达下降。相比之下，健康淋巴细胞对 BTLA 和 CTLA 表达的反应更为强烈，在刺激条件下，与来自 CLL 组的相应细胞相比，CD69+细胞的频率更高。我们的结果表明，CLL 的发展与 PB 中 BTLA 和 CTLA-4 检查点受体的表达异常有关，其表达受损可能与 B 细胞激活和增殖的阈值降低有关，而 CLL 外周 BTLA+T 细胞中上调的 CTLA-4 表达可能有助于抑制 T 细胞效应功能。这一假设需要在未来的研究中得到验证，这将使我们能够解释这些分子的表达增加或减少如何影响细胞功能。
