Molecular evidence for repertoire skewing of T large granular lymphocyte proliferation after allogeneic hematopoietic SCT: report of two cases

The Value of Flow Cytometry Clonality in Large Granular Lymphocyte Leukemia

Simple Summary

Large granular lymphocyte (LGL) leukemia, a lymphoproliferative disease, is characterized by an increased frequency of large-sized lymphocytes with typical expression of T-cell receptor (TCR) αβ, CD3, CD8, CD16, CD45RA, and CD57, and with the expansion of one to three subfamilies of the TCR variable β chain reflecting gene rearrangements. Molecular analysis remains the gold standard for confirmation of TCR clonality; however, flow cytometry is time and labor saving, and can be associated with simultaneous investigation of other surface markers. Moreover, Vβ usage by flow cytometry can be employed for monitoring clonal kinetics during treatment and follow-up of LGL leukemia patients.

Abstract

Large granular lymphocyte (LGL) leukemia is a lymphoproliferative disorder of mature T or NK cells frequently associated with autoimmune disorders and other hematological conditions, such as myelodysplastic syndromes. Immunophenotype of LGL cells is similar to that of effector memory CD8⁺ T cells with T-cell receptor (TCR) clonality defined by molecular and/or flow cytometric analysis. Vβ usage by flow cytometry can identify clonal TCR rearrangements at the protein level, and is fast, sensitive, and almost always available in every Hematology Center. Moreover, Vβ usage can be associated with immunophenotypic characterization of LGL clone in a multiparametric staining, and clonal kinetics can be easily monitored during treatment and follow-up. Finally, Vβ usage by flow cytometry might identify LGL clones silently underlying other hematological conditions, and routine characterization of Vβ skewing might identify recurrent TCR rearrangements that might trigger aberrant immune responses during hematological or autoimmune conditions.

[Clinical features and risk factors analyses of patients with T cell large granular lymphocytosis following allo-HSCT]

目的

探讨异基因造血干细胞移植（allo-HSCT）后发生T大颗粒淋巴细胞增多（T-LGL）患者的临床特征、相关因素以及对预后的影响。

方法

回顾性分析2013年6月至2020年2月接受allo-HSCT的359例患者连续性资料，男216例，女143例，中位年龄为38（7~65）岁。分析T-LGL的临床特征、累积发生率，比较发生与未发生T-LGL患者的总生存（OS）率、无病生存（DFS）率、累积复发率（CIR）及非复发死亡率（NRM）的差异，并研究影响移植后发生T-LGL的相关因素。

结果

共入组359例患者，T-LGL组17例，非LGL组342例，中位随访38（3~92）个月，移植后1、2、3年T-LGL累积发生率分别为3.64%（95%CI 1.09%~6.19%）、4.50%（95%CI 1.36%~7.64%）和4.84%（95%CI 1.10%~8.76%）；移植受者CMV再激活（P=0.013）、EBV血症（P=0.034）以及急性移植物抗宿主病（P=0.027）均与T-LGL发生有关，且多因素分析显示，良性血液病[P=0.027，OR=3.36（95%CI 1.15~9.89）]、单倍型移植[P=0.030，OR=4.67（95%CI 1.16~18.75）]、无关供者移植[P=0.041，OR=5.49（95%CI 1.10~28.16）]为移植后发生T-LGL的独立预测因素。两组患者移植后3年OS、DFS率、CIR以及NRM差异均有统计学意义[OS：100.0%对78.6%（95%CI 74.1%~83.1%），P=0.04；DFS：100.0%对70.0%（95%CI 64.9%~75.1%），P=0.01；CIR：0对16.1%（95%CI 11.8%~22.4%），P<0.01；NRM：0对12.6%（95%CI 12.5%~12.6%），P=0.02]。亚组分析结果显示，恶性疾病患者移植后发生T-LGL者预后良好，NRM、DFS率以及CIR差异均有统计学意义（P值均<0.05），而良性疾病患者移植后发生T-LGL对预后无明显影响。

结论

恶性疾病患者移植后T-LGL可能是一个较为持久的良性临床过程，与免疫重建和T细胞调节机制相关的因素可作为移植后T-LGL发生的主要预测因素。

T-Cell Dynamics in Chronic Lymphocytic Leukemia under Different Treatment Modalities

PURPOSE

Using next-generation sequencing (NGS), we recently documented T-cell oligoclonality in treatment-naïve chronic lymphocytic leukemia (CLL), with evidence indicating T-cell selection by restricted antigens.

EXPERIMENTAL DESIGN

Here, we sought to comprehensively assess T-cell repertoire changes during treatment in relation to (i) treatment type [fludarabine-cyclophosphamide-rituximab (FCR) versus ibrutinib (IB) versus rituximab-idelalisib (R-ID)], and (ii) clinical response, by combining NGS immunoprofiling, flow cytometry, and functional bioassays.

RESULTS

T-cell clonality significantly increased at (i) 3 months in the FCR and R-ID treatment groups, and (ii) over deepening clinical response in the R-ID group, with a similar trend detected in the IB group. Notably, in constrast to FCR that induced T-cell repertoire reconstitution, B-cell receptor signaling inhibitors (BcRi) preserved pretreatment clones. Extensive comparisons both within CLL as well as against T-cell receptor sequence databases showed little similarity with other entities, but instead revealed major clonotypes shared exclusively by patients with CLL, alluding to selection by conserved CLL-associated antigens. We then evaluated the functional effect of treatments on T cells and found that (i) R-ID upregulated the expression of activation markers in effector memory T cells, and (ii) both BcRi improved antitumor T-cell immune synapse formation, in marked contrast to FCR.

CONCLUSIONS

Taken together, our NGS immunoprofiling data suggest that BcRi retain T-cell clones that may have developed against CLL-associated antigens. Phenotypic and immune synapse bioassays support a concurrent restoration of functionality, mostly evident for R-ID, arguably contributing to clinical response.

Skewing of the T-cell receptor repertoire in patients receiving rituximab after allogeneic hematopoietic cell transplantation: what lies beneath?

Rituximab is known to affect T cell immune responses. We and others have reported expansions of T large granular lymphocytes (T-LGLs) in lymphoma patients after Rituximab. We report here the immunogenetic profiling of the T cell receptor (TR) gene repertoire in 14 patients who received Rituximab post allo-HCT and explore clinicobiological correlations. All experienced antigenic triggers, CMV, EBV re-activation and chronic GvHD and had been treated with Rituximab. Skewing of TRBV genes was observed: 3 TRBV genes accounted for half of the repertoire. Oligoclonal pattern with expanded clonotypes was common. Patients with oligoclonality exhibited frequently cGvHD. Longitudinal samples in one revealed distinct clonotypes, suggesting clonal drift. T-LGL leukemia of donor origin with mixed chimerism eventually developed. In conclusion, we report development of oligoclonal T-LGLs after Rituximab post allo-HCT, alluding to antigen selection. Persistence of this phenomenon likely reflects strong antigenic stimulation by viruses and/or cGVHD aggravated by Rituximab.

Spontaneous Regression of Methotrexate-related Lymphoproliferative Disorder with T-cell Large Granular Lymphocytosis

Spontaneous regression of methotrexate-related lymphoproliferative disorders (MTX-LPDs) occurs in some patients after withdrawal of MTX. However, the mechanisms by which MTX withdrawal contributes to the spontaneous regression of MTX-LPDs have not been fully elucidated. We herein show that spontaneous regression of MTX-LPDs is associated with the development of significant and transient T-cell large granular lymphocyte (T-LGL) lymphocytosis induced by MTX withdrawal. Since T-LGLs show strong cytotoxicity, their expansion may contribute to the spontaneous regression of lymphoma. Therefore, the development of T-LGL lymphocytosis maybe associated with a favorable prognosis in MTX-LPD patients.

Familial CD3+ T large granular lymphocyte leukemia: evidence that genetic predisposition and antigen selection promote clonal cytotoxic T-cell responses

CD3+ T-large granular lymphocyte (T-LGL) proliferations often present with cytopenias and splenomegaly and are linked to autoimmunity, especially rheumatoid arthritis and Felty's syndrome. We report here the intra-family occurrence of T-LGL leukemia in a father and son, both presenting with cytopenias and splenomegaly. Both patients carried the HLA-DRB1*04 allele, strongly associated with rheumatoid arthritis and Felty's syndrome, exhibited distinctive histopathological features suggestive of immune-mediated suppression of hematopoiesis and expressed a remarkably skewed T-cell receptor beta chain gene repertoire with overtime evolution (clonal drift). Immunoinformatics analysis and comparisons with clonotype sequences from various entities revealed (quasi)identities between (i) father and son, and (ii) father or son and patients with autoimmune disorders, T-LGL leukemia or chronic idiopathic neutropenia. Altogether, our results further corroborate antigen selection in the ontogeny of T-LGL leukemia and point to the interplay between genetics and the (micro)environment in shaping the outcome of cytotoxic T cell responses.