T-cell Receptor Gene Rearrangement Research Articles

Clustering Algorithm-Driven Detection of TRBC1-Restricted Clonal T-Cell Populations Produces Better Results than Manual Gating Analysis.

Flow cytometric (FC) immunophenotyping and T-cell receptor (TCR) gene rearrangement studies are essential ancillary methods for the characterisation of T-cell lymphomas. Traditional manual gating and polymerase chain reaction (PCR)-based analyses can be labour-intensive, operator-dependent, and have limitations in terms of sensitivity and specificity. The objective of our study was to investigate the efficacy of the Phenograph and t-SNE algorithms together with an antibody specific for the TCR β-chain constant region 1 (TRBC1) to identify monoclonal T-cell populations. FC- and PCR-based clonality analyses were performed on 275 samples of T-cell lymphomas, B-cell lymphomas, and reactive lymphocytic proliferations. Monotypic T-cell populations were identified in 65.1% of samples by manual gating and 72.4% by algorithm-driven analysis, while PCR-based analysis detected clonal T cells in 68.0%. Of the 262 monotypic populations identified, 46.6% were classified as T-cell lymphomas and 53.4% as T-cell populations of uncertain significance (T-CUS). Algorithm-driven gating identified monotypic populations that were overlooked by manual gating or PCR-based methods. The study highlights the difficulty in distinguishing monotypic populations as T-cell lymphoma or T-CUS. Further research is needed to establish criteria for distinguishing between these populations and to improve FC diagnostic accuracy.

Clinically assessed mycosis fungoides tumor burden index as a prognostic marker in tumor-stage mycosis fungoides: a retrospective cohort study.

Prognostic markers are needed for tumor-stage mycosis fungoides (MF) because of their variable prognosis. The objectives of this study were to explore prognostic markers for tumor-stage MF and assess the prognostic significance of clinically assessed MF tumor burden index (MTBI). MTBI was devised to consider the tumor size ≥ 2cm, number ≥ 5, ulcers, and body surface area ≥ 50%. The prognostic value of MTBI and other potential markers derived from blood tests and skin biopsy were evaluated retrospectively using a tertiary medical center database. We included 38 cases of tumor-stage MF. The mean age was 52.1 years, and the male-to-female ratio was 2.5:1. In multivariable analysis, MTBI ≥ 3 (adjusted hazard ratio, 9.41; 95% confidence interval, 1.13-78.15) was significantly associated with worse disease-specific survival. Ulcers were the only MTBI constituent significantly associated with survival. Among other markers, elevated lactate dehydrogenase level was associated with a worse disease-specific survival. Neutrophil-lymphocyte-ratio, pan-inflammation-value, CD30 positivity, Ki-67 index, large cell transformation, and monoclonal T-cell receptor gene rearrangement were not associated with prognosis. In conclusion, MTBI is useful and promising prognostic marker for tumor-stage MF.

Mycosis Fungoides: Histopathology and T Cell Receptor Gene Rearrangements in Indian Patients

Introduction: Mycosis fungoides (MF) is the commonest cutaneous T cell lymphoma. MF presents in three stages the patch, plaque, and tumor. The distinction of patch-stage MF from inflammatory dermatoses is a diagnostic challenge. Need for the Study: MF shows T cell receptor gamma and beta gene rearrangements (TCRG and TCRB), detectable by polymerase chain reaction (PCR). Data about the clonality of infiltrates in our population and their utility in diagnosis is lacking. Materials and Methods: Skin biopsies from 50 patients with mycosis fungoides from January 2007 to July 2015 were studied for microscopic features. TCR gamma and beta gene rearrangement assays were performed on 14 patients where formalin fixed paraffin embedded (FFPE) was available. DNA was extracted using the phenol-chloroform method. PCR was performed using primers from Invivoscribe Identiclone assay. Clonality was analyzed using Agarose gel electrophoresis. Results: Of the 50 cases, 37 were patch, nine were plaque, and four were tumor stage. All cases showed disproportionate lymphocyte epidermotropism, 38 showed lymphocyte atypia, and 33 showed adnexotropism (11 eccrotropism and 22 folliculotropism). Clonality was assessed in 14 cases. Of these, 3/9 patch stages were monoclonal (1/3 monoclonal for beta, and 2/3 monoclonal for gamma and beta). 3/3 plaque stage MF was monoclonal (1/3 for gamma, 2/3 for both), and 1/2 tumor stage MF was monoclonal for gamma and beta receptors. Conclusion: The patch stage was the most common presentation. TCR gene rearrangements were noted in 50% of MF, with TCR gamma rearrangements being more common. Plaque and tumor stages yielded higher positive rates.

Clinical Analysis of CD4+CD8- T-Cell Large Granular Lymphocytic[JP] Leukemia

To investigate the clinical characteristics and treatment of patients with CD4+CD8- T-cell large granular lymphocytic leukemia (T-LGLL). The clinical manifestations, diagnosis and treatment of 1 case of CD4+CD8- T-LGLL patient were reported, and relevant literatures were reviewed. The patient was a 70-year-old woman with slow clinical progress, mainly manifested by thrombocytopenia and myelodysplasia. The blood smear was mainly composed of large granular lymphocytes. Immunotyping and T-cell receptor gene rearrangement analysis showed that it was in line with T-LGLL. Partial remission(PR) was achieved through the treatment of cyclophosphamide(50 mg/d) combined with prednisone(gradually reduced and stopped later). CD4+CD8- T-LGLL is very rare in clinical practice, and its clinical manifestations are different from those of CD4-CD8+ T-LGLL.

Autoregulated splicing of TRA2β programs T cell fate in response to antigen-receptor stimulation.

T cell receptor (TCR) sensitivity to peptide-major histocompatibility complex (MHC) dictates T cell fate. Canonical models of TCR sensitivity cannot be fully explained by transcriptional regulation. In this work, we identify a posttranscriptional regulatory mechanism of TCR sensitivity that guides alternative splicing of TCR signaling transcripts through an evolutionarily ultraconserved poison exon (PE) in the RNA-binding protein (RBP) TRA2β in mouse and human. TRA2β-PE splicing, seen during cancer and infection, was required for TCR-induced effector T cell expansion and function. Tra2β-PE skipping enhanced T cell response to antigen by increasing TCR sensitivity. As antigen levels decreased, Tra2β-PE reinclusion allowed T cell survival. Finally, we found that TRA2β-PE was first included in the genome of jawed vertebrates that were capable of TCR gene rearrangements. We propose that TRA2β-PE splicing acts as a gatekeeper of TCR sensitivity to shape T cell fate.

Isolated Monoclonal T-Cell Receptor Gene Rearrangement in a Lung Adenocarcinoma Harboring MET Exon 14 Skipping: Diagnostic Pitfall.

In the diagnostic workup of poorly differentiated tumors, T-cell receptor (TCR) clonality has long been considered as evidence of T-cell lymphoma. MET exon 14 skipping (METex14) is a mutation typically seen in lung adenocarcinoma. Herein, we present the first report of METex14 lung adenocarcinoma with isolated monoclonal TCRγ gene rearrangement. A 69-year-old woman presented to an outside hospital with pleural effusions. A pleural decortication demonstrated malignant cells positive for CD30 and CD138 but negative for BerEP4, KRT5, and EMA. An equivocal HHV8 staining was interpreted as positive, leading to the erroneous outside diagnosis of primary effusion lymphoma. Additional workup at our institution revealed a lack of HHV8 and T-cell markers but the presence of TCRγ clonality, pankeratin, and TTF1 expression. Repeat TCRγ testing on the in-house biopsy was negative for clonality. Next-generation sequencing detected METex14, confirming the diagnosis of lung adenocarcinoma. The potential diagnostic pitfall and prognostic/predictive implications are discussed.

Assessing T-cell receptor clonality by next-generation sequencing in atypical cutaneous lymphoid infiltrates and cutaneous T-cell lymphoma: A scoping review.

The diagnosis of cutaneous T-cell lymphoma (CTCL) remains challenging. Demonstration of a clonal T-cell population using T-cell receptor (TCR) gene rearrangement studies by next-generation sequencing (NGS) has been explored in several studies. This review summarizes the current literature on NGS-based sequencing methods for the assessment of TCR clonality in the evaluation of atypical cutaneous lymphoid infiltrates and CTCL on behalf of the American Society of Dermatopathology Appropriate Use Criteria Committee (lymphoproliferative subgroup). PubMed was searched for relevant articles, including CTCL and NGS, for clonality from 1967 to 2022. Thirteen studies were included in the analysis. The skin was the most commonly assayed compartment with TCR NGS. Sensitivity for TCR NGS in the skin ranged between 69% and 100%, compared to 44%-72% for polymerase chain reaction (PCR)-capillary electrophoresis. Specificity for TCR NGS in the skin ranged from 86% to 100%, compared to 77%-88% for PCR capillary electrophoresis. TCR NGS was also reported to have potential prognostic value in CTCL and can also be used to detect relapse and/or minimal residual disease after treatment.

Clinicopathological features of primary mucosal CD30-positive T-cell lymphoproliferative disorders

Objective: To investigate the clinicopathological features and differential diagnosis of primary mucosal CD30-positive T-cell lymphoproliferative disorders (pmCD30+TLPD). Methods: Eight cases of pmCD30+TLPD diagnosed from 2013 to 2023 at the Department of Pathology, Beijing Friendship Hospital Affiliated to Capital Medical University and Beijing Ludaopei Hospital were retrospectively collected. The immunophenotype, EBV infection status and T-cell receptor (TCR) clonability of tumor cells were examined. The clinicopathological features were analyzed and related literatures were reviewed. Results: There were 5 females and 3 males, aged 28 to 73 years, without B symptoms, lack of trauma and autoimmune diseases. Seven cases occurred in oral mucosa and one in anal canal mucosa. Submucosal nodules with ulcerations were presented in all cases except one, which only submucosal nodule. Morphologically, there was different distribution of allotypic lymphocytes in inflammatory background. Four cases showed "kidney-shaped", "embryonic" and "horseshoe-shaped" cells, and one case resembled Hodgkin and Reed/Sternberg (HRS) cells. Allotypic lymphocytes expressed CD3 (7/8), CD4+/CD8-(7/8) and CD4-/CD8-(1/8). CD30 was uniformly strongly positive while ALK and CD56 were negative. In situ hybridization of EBER was negative in five cases (5/5). Clonal TCR gene rearrangement was positive in two cases. Four patients did not receive radiotherapy or chemotherapy. All the seven patients survived without disease except one died due to concurrent leukopenia. Conclusions: pmCD30+TLPD had a broad morphological spectrum and could be easily confused with primary cutaneous CD30+TLPD and systemic ALK-negative anaplastic large cell lymphoma involving mucosa, which may lead to misdiagnosis. Although the majority of the cases had a favorable prognosis, a few cases relapsed or progressed to lymphoma.

Infectious mononucleosis complicated by transitory Epstein-Barr virus infection of T and natural killer cells

Epstein-Barr virus (EBV) typically infects B cells in infectious mononucleosis (IM), but a rare case shows EBV infection in T cells. Seven cases of lymphoproliferative disorder caused by EBV-positive cytotoxic T/natural killer (NK) cell proliferation in the lymph nodes, termed IM with transient EBV infection of T and NK cells (EBV + T/NK cells in IM), are reported here. The purpose of the study is to describe clinicopathological features of EBV + T/natural killer (NK) cells in IM of the lymph node. We retrospectively analysed seven cases of Chinese children and young people adults with EBV + T/NK cells in IM. We used morphological observation, immunohistochemical staining, EB virus in situ hybridisation detection, and analysis of T-cell receptor gene rearrangement. The patients were healthy prior to illness, experiencing sudden onset occurring in all the patients, with high fever as the first symptom, followed by lymphadenopathy and hepatosplenomegaly. Diagnosis occurred < 1.5 months of symptom onset. Most lymphocytes in lesions expressed CD3 and Granzyme B or TIA-1 and lacked CD5. CD56 was expressed in numerous cells in 5 of the 7 cases. EBV-encoded RNA (EBER) was detected in medium-to-large-sized cells (50–100 cells per cell/high-power field). T-cell receptor (TCR) gene rearrangement was seen in six cases, with monoclonal rearrangement in four cases. Treatment was conservative treatment but not chemotherapy. Four received anti-HLH therapy and others anti-inflammatory treatment. All patients survived with relapse after long-term clinical observation and follow-up. EBV + T/NK cells in IM can elicit malignant features that mimic T/NK-cell lymphoma pathologically and benign features mimicking IM clinically. These findings indicate that EBV + T/NK cells in IM could serve as valuable diagnosis. Additional clinical information, including age of onset (children and young people), nature of onset (sudden), disease course (short), symptoms (systemic), EBV infection status (acute), and lymph node involvement, is crucial for accurate diagnosis and prognostic evaluation.

Comprehensive Flow Cytometric, Immunohistologic, and Molecular Assessment of Thymus Function in Rhesus Macaques.

The critical importance of the thymus for generating new naive T cells that protect against novel infections and are tolerant to self-antigens has led to a recent revival of interest in monitoring thymic function in species other than humans and mice. Nonhuman primates such as rhesus macaques (Macaca mulatta) provide particularly useful animal models for translational research in immunology. In this study, we tested the performance of a 15-marker multicolor Ab panel for flow cytometric phenotyping of lymphocyte subsets directly from rhesus whole blood, with validation by thymectomy and T cell depletion. Immunohistochemical and multiplex RNA expression analysis of thymus tissue biopsies and molecular assays on PBMCs were used to further validate thymus function. Results identify Ab panels that can accurately classify rhesus naive T cells (CD3+CD45RA+CD197+ or CD3+CD28+CD95-) and recent thymic emigrants (CD8+CD28+CD95-CD103+CD197+) using just 100 µl of whole blood and commercially available fluorescent Abs. An immunohistochemical panel reactive with pan-cytokeratin (CK), CK14, CD3, Ki-67, CCL21, and TdT provides histologic evidence of thymopoiesis from formalin-fixed, paraffin-embedded thymus tissues. Identification of mRNAs characteristic of both functioning thymic epithelial cells and developing thymocytes and/or molecular detection of products of TCR gene rearrangement provide additional complementary methods to evaluate thymopoiesis, without requiring specific Abs. Combinations of multiparameter flow cytometry, immunohistochemistry, multiplex gene expression, and TCR excision circle assays can comprehensively evaluate thymus function in rhesus macaques while requiring only minimal amounts of peripheral blood or biopsied thymus tissue.

Morphoea presenting histopathologically as mycosis fungoides: an illustrative series of four cases.

There have been exceptional reports of morphoea presenting with epidermal changes overlapping histopathologically with cutaneous Tcell lymphoma of the mycosis fungoides type (MF). This phenomenon gives rise to an ambiguous clinicopathological scenario in which distinguishing these conditions may be challenging. The aim of this study is to characterise the clinical, histopathological and molecular findings of this phenomenon through a case series. Four patients with classical clinical presentation of morphoea but unusual histopathology displaying typical findings of morphoea, together with intra-epidermal CD8 positive lymphocytes indistinguishable from MF, were identified. The clinical phenotypes of morphoea were varied, and they all presented early in the active phase of the disease. They all exhibited intra-epidermal lymphocytes with tagging and cytological atypia. Pautrier-like microabscesses were also seen. Using molecular analysis, two cases showed clonal TCR gene rearrangement. Follow-up of all cases has been consistent with classical morphoea. Early morphoea can seldom present with atypical clonal intra-epidermal lymphocytes indistinguishable from MF. The fact that these changes can occur in several different clinical subtypes of morphoea raises the possibility that this could be a pattern of inflammation in early disease more common than currently appreciated.

Monomorphic T-cell post-transplant lymphoproliferative disorder with features of HHV8-negative primary effusion lymphoma: an autopsy case and review of the literature

A 67-year-old man underwent renal transplantation in his twenties. He developed refractory pleural effusion, with many large lymphocytes with severe atypia and mitosis in the effusion, indicating malignant lymphoma. He finally died of respiratory failure. An autopsy revealed atypical lymphocytes positive for CD3, CD4, and CD30 and negative for CD8, CD20, PAX5, human herpesvirus (HHV) 8, and Epstein–Barr virus-encoded small RNAs by immunohistochemistry and in situ hybridization. Atypical lymphocytes also had T-cell receptor gene rearrangements Jβ2, Jγ2, and Jδ1 and chromosomal aberrations der(8)t(1;8)(q21;p21), add(13)(q12), add(14)(q32), and add(16)(q12-13). A few atypical lymphocytes were present at other sites. We finally diagnosed this case as monomorphic T-cell post-transplant lymphoproliferative disorder with features of HHV8-negative primary effusion lymphoma. A literature review only identified six cases (four HHV8-negative, two HHV8-positive) of effusion lymphoma of T-cell type, including the present case. Interestingly, about half of HHV8-negative and HHV8-positive cases had a history of renal transplantation in their twenties. All cases showed tumor CD30 expression, whereas CD4 and CD8 expressions were inconsistent. These findings indicated that this lymphoma may be associated with post-transplant lymphoproliferative disorder by renal transplantation at a young age, although further cases need to be analyzed.

Analysis of measurable residual disease by IG/TR gene rearrangements: quality assurance and updated EuroMRD guidelines.

Minimal/measurable residual disease (MRD) diagnostics using real-time quantitative PCR analysis of rearranged immunoglobulin and T-cell receptor gene rearrangements are nowadays implemented in most treatment protocols for patients with acute lymphoblastic leukemia (ALL). Within the EuroMRD Consortium, we aim to provide comparable, high-quality MRD diagnostics, allowing appropriate risk-group classification for patients and inter-protocol comparisons. To this end, we set up a quality assessment scheme, that was gradually optimized and updated over the last 20 years, and that now includes participants from around 70 laboratories worldwide. We here describe the design and analysis of our quality assessment scheme. In addition, we here report revised data interpretation guidelines, based on our newly generated data and extensive discussions between experts. The main novelty is the partial re-definition of the "positive below quantitative range" category by two new categories, "MRD low positive, below quantitative range" and "MRD of uncertain significance". The quality assessment program and revised guidelines will ensure reproducible and accurate MRD data for ALL patients. Within the Consortium, similar programs and guidelines have been introduced for other lymphoid diseases (e.g., B-cell lymphoma), for new technological platforms (e.g., digital droplet PCR or Next-Generation Sequencing), and for other patient-specific MRD PCR-based targets (e.g., fusion genes).

Quantifying how TCR sequence influences cell fate commitment in chronic LCMV infection

Abstract Repetitive T cell receptor (TCR) engagement on CD8 T cells during chronic infection is a critical driver of the dysfunctional state termed exhaustion. These exhausted cells are characterized by additional heterogeneity including a memory-like progenitor cell (Tpro) that continuously gives rise to either non-cytolytic exhausted cells (Texh) or cytotoxic effector cells (Teff). While we and others have shown that TCR avidity influence cell fate commitment to Texh or Teff, it is not certain if TCR sequence features influence this fate choice. In this study, we identify how TCR V(D)J gene recombination influences T cell differentiation at the single-cell resolution. To investigate this, we performed single-cell resolution TCR sequencing (scTCR-seq) on GP33+ tetramer sorted cells within lymphocytic choriomeningitis virus (LCMV) Clone 13 model of chronic infection across 7 different mice. Utilizing TCRdist and Clonotype Neighbor Graph Analysis (CoNGA), we construct correlations between gene expression and TCR features. We find that both chain usage and cdr3 motifs correlate to effector or exhausted cell fate commitment across these different mice. Overall, our results suggest that TCR gene rearrangement is critical not only for antigen specificity, but also determining CD8 T cell phenotypic outcomes during chronic viral infection.

Streamlined 96-well plate method for simultaneous single-cell TCR immune receptor repertoire analysis and immunophenotyping

Abstract This study describes an efficient immune profiling method by FACS-sorting single cells in a 96-well plate to assess clonotype repertoire diversity, paired-chain information, and cell phenotypes in a single, multiplex RT-PCR-based assay without the use of any specialized equipment. It is a cost-effective alternative to conventional single-cell technologies such as microwell arrays or droplet microfluidics. The 96-well plate contains primers for either T-cell receptor (TCR) / or TCR / chains, together with primers for 30 key T-cell markers. T cells from PBMCs are sorted in a single-cell-per-well format. We conduct RT-PCR library prep using the DriverMapTM Adaptive Immune Receptor (AIR) Repertoire Profiling Assay and sequence the CDR3 region. The results show clonotype frequencies, chain pairing details for / and / chains, and T-cell subtype classifications based on gene expression profiling. This enables in-depth analysis of TCR gene rearrangements at the single-cell level, enhancing understanding of T cell development, proliferation, and clonality, which are important in studying cancer, immunodeficiencies, and autoimmune disorders. Additionally, we can effectively identify and characterize γδ T cells by integrating single-cell TCR sequencing with RNA sequencing data, potentially useful in the development of γδ cancer immunotherapies. Overall, this method provides an efficient way to simultaneously analyze clonotypes and immunophenotypes in a single assay.

Detecting T-cell receptor clonality in patients with severe atopic dermatitis refractory to dupilumab.

Trials and real-life studies demonstrated clinically meaningful improvements of disease activity in the majority of patients with moderate to severe atopic dermatitis (AD) treated with the anti-IL-4RA-antibody dupilumab. However, misdiagnosis or confounding skin diseases in particular cutaneous T-cell lymphoma (CTCL) may lead to inadequate response. To investigate the clinical and pathological features of patients with AD who showed insufficient response to dupilumab. We reviewed the medical records of 371 patients treated with dupilumab for severe AD. Insufficient response was defined as failure to achieve an improvement of the eczema area severity index (EASI) of at least 50% (EASI-50) at Week 16 and of 75% (EASI-75) at Week 52. Among 46 patients with insufficient response, 35 patients consented to a re-evaluation including a full physical exam, biopsies and laboratory assessments including immunohistochemistry and T-cell receptor gene rearrangement analysis to differentiate CTCL. Of the 371 patients treated with dupilumab, 46 (12.3%) patients showed insufficient response to dupilumab. Of these, 35 underwent further evaluation, and 19 (54.2% of inadequate responders) were finally diagnosed with mycosis fungoides (MF). In these patients, transition to or addition of conventional MF treatment led to clinical improvements. Insufficient response to dupilumab treatment may help uncover early MF on an existing AD background.

Clinicopathological and molecular genetic alterations in monomorphic–epitheliotropic intestinal T-cell lymphoma of the small intestine

BackgroundSmall intestinal monomorphic–epitheliotropic intestinal T-cell lymphoma (MEITL) is a rare aggressive T-cell lymphoma originating in the gastrointestinal tract. This study aimed to investigate the clinicopathological features, immunophenotypes, and molecular genetic changes of MEITL.MethodsThe clinicopathological data for three patients with surgically resected MEITL of the small intestine were collected. Next, immunohistochemical labeling, Epstein–Barr virus (EBV) in situ hybridization, assessment of clonal rearrangement of T-cell receptor (TCR) genes, and next-generation sequencing (NGS) were performed.ResultsOf the three patients, two were male and one was female, with ages of 61, 67, and 73 years, respectively. Clinical manifestations were predominantly abdominal pain and distension. Histopathology revealed infiltrative growth of small-to-medium-sized lymphocytes with a consistent morphology between the intestinal walls, accompanied by an obvious pro-epithelial phenomenon. The expression of CD3, CD8, CD43, CD56, TIA-1, CD103, H3K36me3, and Bcl-2 was detected, and the Ki-67 proliferation index ranged from 50% to 80%. All three patients tested negative for EBER. However, monoclonal rearrangement of the TCR gene was detected in them. NGS testing showed a JAK3 mutation in all three cases. Further, STAT5B, SETD2, and TP53 mutations were each observed in two cases, and a BCOR mutation was found in one case. All patients were treated with chemotherapy after surgery. Two patients died 7 and 15 month post-operation, and one patient survived for 5 months of follow-up.ConclusionsOur findings demonstrate that mutations in JAK3 and STAT5B of the JAK/STAT pathway and inactivation of the oncogene SETD2 markedly contribute to the lymphomagenesis of MEITL.

Abstract 3976: Single-cell TCRɑ/β and TCRγ/δ immune receptor profiling and immunophenotyping using a 96-well plate sorted-cell approach

Abstract Single-cell immune receptor profiling is a revolutionary approach that allows investigators to combine clonotype repertoire identification with paired-chain information and the phenotype of cells (e.g., cell subtype). Single-cell immune receptor profiling can be performed using a medium-throughput approach (1,000-5,000 cells) using microwell arrays or droplet microfluidics technologies. However, these assays are more complicated to run and require expensive reagents and limited sequencing throughput when compared to bulk immune receptor profiling methods. Here, we describe a low-throughput, single-cell immune profiling strategy using sorted cells in 96-well plates. The plate is pre-aliquoted with either T-cell receptor (TCR) ɑ/β or TCR γ/δ primers along with 30 crucial T-cell markers. We perform multiplex RT-PCR amplification and sequencing of the CDR3 regions. The resulting data provides the abundant clonotype counts along with the chain pairing information for these ɑ/β and γ/δ chains, together with the T-cell subtype information using gene-expression profiles. By analyzing the TCR gene rearrangement at the single-cell level, researchers can better understand T cell development, proliferation, and clonality, which are crucial for studying diseases such as cancer, immunodeficiency, and autoimmunity. Furthermore, single-cell TCR sequencing when combined with RNA sequencing datasets, facilitates the identification of γδ T cells. This method provides a standardized tool for identifying potential γδ T cell-based cancer immunotherapies. The technology's cost-effectiveness and ability to analyze clonotypes and immunophenotypes of cells in a single assay make it a valuable tool for unraveling the immune dynamics in various diseases. Citation Format: Alex Chenchik, Tianbing Liu, Mikhail Makhanov, Dongfang Hu, Lester Kobzik, Khadija Ghias, Paul Diehl. Single-cell TCRɑ/β and TCRγ/δ immune receptor profiling and immunophenotyping using a 96-well plate sorted-cell approach [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3976.

Cutaneous lymphoproliferative disorders: Back to the future.

In the 1980s, immunohistochemistry and clonality analyses became instrumental in the recognition and definition of new types of cutaneous T-cell lymphoma (CTCL) and cutaneous B-cell lymphoma (CBCL) and the development of new classifications. By accepting loss of pan-T-cell antigens and clonal T-cell receptor gene rearrangements as important criteria to differentiate between benign and malignant T-cell proliferations, and monotypic immunoglobulin light-chain expression and clonal immunoglobulin gene rearrangements as crucial criteria to distinguish between benign and malignant B-cell proliferations, many cases, until then diagnosed as cutaneous lymphoid hyperplasia or pseudolymphoma, were reclassified as primary cutaneous CD4+ small/medium T-cell lymphoma (PCSM-TCL) or primary cutaneous marginal zone lymphoma (PCMZL), respectively. However, in recent years there is growing awareness that neither these immunohistochemical criteria nor demonstration of T-cell or B-cell clonality is specific for malignant lymphomas. In addition, many studies have reported that these low-grade malignant CTCL and CBCL have an indolent clinical behavior and an excellent prognosis with disease-specific survival rates of or close to 100%. As a result, recent classifications have downgraded several low-grade malignant cutaneous lymphomas to lymphoproliferative disorder (LPD). Both the 5th edition of the WHO classification (2022) and the 2022 International Consensus Classification (ICC) of mature lymphoid neoplasms reclassified PCSM-TCL as primary cutaneous CD4+ small/medium T-cell LPD and primary cutaneous acral CD8+ T-cell lymphoma as primary cutaneous acral CD8+ T cell LPD. While the 2022 ICC introduced the term "primary cutaneous marginal zone LPD," in the 5th edition of the WHO classification PCMZL is maintained. In this review we describe the background and rationale of the continually changing terminology of these conditions and discuss the clinical consequences of downgrading malignant lymphomas to LPDs.

Interstitial mycosis fungoides: A rare presentation of mycosis fungoides with overlapping granulomatous and folliculotropic features.

Interstitial mycosis fungoides (IMF) is a rare subtype of mycosis fungoides (MF) characterized by atypical lymphocytes infiltrating the reticular dermis between collagen bundles with limited epidermotropism and variable granulomatous features. Retrospective single institution review of 31 cases of IMF including clinical characteristics, disease course and pathological features. Our cohort was predominately male (19; 61%, M:F 1.6:1) with a mean age at diagnosis of 43 years (range 11-85), mean signs/symptoms duration of 7 years prior to diagnosis, and 6 years mean follow-up duration. Clinically, patients often exhibited symmetric ill-defined patches/plaques involving intertriginous regions with tan-yellow hyperpigmentation and follicular-based papules, wrinkling, and alopecia. Lymphadenopathy was noted in seven patients. Fifteen (52%) patients were in near or complete clinical remission at the latest follow-up. T-cell receptor gene rearrangement was positive in 23/24 (96%) cases. Histopathologically, atypical cells were small-medium, CD4+ (29; 94%) or rarely CD4+/CD8+ (1; 3%) lymphocytes infiltrating the reticular dermis with thickened collagen bundles (27; 87%), multinucleated giant cells (12; 39%), and often tracing along adnexa with subtle folliculotropism (12/20; 60%). Our study demonstrates IMF is an indolent subtype of MF with distinct features, including frequent granulomatous and subtle follicular involvement resulting in alopecia.