Experimental Hematology Unit, Division of Immunology, Transplantation and Infectious Diseases, Ospedale San Raffaele Scientific Institute, Milano, Italy; Cell Therapy Immunomonitoring Laboratory (MITiCi), Division of Immunology, Transplantation and Infectious Diseases, Ospedale San Raffaele Scientific Institute.
Unit of Hematology and Bone Marrow Transplantation, Ospedale San Raffaele Scientific Institute.
Haematologica. 2023 Jun 1;108(6):1530-1543. doi: 10.3324/haematol.2022.280685.
After allogeneic hematopoietic stem cell transplantation (HSCT), the emergence of circulating cytomegalovirus (CMV)- specific T cells correlates with protection from CMV reactivation, an important risk factor for non-relapse mortality. However, functional assays measuring CMV-specific cells are time-consuming and often inaccurate at early time-points. We report the results of a prospective single-center, non-interventional study that identified the enumeration of Dextramerpositive CMV-specific lymphocytes as a reliable and early predictor of viral reactivation. We longitudinally monitored 75 consecutive patients for 1 year after allogeneic HSCT (n=630 samples). The presence of ≥0.5 CMV-specific CD8+ cells/mL at day +45 was an independent protective factor from subsequent clinically relevant reactivation in univariate (P<0.01) and multivariate (P<0.05) analyses. Dextramer quantification correlated with functional assays measuring interferon-γ production, and allowed earlier identification of high-risk patients. In mismatched transplants, the comparative analysis of lymphocytes restricted by shared, donor- and host-specific HLA revealed the dominant role of thymic-independent CMV-specific reconstitution. Shared and donor-restricted CMV-specific T cells reconstituted with similar kinetics in recipients of CMV-seropositive donors, while donor-restricted T-cell reconstitution from CMV-seronegative grafts was impaired, indicating that in primary immunological responses the emergence of viral-specific T cells is largely sustained by antigen encounter on host infected cells rather than by cross-priming/presentation by non-infected donor-derived antigen-presenting cells. Multiparametric flow cytometry and high-dimensional analysis showed that shared-restricted CMV-specific lymphocytes display a more differentiated phenotype and increased persistence than donor-restricted counterparts. In this study, monitoring CMV-specific cells by Dextramer assay after allogeneic HSCT shed light on mechanisms of immune reconstitution and enabled risk stratification of patients, which could improve the clinical management of post-transplant CMV reactivations.
异基因造血干细胞移植（HSCT）后，循环细胞巨化病毒（CMV）特异性 T 细胞的出现与 CMV 再激活的保护相关，CMV 再激活是导致非复发死亡率的重要危险因素。然而，测量 CMV 特异性细胞的功能测定耗时且在早期往往不准确。我们报告了一项前瞻性、单中心、非干预性研究的结果，该研究确定了 Dextramer 阳性 CMV 特异性淋巴细胞的计数是病毒再激活的可靠和早期预测指标。我们对 75 例连续患者进行了 1 年的异基因 HSCT 后监测（n=630 个样本）。在第+45 天，CMV 特异性 CD8+细胞/mL 水平≥0.5 是单变量（P<0.01）和多变量（P<0.05）分析中随后发生临床相关再激活的独立保护因素。Dextramer 定量与测量干扰素-γ产生的功能测定相关，并且可以更早地识别高危患者。在错配移植中，对受者中共享、供者和宿主特异性 HLA 限制的淋巴细胞进行比较分析，揭示了非胸腺依赖性 CMV 特异性重建的主导作用。在 CMV 血清阳性供者的受者中，共享和供者限制的 CMV 特异性 T 细胞以相似的动力学重建，而来自 CMV 血清阴性移植物的供者限制 T 细胞重建受损，表明在原发性免疫反应中，病毒特异性 T 细胞的出现主要是通过宿主感染细胞上的抗原接触维持，而不是由未感染的供体来源的抗原呈递细胞交叉引发/呈递。多参数流式细胞术和高维分析表明，共享限制的 CMV 特异性淋巴细胞比供者限制的 CMV 特异性淋巴细胞具有更分化的表型和更高的持久性。在这项研究中，异基因 HSCT 后通过 Dextramer 测定监测 CMV 特异性细胞阐明了免疫重建的机制，并对患者进行了风险分层，这可以改善移植后 CMV 再激活的临床管理。
