Flow Cytometry of T cells and T-cell Neoplasms

The Flow Cytometric Evaluation of B- and T-Lymphoblastic Leukemia/Lymphoma

Lymphoblastic leukemia/lymphoma, a neoplasm of precursor B or T lineage lymphoid cells, usually involves the bone marrow and peripheral blood, and may involve nodal and/or extranodal sites. The diagnosis is based on morphologic assessment, immunophenotypic analysis, usually by flow cytometry, and genetic analysis, including cytogenetics and FISH analysis, as well as molecular diagnostic analysis. This review will focus on the flow cytometric immunophenotypic findings in B- and T-lymphoblastic leukemia/lymphoma, which include expressions of early B or T cell markers, low-level expressions of CD45, as well as expressions of terminal deoxynucleotidyl transferase (TdT), and, in many cases, stem/progenitor cell marker CD34.

T-cell Receptor (TCR)-Vβ Repertoire Flow Cytometry for T-cell Lymphoproliferative Disorder: a Retrospective Analysis of a Single-Center Real-Life Laboratory Experience

Background

Discrimination between clonal and reactive cell proliferation is critical for the correct management of T-cell lymphocytosis. Multiparametric flow cytometry (MFC) represents a valuable tool, particularly because it allows the evaluation of the T-cell receptor (TCR) Vβ repertoire to pinpoint eventual clonality in T-cell lymphocytosis. A restricted expansion of a single out of the 24 evaluable families or a "clonogram-off" pattern is highly suggestive of the presence of a clonal T-cell population. However, data available on the concordance between MFC TCR-Vβ repertoire and molecular analysis of TCR gene rearrangements, which is regarded as the gold standard for assessing T-cell clonality, are limited.

Objective and methods

We performed a retrospective monocentric study involving 307 patients referred to our center for lymphocytosis between 2003 and 2024. The aim of our study was to investigate the diagnostic accuracy of MFC TCR-Vβ repertoire analysis and compare its performance with molecular analysis of TCR gene rearrangements for the identification of T-cell clonality.

Results

In clonally restricted cases, MFC TCR-Vβ repertoire analysis demonstrated a restricted expansion of a single Vβ family in 67.5% of cases, while a "clonogram-off" pattern inferred clonality in the remaining 32.5%. For 215 (70%) patients, both MFC TCR-Vβ repertoire analysis and molecular analysis of TCR gene rearrangements were available, showing an absolute concordance (215 out of 215 cases, 100%) between the two methods.

Conclusion

MFC TCR-Vβ repertoire analysis is a rapid, cheap, sensitive, and reliable tool to identify clonal T-cell lymphocytosis. It represents an absolutely valid first-line diagnostic approach, and it should be included in the routine laboratory work-up performed on MFC analysis for peripheral lymphocytosis.

19-color, 21-Antigen Single Tube for Efficient Evaluation of B- and T-cell Neoplasms

Non-Hodgkin lymphoma (NHL) is a heterogeneous disease, encompassing a wide variety of individually distinct neoplastic entities of mature B-, T-, and NK-cells. While they constitute a broad category, they are the most common hematologic malignancies in the world. The distinction between different neoplastic entities requires a multi-modal approach, such as flow cytometric immunophenotyping, which can exclude a neoplastic proliferation and help narrow the differential diagnosis. This article describes a flow cytometric test developed at Memorial Sloan Kettering Cancer Center to assess B-, T-, and NK-cells in a single tube, 21-antibody, 19-color assay. The assay can identify most B- and T-cell NHLs with high specificity and sensitivity and significantly narrow the differential when a specific diagnosis cannot be made. The basic protocol provides a detailed operational procedure for sample processing, staining, and cytometric acquisition. The support protocol provides typical steps and caveats for data analysis in lymphoproliferative disorders and in discriminating a variety of specific disease entities from each other and normal lymphoid populations. © 2023 Wiley Periodicals LLC. Basic Protocol: Processing, staining, and cytometric analysis of samples for B- and T-cell assessment Support Protocol: Analysis and interpretation of the B- and T-cell lymphocyte assay.

Pediatric T-cell acute lymphoblastic leukemia blast signature and MRD associated immune environment changes defined by single cell transcriptomics analysis

Different driver mutations and/or chromosomal aberrations and dysregulated signaling interactions between leukemia cells and the immune microenvironment have been implicated in the development of T-cell acute lymphoblastic leukemia (T-ALL). To better understand changes in the bone marrow microenvironment and signaling pathways in pediatric T-ALL, bone marrows collected at diagnosis (Dx) and end of induction therapy (EOI) from 11 patients at a single center were profiled by single cell transcriptomics (10 Dx, 5 paired EOI, 1 relapse). T-ALL blasts were identified by comparison with healthy bone marrow cells. T-ALL blast-associated gene signature included SOX4, STMN1, JUN, HES4, CDK6, ARMH1 among the most significantly overexpressed genes, some of which are associated with poor prognosis in children with T-ALL. Transcriptome profiles of the blast cells exhibited significant inter-patient heterogeneity. Post induction therapy expression profiles of the immune cells revealed significant changes. Residual blast cells in MRD+ EOI samples exhibited significant upregulation (P < 0.01) of PD-1 and RhoGDI signaling pathways. Differences in cellular communication were noted in the presence of residual disease in T cell and hematopoietic stem cell compartments in the bone marrow. Together, these studies generate new insights and expand our understanding of the bone marrow landscape in pediatric T-ALL.

Surface CD3-negative monomorphic epitheliotropic intestinal T-cell lymphoma

Intestinal T/NK-cell lymphomas include enteropathy-associated T-cell lymphoma (EATL), monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL), indolent T-cell lymphoproliferative disorders of the GI tract (ITCLPD), extranodal NK/T-cell lymphoma, nasal type (ENKTL), and intestinal T-cell lymphoma NOS (ITCL-NOS). Here we describe a case of surface CD3-negative MEITL. A 63-year-old Japanese female had a tumor located in the conglomerated ileum, which formed multiple mass lesions. The resected tissue showed a diffuse infiltration of monomorphic medium-sized lymphocytes with epitheliotropism. Flowcytometry using a fresh specimen of the tumor revealed positivity for CD7, CD8, CD38, and CD56, but not surface CD3. On immunohistochemistry, the tumor showed positivity for cytoplasmic CD3, CD8, CD56, TIA-1, Granzyme B, and perforin. EBER with in situ hybridization was negative. Moreover, H3K36me3, which is negative in MEITL with SETD2-mutation, was positive. This is an important case of MEITL due to its oncogenesis.

Diagnostic utility of the aberrant immunohistochemical expression of CD3 molecules for peripheral T-cell lymphomas

The histological diagnosis of peripheral T-cell lymphomas (PTCLs) is often challenging. Flow cytometry (FCM) sometimes shows the loss of pan-T-cell markers for PTCLs, suggesting the neoplastic nature of these cells. Immunohistochemically, the total loss of pan-T-cell markers has been demonstrated in PTCLs. Furthermore, except for the total loss, the aberrant immunohistochemical expressions of pan-T-cell markers have also been empirically observed in PTCLs, but the details remain unexamined. Therefore, the present study semi-quantitatively evaluated the aberrant expression of cytoplasmic CD3ε (cCD3ε), the most common immunohistochemical pan-T-cell marker, in 91 PTCL cases. The expressions of the other CD3 molecules, CD3δ, CD3γ, and CD3ζ were also examined. Frequencies of the total immunohistochemical loss of CD3 molecules and loss of surface CD3ε (sCD3ε) in FCM were analyzed for comparison. The results showed atypical, aberrant expression patterns for immunohistochemical CD3 molecules: perinuclear, cytoplasmic, membranous, and partial negative. The frequency of each molecule was as follows: cCD3ε 40.7 %, CD3δ 26.4 %, CD3γ 53.8 %, and CD3ζ 54.9 %, especially the latter two showed high frequency in peripheral T-cell lymphoma, not otherwise specified, angioimmunoblastic T-cell lymphoma, and adult T-cell lymphoma/leukemia. Immunohistochemical total loss was less than aberrant expression in all CD3 molecules, with the frequency of cCD3ε being the lowest (6.6 %). The loss of sCD3ε in FCM was observed in 43.3 % of cases, with a similar frequency to the aberrant expression of cCD3ε. In conclusion, the aberrant immunohistochemical expression of cCD3ε was a useful finding as is sCD3ε loss in FCM, but CD3γ and CD3ζ were more useful, facilitating the diagnosis of PTCLs.

Two-way detection of image features and immunolabeling of lymphoma cells with one-step microarray analysis

Detecting the number of pathological lymphoma cells and lymphocyte subtypes in blood is helpful for clinical diagnosis and typing of lymphoma. In the current study, cell type is identified by cell morphological features and immunolabeled lymphocyte subtypes. Red blood cells and leukocytes were separated using a microfluidic cell chip based on physical blood cell parameters, and leukocytes were identified using five characteristic parameters: energy variance, entropy variance, moment of inertia variance, color mean, and cell area individually. The number of red blood cells that could come into contact with the leukocyte membrane was ≤2 based on the microfluidic injection flow rate of microfluidic chips. Anti-CD3 and anti-CD19 antibodies were used for immunofluorescence staining of T-lymphocyte and B-lymphocyte surface antigens, respectively. The results suggested that the microfluidic assay could detect lymphocyte surface antigen markers and intact leukocytes. Therefore, we report a one-step microfluidic chip for classifying hematological lymphoma cells based on the physical parameters of cells, which can simultaneously measure the overall morphology of blood cells and immunolabeling of lymphocyte surface antigens in one step, solving the current problem of detecting subtypes of hematological lymphoma cells based on multiple methods and multi-step detection.