High-Sensitive TRBC1-Based Flow Cytometric Assessment of T-Cell Clonality in Tαβ-Large Granular Lymphocytic Leukemia

Noemí Muñoz-García; F Javier Morán-Plata; Neus Villamor; Margarida Lima; Susana Barrena; Sheila Mateos; Carolina Caldas; Jacques J M van Dongen; Alberto Orfao; Julia Almeida

doi:10.3390/cancers14020408

High-Sensitive TRBC1-Based Flow Cytometric Assessment of T-Cell Clonality in Tαβ-Large Granular Lymphocytic Leukemia

Cancers (Basel). 2022 Jan 14;14(2):408. doi: 10.3390/cancers14020408.

Authors

Noemí Muñoz-García^{1

2}, F Javier Morán-Plata^{1

2}, Neus Villamor^{2

3}, Margarida Lima^{4

5}, Susana Barrena^{1

2}, Sheila Mateos^{1

2}, Carolina Caldas^{1

2}, Jacques J M van Dongen^{1

6}, Alberto Orfao^{1

2}, Julia Almeida^{1

2}

Affiliations

¹ Translational and Clinical Research Program, Centro de Investigación del Cáncer and IBMCC (CSIC-University of Salamanca), Cytometry Service, NUCLEUS, Department of Medicine, University of Salamanca (USAL) and Institute of Biomedical Research of Salamanca (IBSAL), 37007 Salamanca, Spain.
² Biomedical Research Networking Centre Consortium of Oncology (CIBERONC), Instituto de Salud Carlos III, 28029 Madrid, Spain.
³ Department of Pathology, Hematopathology Unit, Hospital Clínic, IDIBAPS, 08036 Barcelona, Spain.
⁴ Department of Hematology, Laboratory of Cytometry, Hospital de Santo António, Centro Hospitalar do Porto, 4099-001 Porto, Portugal.
⁵ Unit for Multidisciplinary Research in Biomedicine (UMIB), Abel Salazar Institute of Biomedical Sciences (ICBAS), University of Porto, 4050-313 Porto, Portugal.
⁶ Department of Immunology, Leiden University Medical Center (LUMC), 2333 Leiden, The Netherlands.

Abstract

Flow cytometric (FCM) analysis of the constant region 1 of the T-cell receptor β chain (TRBC1) expression for assessing Tαβ-cell clonality has been recently validated. However, its utility for the diagnosis of clonality of T-large granular lymphocytic leukemia (T-LGLL) needs to be confirmed, since more mature Tαβ cells (i.e., T-LGL normal-counterpart) show broader TRBC1⁺/TRBC1^- ratios vs. total Tαβ cells. We compared the distribution and absolute counts of TRBC1⁺ and TRBC1^- Tαβ-LGL in blood containing polyclonal (n = 25) vs. clonal (n = 29) LGL. Overall, polyclonal TRBC1⁺ or TRBC1^- Tαβ-LGL ranged between 0.36 and 571 cells/μL (3.2-91% TRBC1⁺ cells), whereas the clonal LGL cases showed between 51 and 11,678 cells/μL (<0.9% or >96% TRBC1⁺ cells). Among the distinct TCRVβ families, the CD28^- effector-memory and terminal-effector polyclonal Tαβ cells ranged between 0 and 25 TRBC1⁺ or TRBC1^- cells/μL and between 0 and 100% TRBC1⁺ cells, while clonal LGL ranged between 32 and 5515 TRBC1⁺ or TRBC1^- cells/μL, representing <1.6% or >98% TRBC1⁺ cells. Our data support the utility of the TRBC1-FCM assay for detecting T-cell clonality in expansions of Tαβ-LGL suspected of T-LGLL based on altered percentages of TRBC1⁺ Tαβ cells. However, in the absence of lymphocytosis or in the case of TαβCD4-LGL expansion, the detection of increased absolute cell counts by the TRBC1-FCM assay for more accurately defined subpopulations of Tαβ-LGL-expressing individual TCRVβ families, allows the detection of T-cell clonality, even in the absence of phenotypic aberrations.

Keywords: JOVI-1; LGL; LGLL; TCRVβ repertoire; TRBC1; Tαβ effector cells; Tαβ-cell maturation stages; flow cytometry T-cell clonality assessment; large granular lymphocytes; large granular lymphocytic leukemia.

Abstract

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