Rapid, multifluorescent TCRG Vgamma and Jgamma typing: application to T cell acute lymphoblastic leukemia and to the detection of minor clonal populations

Diagnostic utility of the lymphoid screening tube supplemented with TRBC1 for the assessment of T-cell clonality

INTRODUCTION

Flow cytometric panels for the investigation of lymphoproliferative disorders, such as the EuroFlow Lymphoid Screening Tube (LST), often fail to demonstrate T-cell clonality, as a suitable clonality marker was unavailable until recently. Aim of this study was to evaluate the added value of supplementing TRBC1, a flow cytometric T-cell clonality marker, to the LST.

METHODS

Flow cytometric analysis was performed on 830 routine samples referred to our lab for suspicion of hematological malignancy. T-cells with monotypic TRBC1-expression were additionally characterized with a 12-color T-cell tube and molecular T-cell receptor gamma gene rearrangement (TRG).

RESULTS

LST analysis revealed 97 (11.7%) samples with the presence of a monotypic T-cell population according to TRBC1, including 21 (2.5%) "high-count" (≥500 cells/μL blood or ≥15% of lymphocytes) and 76 (9.2%) "low-count" (<500 cells/μL blood or <15% of lymphocytes) populations. Clinical symptoms indicative for T-CLPD could be correlated to 11/21 "high-count" and 17/76 "low-count" monotypic T-cell populations. Molecular TRG analysis demonstrated a monoclonal result in 76% (16/21) of "high-count" samples and in 64% (42/66; 10 samples not tested) of "low-count" samples, but also in 9/20 samples with polytypic TRBC1 results.

CONCLUSION

Analysis of an LST tube supplemented with TRBC1 led to the detection of a high number of monotypic T-cell populations. The detection of numerous small monotypic T-cell populations raises the question of their clinical significance. A possible flowchart for assessment of these populations, based on the available literature, is proposed. Molecular TRG analysis is complementary and cannot be omitted from T-cell clonality assessment.

Evaluation of next-generation sequencing-based clonality analysis of T-cell receptor gamma gene rearrangements based on a new interpretation algorithm

INTRODUCTION

T-cell receptor gene (TRG) rearrangement profiling is an essential component of the workup at diagnosis of T-cell malignancies. TRG amplification by polymerase chain reaction (PCR) and analysis by capillary electrophoresis (PCR-CE) is mostly widely used but is hampered by a subjective interpretation of its results and possible false-positive interpretation of clonality. Several studies evaluated the advantage of TRG rearrangement analysis by Next Generation Sequencing (TRG-NGS), however few have proposed an adequate data interpretation algorithm.

METHODS

Eighty five fresh and 36 formalin-fixed paraffin embedded (FFPE) diagnostic samples suspected for a lymphoproliferative disorder were analyzed by PCR-CE and TRG NGS. Final clinical diagnosis was available for all fresh samples. Reproducibility, analytical specificity and sensitivity of the TRG NGS analysis was evaluated.

RESULTS

We propose a new interpretation algorithm for TRG NGS data analysis. PCR-CE and TRG NGS showed identical results in 66/85 (78%) of fresh samples. Sensitivities to detect T-cell malignancies were comparable (96% versus 92%, respectively). The analysis of FFPE material was significantly more successful by TRG NGS (34/36 cases) in respect to PCR-CE (16/36 cases), most likely due to the small size of the amplicons.

CONCLUSION

Assessment of T-cell clonality by TRG NGS has a significant added value in the diagnosis of T-cell disorders as an adjunct to PCR-CE, particularly in difficult to interpret cases or when analyzing FFPE samples.

A Single-Tube, EuroClonality-Inspired, TRG Clonality Multiplex PCR Aids Management of Patients with Enteropathic Diseases, including from Formaldehyde-Fixed, Paraffin-Embedded Tissues

Celiac disease is a chronic inflammation of the small intestine with villous atrophy that can become refractory to a gluten-free diet. Two categories of refractory celiac disease can be distinguished by the phenotype of intraepithelial lymphocytes and the status of TRG genes. Their distinction is important because 30% to 50% of type II but only 0% to 14% of type I evolve to an aggressive enteropathy-associated T-cell lymphoma and therefore require intensive treatment. Currently, differential diagnosis integrates immunohistochemistry, immunophenotyping, and TRG clonality analyses, but each has limitations. A single-tube multiplex TRG PCR (ECN) was prospectively compared to an in-house two-tube TRG PCR (N2T) in 73 samples, including 67 cryopreserved intestine tissues. Thirteen formalin-fixed, paraffin-embedded (FFPE) samples were also analyzed retrospectively. The ECN PCR had comparable efficiency to detect major clonal rearrangements in highly infiltrated tissues from T-cell lymphoproliferative disorders and type II refractory celiac disease and to detect the persistence of minor clones in type II refractory celiac disease follow-up samples. The ECN PCR abolished the risk of amplification of false-positive weak clonal rearrangements in cryopreserved specimens and allowed improved detection of clonal rearrangements in DNA from FFPE samples. The ECN PCR allows robust assessment of cryopreserved and FFPE digestive tissues at diagnosis and follow-up of enteropathies with villous atrophy, thus guiding therapeutic management.

Anaplastic large cell lymphoma arises in thymocytes and requires transient TCR expression for thymic egress

Anaplastic large cell lymphoma (ALCL) is a peripheral T-cell lymphoma presenting mostly in children and young adults. The natural progression of this disease is largely unknown as is the identity of its true cell of origin. Here we present a model of peripheral ALCL pathogenesis where the malignancy is initiated in early thymocytes, before T-cell receptor (TCR) β-rearrangement, which is bypassed in CD4/NPM–ALK transgenic mice following Notch1 expression. However, we find that a TCR is required for thymic egress and development of peripheral murine tumours, yet this TCR must be downregulated for T-cell lymphomagenesis. In keeping with this, clonal TCR rearrangements in human ALCL are predominantly in-frame, but often aberrant, with clonal TCRα but no comparable clonal TCRβ rearrangement, yielding events that would not normally be permissive for survival during thymic development. Children affected by ALCL may thus harbour thymic lymphoma-initiating cells capable of seeding relapse after chemotherapy.

Anaplastic large cell lymphoma is characterized by an NPM–ALK fusion but the cell of origin for this cancer is unclear. Here, the authors show that, in an NPM–ALK mouse model, the tumours likely arise from early thmyocytes and require an initial burst of TCR signalling for initiation.

Accurate detection of the tumor clone in peripheral T-cell lymphoma biopsies by flow cytometric analysis of TCR-Vβ repertoire

Multiparametric flow cytometry has proven to be a powerful method for detection and immunophenotypic characterization of clonal subsets, particularly in lymphoproliferative disorders of the B-cell lineage. Although in theory promising, this approach has not been comparably fulfilled in mature T-cell malignancies. Specifically, the T-cell receptor-Vβ repertoire analysis in blood can provide strong evidence of clonality, particularly when a single expanded Vß family is detected. The purpose of this study was to determine the relevance of this approach when applied to biopsies, at the site of tumor involvement. To this end, 30 peripheral T-cell lymphoma and 94 control biopsies were prospectively studied. Vβ expansions were commonly detected within CD4+ or CD8+ T cells (97% of peripheral T-cell lymphoma and 54% of non-peripheral T-cell lymphoma cases); thus, not differentiating malignant from reactive processes. Interestingly, we demonstrated that using a standardized evaluation, the detection of a high Vβ expansion was closely associated with diagnosis of peripheral T-cell lymphoma, with remarkable specificity (98%) and sensitivity (90%). This approach also identified eight cases of peripheral T-cell lymphoma that were not detectable by other forms of immunophenotyping. Moreover, focusing Vβ expression analysis to T-cell subsets with aberrant immunophenotypes, we demonstrated that the T-cell clone might be heterogeneous with regard to surface CD7 or CD10 expression (4/11 cases), providing indication on 'phenotypic plasticity'. Finally, among the wide variety of Vβ families, the occurrence of a Vβ17 expansion in five cases was striking. To our knowledge, this is the first report demonstrating the power of T-cell receptor-Vβ repertoire analysis by flow cytometry in biopsies as a basis for peripheral T-cell lymphoma diagnosis and precise T-cell clone identification and characterization.

Role of minimal residual disease monitoring in adult and pediatric acute lymphoblastic leukemia

Assays that measure minimal residual disease (MRD) can determine the response to treatment in patients with acute lymphoblastic leukemia (ALL) much more precisely than morphologic screening of bone marrow smears. The clinical significance of MRD, detected by flow cytometry or polymerase chain reaction-based methods in childhood ALL, has been established. Hence, MRD is being used in several clinical trials to adjust treatment intensity. Similar findings have been gathered in adult patients with ALL, making MRD one of the most powerful and informative parameters to guide clinical management. This article discusses practical issues related to MRD methodologies and the evidence supporting the use of MRD for risk assignment in clinical trials.

Normal and pathological V(D)J recombination: contribution to the understanding of human lymphoid malignancies

The majority of haematological cancers involve the lymphoid system. They include acute lymphoblastic leukemias (ALL), which are arrested at variable stages of development and present with blood and bone marrow involvement and chronic leukemias, lymphomas and myelomas, which present with infiltration of a large variety of hematopoietic and non hematopoietic tissues by mature lymphoid cells which express a surface antigen receptor. The majority involve the B-cell lineage and the vast majority have undergone clonal rearrangement of their Ig and/or TCR rearrangements. Analysis of Ig/TCR genomic V(D)J repertoires by PCR based lymphoid clonality analysis within a diagnostic setting allows distinction of clonal from reactive lymphoproliferative disorders, clonal tracking for evidence of tumor dissemination and follow-up, identification of a lymphoid origin in undiagnosed tumors and evaluation of clonal evolution. Ig/TCR VDJ errors are also at the origin of recombinase mediated deregulated expression of a variety of proto-oncogenes in ALL, whereas in lymphoma it is increasingly clear that IgH containing translocations result from abnormalities other than VDJ errors (somatic hypermutation and/or isotype switching). In addition to this mechanistic contribution to lymphoid oncogenesis, it is possible that failure to successfully complete expression of an appropriate Ig or TCR may lead to maturation arrest in a lymphoid precursor, which may in itself contribute to altered tissue homeostasis, particularly if the arrest occurs at a stage of cellular expansion.

Primary leptomeningeal ALK+ lymphoma in a 13-year-old child

A distinct pathologic entity characterized by expression of the anaplastic lymphoma kinase (ALK) protein (hence described as ALK lymphoma) has emerged within the heterogeneous group of CD30 anaplastic large-cell lymphomas. Central nervous system (CNS) involvement is extremely rare in anaplastic large-cell lymphoma. In children, only isolated cases have been reported, mainly as secondary CNS involvement. We report on a 13-year-old boy presenting with headaches and diplopia. Cerebrospinal fluid was infiltrated with atypical large granular lymphocytes. Magnetic resonance imaging of the brain revealed leptomeningeal enhancement. A frontal lobe biopsy showed a pleomorphic neoplasm diffusely infiltrating the meninges composed of large cells with bizarre nuclei similar to those evidenced in cerebrospinal fluid. Immunohistochemical stains showed diffuse strong positivity for CD8, CD30, anaplastic lymphoma kinase protein: p80 and negative monocyte-macrophage and B cell markers. TCR gamma was clonally rearranged. This finding was confirmed by reverse transcription-polymerase chain reaction analysis of the NPM/ALK fusion protein. Epstein-Barr virus was not detected. No evidence of extra-CNS disease was found by imaging study, cytologic examination, or molecular studies. The patient underwent complete remission with polychemotherapy followed by a CNS irradiation. At +10 months from onset, he suffered a full relapse. After a short-term remission with vinblastine, he underwent nonmyeloablative allogeneic bone marrow transplantation, but unfortunately died from multiple organ failure. This case is the first reported occurrence of a primary meningeal ALK lymphoma in a child.

Expansion of regulatory T cells in patients with Langerhans cell histiocytosis

BACKGROUND

Langerhans cell histiocytosis (LCH) is a rare clonal granulomatous disease that affects mainly children. LCH can involve various tissues such as bone, skin, lung, bone marrow, lymph nodes, and the central nervous system, and is frequently responsible for functional sequelae. The pathophysiology of LCH is unclear, but the uncontrolled proliferation of Langerhans cells (LCs) is believed to be the primary event in the formation of granulomas. The present study was designed to further investigate the nature of proliferating cells and the immune mechanisms involved in the LCH granulomas.

METHODS AND FINDINGS

Biopsies (n = 24) and/or blood samples (n = 25) from 40 patients aged 0.25 to 13 y (mean 7.8 y), were studied to identify cells that proliferate in blood and granulomas. We found that the proliferating index of LCs was low ( approximately 1.9%), and we did not observe expansion of a monocyte or dendritic cell compartment in patients. We found that LCH lesions were a site of active inflammation, tissue remodeling, and neo-angiogenesis, and the majority of proliferating cells were endothelial cells, fibroblasts, and polyclonal T lymphocytes. Within granulomas, interleukin 10 was abundant, LCs expressed the TNF receptor family member RANK, and CD4(+) CD25(high) FoxP3(high) regulatory T cells (T-regs) represented 20% of T cells, and were found in close contact with LCs. FoxP3(+) T-regs were also expanded compared to controls, in the blood of LCH patients with active disease, among whom seven out of seven tested exhibited an impaired skin delayed-type hypersensitivity response. In contrast, the number of blood T-regs were normal after remission of LCH.

CONCLUSIONS

These findings indicate that LC accumulation in LCH results from survival rather than uncontrolled proliferation, and is associated with the expansion of T-regs. These data suggest that LCs may be involved in the expansion of T-regs in vivo, resulting in the failure of the host immune system to eliminate LCH cells. Thus T-regs could be a therapeutic target in LCH.

Powerful strategy for polymerase chain reaction-based clonality assessment in T-cell malignancies Report of the BIOMED-2 Concerted Action BHM4 CT98-3936

Polymerase chain reaction (PCR) assessment of clonal T-cell receptor (TCR) and immunoglobulin (Ig) gene rearrangements is an important diagnostic tool in mature T-cell neoplasms. However, lack of standardized primers and PCR protocols has hampered comparability of data in previous clonality studies. To obtain reference values for Ig/TCR rearrangement patterns, 19 European laboratories investigated 188 T-cell malignancies belonging to five World Health Organization-defined entities. The TCR/Ig spectrum of each sample was analyzed in duplicate in two different laboratories using the standardized BIOMED-2 PCR multiplex tubes accompanied by international pathology panel review. TCR clonality was detected in 99% (143/145) of all definite cases of T-cell prolymphocytic leukemia, T-cell large granular lymphocytic leukemia, peripheral T-cell lymphoma (unspecified) and angioimmunoblastic T-cell lymphoma (AILT), whereas nine of 43 anaplastic large cell lymphomas did not show clonal TCR rearrangements. Combined use of TCRB and TCRG genes revealed two or more clonal signals in 95% of all TCR clonal cases. Ig clonality was mostly restricted to AILT. Our study indicates that the BIOMED-2 multiplex PCR tubes provide a powerful strategy for clonality assessment in T-cell malignancies assisting the firm diagnosis of T-cell neoplasms. The detected TCR gene rearrangements can also be used as PCR targets for monitoring of minimal residual disease.

Minimal Disease Detection and Confirmation in Hematologic Malignancies: Combining Cell Sorting with Clonality Profiling

Background: In this study we demonstrate the technical application of flow cytometry and cell sorting combined with gene-rearrangement clonality profiling to detect and confirm minimal disease in 2 leukemia and 2 lymphoma cases.

Methods: Specimens with low percentages (0.05%–5%) of abnormal lymphoid populations were identified by flow cytometry. The abnormal lymphoid populations were sorted by flow cytometry, and the purified tumor populations along with unsorted fractions were subsequently analyzed for the presence of clonal gene rearrangements by PCR and fluorescence-based capillary electrophoresis fragment analysis.

Results: In 3 cases, distinct clonality profiles could be detected in the purified tumor cell fraction, and suspicious amplicons of identical sizes were detected among the polyclonal backgrounds in the unsorted specimens. For 1 patient, a monoclonal signal was detected in the sorted tumor cell fraction but not in the unseparated bone marrow specimen containing 0.05% abnormal lymphoblasts. A subsequent bone marrow specimen containing 4.8% recurring leukemia cells tested positive with a clonality profile that matched the previous profile in the sorted cell population.

Conclusions: The described method integrating 2 technologies allows genotypic confirmation of an aberrant population detected by immunophenotype to increase diagnostic certainty. This strategy provides a sensitive tool for disease monitoring without the need for patient-specific primer design and assay optimization required for quantitative PCR analysis.

Monitoring of minimal residual disease in acute myeloid leukemia

Monitoring minimal residual disease (MRD) becomes increasingly important in the risk-adapted management of patients with acute myeloid leukemia (AML). The two most sensitive and quantitative methods for MRD detection are multiparameter flow cytometry (MFC) and real-time polymerase chain reaction (QRT-PCR). Fusion gene-specific PCR in AML is based on the RNA level, and thus in contrast to MFC expression levels rather than cell counts are assessed. For both methods independent prognostic values have been shown. The strong power of MFC has been shown mainly in the assessment of early clearance of the malignant clone. MRD levels in AML with fusion genes have the strongest prognostic power after the end of consolidation therapy. In addition, with QRT-PCR highly predictive initial expression levels can be assessed. With both methods early detection of relapse is possible. So far, validated PCR-based MRD was done with fusion genes that are detectable in only 20-25% of all AML MFC is superior since it is applicable for most AML. However, QRT-PCR is still more sensitive in most cases. Thus, it is desirable to establish new molecular markers for PCR-based studies. Large clinical trials will determine the role and place of immunologic and PCR-based monitoring in the prognostic stratification of patients with AML.

Impaired genomic stability and increased oxidative stress exacerbate different features of Ataxia-telangiectasia

Ataxia-telangiectasia (A-T) is a multisystem, cancer-predisposing genetic disorder caused by deficiency of the ATM protein. To dissect the A-T phenotype, we augmented specific features of the human disease by generating mouse strains that combine Atm deficiency with dysfunction of other proteins. Increasing oxidative stress by combining deficiencies in Atm and superoxide dismutase 1 (Sod1) exacerbated growth retardation and markedly reduced the mean survival time following ionizing radiation. In contrast, increasing genomic instability by combining deficiencies of Atm and the mismatch repair protein Mlh1 caused a moderate increase in radiation sensitivity and dramatic increase in aggressive lymphomas, compared with thes Atm-/- single knockout. Remarkably, Atm, Mlh1 or Mlh1/Atm single or double heterozygosity did not significantly affect the life span of the various genotypes. Mlh1/Atm double null tumors were polyclonal, whereas the tumors in other genotypes were mono- or oligoclonal, demonstrating the high predisposition of thymocytes with this genotype to become malignant. Chromosomal aberrations in the tumors were localized mainly in chromosomes 12 and 15. The genomic region on chromosome 15, which contains the gene for the c-Myc oncoprotein, was commonly amplified, and elevated levels of the c-Myc protein were subsequently observed in the tumors. Our data suggest that impaired genomic instability is an important contributing factor to cancer predisposition in A-T, whereas oxidative stress is more important in the radiation sensitivity and growth retardation facets of this disease.

Mono/oligoclonal pattern of Kaposi Sarcoma-associated herpesvirus (KSHV/HHV-8) episomes in primary effusion lymphoma cells

Primary effusion lymphoma (PEL) is a rare lymphoma of B-cell origin, developed in serous cavities. PEL tumor cells are latently infected with Kaposi sarcoma-associated herpesvirus (KSHV) and in most cases co-infected with Epstein-Barr virus (EBV). In 15 primary PEL tumors including 10 EBV-positive cases, we analyzed the fused terminal repeat (TR) regions of KSHV episomes using pulsed-field gel electrophoresis and Southern blot. On the same genomic DNA samples, the cellular clonality was assessed by Southern blot and PCR detection of monoclonal immunoglobulin heavy chain (IGH) VDJ gene rearrangements, associated in the EBV-infected cases, with Southern blot analysis of the fused termini of EBV episomes. Monoclonal IGH gene rearrangements were detected in 13 tumors using Southern blot, in 11 cases using PCR, and in all cases considering both methods. EBV infection was monoclonal in all EBV-positive cases. However, only 5 PEL tumors were found to be monoclonally infected with KSHV. In the 10 other cases, we found a biclonal (2 bands; n = 4) or an oligoclonal pattern (3-6 bands; n = 6) of KSHV episomes. We hypothesized that the apparent discrepancy between viral and cellular clonalities in PEL might be due to several phenomena including complex mechanisms of genomic recircularization, insertion of duplicated sequences into the TR region and simultaneous infection of tumor cells with defective KSHV variants. KSHV infection of contaminating nontumoral cells, superinfection from lytically infected cells or viral integration events might also explain the oligoclonal pattern of KSHV infection. Several of these mechanisms, not mutually exclusive, might coexist in a single tumor.

Philadelphia-chromosome-positive T-lymphoblastic leukemia: acute leukemia or chronic myelogenous leukemia blastic crisis

The Ph1 chromosome has rarely been reported in T-lineage acute lymphoblastic leukemia (T-ALL), and the clinical relevance of this translocation in T-ALL is currently unknown. In chronic myelogenous leukemia (CML) some data indicate derivation of T-cells from the leukemic clone and only a few cases of T-derived blastic crisis have been reported and quite often disputed. Particularly in cases identified initially in blastic crisis it may be difficult to distinguish those from Ph1-positive T-ALL. We herein report 2 patients who presented with a clinical picture of Ph1-positive T-ALL and who raised a differential diagnosis from T-cell blastic crisis of CML. We review the literature and suggest clinical and laboratory features that can help in the diagnosis. According to our literature review, 23 cases of Ph1-positive T-ALL and 44 cases of T-cell blastic crisis of CML, including ours, were reported. Some major differences between the two entities could help in establishing a diagnosis of Ph1-positive T-cell blastic crisis of CML vs. Ph1-positive T-ALL: Male sex and younger age was more predominant in T-ALL. While in most cases of CML blastic crisis there was a history of CML there was no such history in the T-ALL cases. Medullary involvement with lymphoblastic leukemia was present in all cases of T-ALL but only in about half of the cases of CML blastic crisis. None of the CML-blastic crisis cases tested by RT-PCR showed the minor breakpoint transcript, while 2 cases with T-ALL had the minor breakpoint transcript and 1 had both transcripts. Combined morphologic and FISH analysis can help to distinguish between the two entities and was applied in one of our cases. Although both entities carry a severe prognosis, differentiating between them might have clinical relevance, especially in the imatinib era.

Response to antiviral treatment in hepatitis C virus-associated marginal zone lymphomas

A link between chronic hepatitis C virus (HCV) infection and low-grade B-cell lymphomas has been suggested by epidemiological studies. Marginal zone lymphomas (MZLs) including splenic lymphomas with villous lymphocytes are among the most frequently reported subgroups in the setting of chronic HCV infection. In this study, we examined the effect of antiviral treatment in eight patients with HCV-associated MZL. We found that five out of eight patients have responded to interferon alpha and ribavirin. In some cases, hematologic responses were correlated to virologic responses. In addition, we report a case of large granular lymphocyte leukemia occurring in association with MZL and HCV, and responding to interferon and ribavirin. We suggest that there is an etiologic link between HCV and antigen-driven lymphoproliferative disorders.

The role of molecular studies in lymphoma diagnosis: a review

Lymphoma classification is based on a multiparametric approach to diagnosis, in which clinical features, morphology, immunophenotype, karyotype and molecular characteristics are important to varying degrees. While in most cases, a diagnosis can be confidently established on the basis of morphology and immunophenotype alone, a small proportion of diagnostically difficult cases will rely on molecular studies to enable a definitive diagnosis. This review discusses the various molecular techniques available including Southern blotting (SB), polymerase chain reaction (PCR), fluorescence in situ hybridisation (FISH)--including multicolour-FISH/spectral karyotyping and comparative genomic hybridisation--and also gene expression profiling using cDNA microarray technology. Emphasis is given to the analysis of antigen receptor gene rearrangements and chromosomal translocations as they relate to lymphoma diagnosis and also in the setting of minimal residual disease (MRD) detection and monitoring. Laboratories performing these tests need to have expertise in these areas of testing, and there is a need for greater standardisation of molecular tests. It is important to know the sensitivity and specificity of each test as well as its limitations and the pitfalls in the interpretation of results. Above all, results of molecular testing should never be considered in isolation, and must always be interpreted in the context of clinical and other laboratory data.

Clinicobiological, immunophenotypic, and molecular characteristics of monoclonal CD56-/+dim chronic natural killer cell large granular lymphocytosis

Indolent natural killer (NK) cell lymphoproliferative disorders include a heterogeneous group of patients in whom persistent expansions of mature, typically CD56(+), NK cells in the absence of any clonal marker are present in the peripheral blood. In the present study we report on the clinical, hematological, immunophenotypic, serological, and molecular features of a series of 26 patients with chronic large granular NK cell lymphocytosis, whose NK cells were either CD56(-) or expressed very low levels of CD56 (CD56(-/+dim) NK cells), in the context of an aberrant activation-related mature phenotype and proved to be monoclonal using the human androgen receptor gene polymerase chain reaction-based assay. As normal CD56(+) NK cells, CD56(-/+dim) NK cells were granzyme B(+), CD3(-), TCRalphabeta/gammadelta(-), CD5(-), CD28(-), CD11a(+bright), CD45RA(+bright), CD122(+), and CD25(-) and they showed variable and heterogeneous expression of both CD8 and CD57. Nevertheless, they displayed several unusual immunophenotypic features. Accordingly, besides being CD56(-/+dim), they were CD11b(-/+dim) (heterogeneous), CD7(-/+dim) (heterogeneous), CD2(+) (homogeneous), CD11c(+bright) (homogeneous), and CD38(-/+dim) (heterogeneous). Moreover, CD56(-/+dim) NK cells heterogeneously expressed HLA-DR. In that concerning the expression of killer receptors, CD56(-/+dim) NK cells showed bright and homogeneous CD94 expression, and dim and heterogeneous reactivity for CD161, whereas CD158a and NKB1 expression was variable. From the functional point of view, CD56(-/+dim) showed a typical Th1 pattern of cytokine production (interferon-gamma(+), tumor necrosis factor-alpha(+)). From the clinical point of view, these patients usually had an indolent clinical course, progression into a massive lymphocytosis with lung infiltration leading to death being observed in only one case. Despite this, they frequently had associated cytopenias as well as neoplastic diseases and/or viral infections. In summary, we describe a unique and homogeneous group of monoclonal chronic large granular NK cell lymphocytosis with an aberrant activation-related CD56(-/+dim)/CD11b(-/+dim) phenotype and an indolent clinical course, whose main clinical features are related to concomitant diseases.

Age-related phenotypic and oncogenic differences in T-cell acute lymphoblastic leukemias may reflect thymic atrophy

Postnatal thymic involution occurs progressively throughout the first 3 decades of life. It predominantly affects T-cell receptor (TCR) alphabeta-lineage precursors, with a consequent proportional increase in multipotent thymic precursors. We show that T-acute lymphoblastic leukemias (T-ALLs) demonstrate a similar shift with age from predominantly TCR expressing to an immature (IM0/delta/gamma) stage of maturation arrest. Half demonstrate HOX11, HOX11L2, SIL-TAL1, or CALM-AF10 deregulation, with each being associated with a specific, age-independent stage of maturation arrest. HOX11 and SIL-TAL represent alphabeta-lineage oncogenes, whereas HOX11L2 expression identifies an intermediate alphabeta/gammadelta-lineage stage of maturation arrest. In keeping with preferential alphabeta-lineage involution, the incidence of SIL-TAL1 and HOX11L2 deregulation decreased with age. In contrast, HOX11 deregulation became more frequent, suggesting longer latency. TAL1/LMO1 deregulation is more frequent in alphabeta-lineage T-ALL, when it is predominantly due to SIL-TAL1 rearrangements in children but to currently unknown mechanisms in adolescents and adults. LMO2 was more frequently coexpressed with LYL1, predominantly in IM0/delta/gamma adult cases, than with TAL1. These age-related changes in phenotype and oncogenic pathways probably reflect progressive changes in the thymic population at risk of malignant transformation.

Design and standardization of PCR primers and protocols for detection of clonal immunoglobulin and T-cell receptor gene recombinations in suspect lymphoproliferations: report of the BIOMED-2 Concerted Action BMH4-CT98-3936

In a European BIOMED-2 collaborative study, multiplex PCR assays have successfully been developed and standardized for the detection of clonally rearranged immunoglobulin (Ig) and T-cell receptor (TCR) genes and the chromosome aberrations t(11;14) and t(14;18). This has resulted in 107 different primers in only 18 multiplex PCR tubes: three VH-JH, two DH-JH, two Ig kappa (IGK), one Ig lambda (IGL), three TCR beta (TCRB), two TCR gamma (TCRG), one TCR delta (TCRD), three BCL1-Ig heavy chain (IGH), and one BCL2-IGH. The PCR products of Ig/TCR genes can be analyzed for clonality assessment by heteroduplex analysis or GeneScanning. The detection rate of clonal rearrangements using the BIOMED-2 primer sets is unprecedentedly high. This is mainly based on the complementarity of the various BIOMED-2 tubes. In particular, combined application of IGH (VH-JH and DH-JH) and IGK tubes can detect virtually all clonal B-cell proliferations, even in B-cell malignancies with high levels of somatic mutations. The contribution of IGL gene rearrangements seems limited. Combined usage of the TCRB and TCRG tubes detects virtually all clonal T-cell populations, whereas the TCRD tube has added value in case of TCRgammadelta(+) T-cell proliferations. The BIOMED-2 multiplex tubes can now be used for diagnostic clonality studies as well as for the identification of PCR targets suitable for the detection of minimal residual disease.

[Application of molecular biology techniques to malignant haematology]

Malignant hemopathies, although heterogeneous in their prognosis and oncogenesis, represent an interesting model for studying cancer genesis mechanisms in man through the recurrent presence of genetic abnormalities involved in oncogenesis and the availability of tumour material. Nowadays, molecular biology techniques are very much used for the diagnosis, the treatment and the follow-up of these diseases. Firstly used for research, the new techniques have completely changed our ability to characterise malignant hemopathies and to understand the cancer-inducing processes, permitting us to perform the biological assessment of patients with malignant hemopathies, the diagnosis, and to estimate and follow the outcome of patients after treatment. At a more fundamental level, the structural and functional analysis of the deregulated genes implied in leukaemia and lymphoma has improved our knowledge and understanding of oncogenic and physiologic mechanisms significantly.

Clonality profile in relapsed precursor-B-ALL children by GeneScan and sequencing analyses. Consequences on minimal residual disease monitoring

Detection of minimal residual disease (MRD), using immunoglobulin (Ig) and T-cell receptor (TCR) gene rearrangements as clone-specific targets, represents the most recent development in diagnosis and treatment of acute lymphoblastic leukaemia (ALL). Nevertheless, risk of false-negative results, due to secondary or ongoing rearrangements of Ig/TCR genes during the disease course, might hamper MRD detection. Therefore, to gain extensive information on clonal stability, we performed PCR-GeneScan analysis of Ig/TCR gene rearrangements at diagnosis and subsequent relapse in bone marrow samples from 53 childhood precursor-B-ALL patients. In addition, sequencing analysis of junctional regions at diagnosis and relapse provided a detailed insight in the stability and changes of Ig/TCR gene rearrangements during the disease course. At least one stable clonal Ig/TCR target was found in 94% of patients. In three patients complete differences in Ig/TCR rearrangements between diagnosis and relapse were observed, suggesting relapse with a new clone. At relapse, 71% of diagnostic clonal PCR targets was conserved. Since the comparison of Ig/TCR gene rearrangements at diagnosis and relapse in our precursor-B-ALL patients did not show significant difference in the stability of different clonal PCR targets (IGH, 70%; IGK, 71%; TCRD, 67%; TCRG, 75%), we conclude that there is no 'preferential' clone-specific target for MRD monitoring.

PCR detection of clonal IgH and TCR gene rearrangements at the end of induction as a non-remission criterion in children with ALL: comparison with standard morphologic analysis and risk group classification

BACKGROUND

The initial response to induction therapy is currently considered one of the most important prognostic factors in acute lymphoblastic leukemias (ALL). A series of methods for the detection of submicroscopic levels of residual disease in patients with ALL mainly based on PCR and immunophenotyping has been developed, demonstrating that the presence of high levels of residual disease at the end of induction therapy is an important, independent prognostic factor. We determined the usefulness of PCR detection of minimal residual disease using consensus primers as a non-remission criterion.

PROCEDURE

Bone marrow samples obtained from 49 children with ALL were analyzed at diagnosis and at the end of induction therapy for the detection of clonal IgH, TCRdelta, and TCRgamma rearrangements by PCR. The results were compared with those obtained by standard morphologic analysis and risk group classification.

RESULTS

Patients who had clonality detected at the end of induction showed a significantly higher recurrence rate and lower event-free survival than those without detected clonality (24.9% vs. 89.7%) (P < 0.0001). Multivariate analysis revealed that detection of clonality at the end of induction was the most important, independent prognostic factor when associated with age, number of white blood cells, and immunophenotyping.

CONCLUSIONS

PCR detection of clonality using consensus primers is a relatively simple technique that is able to identify patients with a high chance of recurrence, and shows a higher sensitivity and a better prognostic value than standard morphologic analysis and risk group classification, defining a new remission criterion. However, further multicentric prospective studies using this technique employing a larger number of cases are necessary to confirm these findings.

Recurrent partial trisomy 1q22-q44 in clonal intraepithelial lymphocytes in refractory celiac sprue

BACKGROUND & AIMS

Refractory celiac sprue, a low-grade intraepithelial lymphoma characterized by expansion of clonal intraepithelial lymphocytes with intracellular CD3 epsilon but no surface CD3-T-cell receptor complexes, can be an intermediary step between celiac disease and overt T-cell lymphoma. To gain insight into the mechanisms of lymphomagenesis in celiac disease, we have performed the first cytogenetic study in refractory celiac sprue.

METHODS

Karyotypes were performed on: (1) 7 cell lines derived from clonal intraepithelial lymphocytes of patients with refractory celiac sprue; (2) 14 control T-cell lines, either from 4 of 7 patients with refractory celiac sprue or from 10 patients with uncomplicated celiac disease; and (3) bone marrow and peripheral blood lymphocytes in 1 of 7 patients with refractory celiac sprue. Rearrangements were confirmed by in situ hybridization using whole-chromosome painting probes and by comparative genomic hybridization in one patient.

RESULTS

A recurrent structural chromosomal aberration leading to partial trisomy of the long arm of chromosome 1 was found in 6 of 7 cell lines from patients with refractory celiac sprue but in none of the control T-cell lines. In one patient with circulating abnormal intraepithelial lymphocytes, the partial trisomy 1q was confirmed on cells freshly isolated from bone marrow and blood.

CONCLUSIONS

Refractory celiac sprue is strongly associated with partial trisomy of the 1q region. Gain of chromosome 1q, recently found in 16% of enteropathy-type T-cell lymphoma, may be an early event in lymphomagenesis related to celiac disease and provides a key to investigating molecular mechanisms of lymphoid transformation in this disease.

Detection of minimal residual disease in hematologic malignancies by real-time quantitative PCR: principles, approaches, and laboratory aspects

Detection of minimal residual disease (MRD) has prognostic value in many hematologic malignancies, including acute lymphoblastic leukemia, acute myeloid leukemia, chronic myeloid leukemia, non-Hodgkin's lymphoma, and multiple myeloma. Quantitative MRD data can be obtained with real-time quantitative PCR (RQ-PCR) analysis of immunoglobulin and T-cell receptor gene rearrangements, breakpoint fusion regions of chromosome aberrations, fusion-gene transcripts, aberrant genes, or aberrantly expressed genes, their application being dependent on the type of disease. RQ-PCR analysis can be performed with SYBR Green I, hydrolysis (TaqMan) probes, or hybridization (LightCycler) probes, as detection system in several RQ-PCR instruments. Dependent on the type of MRD-PCR target, different types of oligonucleotides can be used for specific detection, such as an allele-specific oligonucleotide (ASO) probe, an ASO forward primer, an ASO reverse primer, or germline probe and primers. To assess the quantity and quality of the RNA/DNA, one or more control genes must be included. Finally, the interpretation of RQ-PCR MRD data needs standardized criteria and reporting of MRD data needs international uniformity. Several European networks have now been established and common guidelines for data analysis and for reporting of MRD data are being developed. These networks also include standardization of technology as well as regular quality control rounds, both being essential for the introduction of RQ-PCR-based MRD detection in multicenter clinical treatment protocols.

The distribution of gene segments in T-cell receptor gamma gene rearrangements demonstrates the need for multiple primer sets

Limited data exist regarding the distribution of gene segments used in T-cell receptor gamma gene rearrangements (TCR gamma GR) in T-cell lymphoproliferative disorders. The reported efficacy of TCR gamma GR protocols ranges from 60% to greater than 90%. Laboratories reporting a lower detection rate tend to use a limited set of primers. The goal of our study was to provide TCR gamma GR data to demonstrate the molecular biological basis for needing multiple primer sets targeting all gene segments. Sixty cases with a confirmed histological diagnosis of a T-cell lymphoproliferative disorder and TCR gamma GR were identified in our lymphoma registry from 1995 to 2001. DNA was obtained from fresh/frozen tissue, cell lysates, or paraffin-embedded tissue. Variable (V gamma) region gene segments were identified using denaturing gradient gel electrophoresis, which was used to select the cases in the study. Capillary electrophoresis using fluorescent-labeled joining (J gamma) region primers was performed to identify J gamma segments. Sixty cases contained a total of 98 TCR gamma GR, as some cases have more than one rearrangement. The most frequent gene segment combination involved the V gamma 1-8 and J gamma 1/2 segments. If a single primer set directed at these two segments were used for clinical diagnosis, that pair of primers would only diagnose 67% of cases as positive for TCR gamma GR. Our gene segment distribution data emphasize the importance of using a comprehensive set of V gamma and J gamma primers for an optimal detection rate of TCR gamma GR. Protocols with limited numbers of primers should be reconsidered.

Analysis of TCR, pT alpha, and RAG-1 in T-acute lymphoblastic leukemias improves understanding of early human T-lymphoid lineage commitment

T-acute lymphoblastic leukemias (T-ALLs) derive from human T-lymphoid precursors arrested at various early stages of development. Correlation of phenotype and T-cell receptor (TCR) status with RAG-1 and pT alpha transcription in 114 T-ALLs demonstrated that they largely reflect physiologic T-lymphoid development. Half the TCR alpha beta lineage T-ALLs expressed a pre-TCR, as evidenced by RAG-1, pT alpha, and cTCR beta expression, absence of TCR delta deletion, and a sCD3(-), CD1a(+), CD4/8 double-positive (DP) phenotype, in keeping with a population undergoing beta selection. Most TCR gamma delta T-ALLs were pT alpha, terminal deoxynucleotidyl transferase (TdT), and RAG-1(lo/neg), double-negative/single-positive (DN/SP), and demonstrated only TCR beta DJ rearrangement, whereas 40% were pT alpha, TdT, and RAG-1 positive, DP, and demonstrated TCR beta V(D)J rearrangement, with cTCR beta expression in proportion. As such they may correspond to TCR alpha beta lineage precursors selected by TCR gamma delta expression, to early gamma delta cells recently derived from a pT alpha(+) common alpha beta/gamma delta precursor, or to a lineage-deregulated alpha beta/gamma delta intermediate. Approximately 30% of T-ALLs were sCD3/cTCR beta(-) and corresponded to nonrestricted thymic precursors because they expressed non-T-restricted markers such as CD34, CD13, CD33, and CD56 and were predominantly DN, CD1a, pT alpha, and RAG-1 low/negative, despite immature TCR delta and TCR gamma rearrangements. TCR gene configuration identified progressive T-lymphoid restriction. T-ALLs, therefore, provide homogeneous expansions of minor human lymphoid precursor populations that can aid in the understanding of healthy human T-cell development.

IMGT databases, web resources and tools for immunoglobulin and T cell receptor sequence analysis, http://imgt.cines.fr

IMGT, the international ImMunoGeneTics database((R)) (http://imgt.cines.fr), is a high-quality integrated information system specializing in immunoglobulins (IG), T cell receptors (TR) and major histocompatibility complex (MHC) of human and other vertebrates, created in 1989, by LIGM, at the Université Montpellier II, CNRS, Montpellier, France. IMGT provides a common access to standardized data which include nucleotide and protein sequences, oligonucleotide primers, gene maps, genetic polymorphisms, specificities, 2D and 3D structures. IMGT includes several databases (IMGT/LIGM-DB, IMGT/3Dstructure-DB, IMGT/HLA-DB), Web resources ('IMGT Marie-Paule page') and interactive tools (IMGT/V-QUEST, IMGT/JunctionAnalysis). IMGT expertly annotated data and tools described in this paper are particularly useful for the analysis of the IG and TR rearrangements in leukemia, lymphoma and myeloma, and in translocations involving the antigen receptor loci. IMGT is freely available at http://imgt.cines.fr.

Angio-immunoblastic T cell lymphoma (AILD-TL) rich in large B cells and associated with Epstein-Barr virus infection. A different subtype of AILD-TL?

We studied eight patients with characteristic features of angio-immunoblastic T cell lymphoma (AILD-TL) associated with more than 25% of large B cells. Polymerase chain reaction (PCR) analysis showed a clonal rearrangement of the T cell receptor (TCR)-gamma chain gene in all cases. One additional case showed a clonal rearrangement of the TCR-beta chain gene by Southern blot hybridization. PCR analysis showed a clonal immunoglobulin rearrangement in three cases presenting with more than 50% of large B cells whereas the other cases had a germline configuration. In 6/8 cases, double-labeling immunohistochemistry and in situ hybridization demonstrated that Epstein-Barr virus (EBV) was mostly present in the large B cells but also detected in some T cells. We further evaluated the frequency of AILD-TL with more than 25% of large B cells in the 106 cases collected by the French GELA group and found an incidence of 18%. The outcome of these patients did not differ significantly from those with less than 25% of B cells. With this approach we confirm the heterogeneity of AILD-TL features and the possible association with a substantial numbers of CD20(+), EBV(+) large B cells. We propose to denominate these cases as 'AILD-TL rich in large B cells' and to consider them as a different entity which can be misdiagnosed as a reactive process or as T cell rich B cell lymphoma.

Combined analysis of T cell receptor gamma and immunoglobulin heavy chain gene rearrangements at the single-cell level in lymphomas with dual genotype

By prospectively studying immunoglobulin heavy chain gene (IgH) and T cell receptor gamma (TCRgamma) gene rearrangements in 398 lymphoma cases, a dual genotype was observed in 13% of B cell and 11% of T cell lymphomas. According to histological subtype, the highest incidence was observed for mantle cell lymphomas (32%) and lymphoplasmacytic lymphoma (21%) among B cell lymphomas, and for angioimmunoblastic lymphoma (AILT) (46%) and Sézary syndrome (SS) (50%) among T cell lymphomas. To determine whether the dual genotype corresponds to the presence of two distinct monoclonal populations or to the presence of both rearrangements within the same lymphoma cells, single-cell microdissection was used after immunohistochemistry and a single-cell combined IgH and TCRgamma gene analysis was designed after a whole-genome amplification step. This protocol was applied to the study of two nodal B cell lymphomas (one diffuse large B cell lymphoma and one mantle cell lymphoma) and two cutaneous T cell lymphomas (one AILT and one SS). Two cases (SS and mantle cell lymphoma) were true bigenotypic lymphomas, as both IgH and TCRgamma monoclonal rearrangements were detected in the same cells. Conversely, in the diffuse large B cell lymphoma and AILT cases, large CD22+ single cells exhibited only the monoclonal IgH rearrangement but not the TCRgamma gene that was detected in CD3+ single cells. Such an approach allows the identification of true bigenotypic lymphoma among dual genotypic lymphoma. Specific genetic alterations may be further amplified from microdissected cryopreserved material, such as the t(11;14) breakpoint detected in bigenotypic B cells of the mantle cell lymphoma case.

Effectiveness of capillary electrophoresis using fluorescent-labeled primers in detecting T-cell receptor gamma gene rearrangements

We describe the use of fluorescent-labeled primers to analyze T-cell receptor gamma gene rearrangements (TCR gamma GR) using capillary electrophoresis in the ABI Prism 310 Genetic Analyzer. We also compare the performance with denaturing gradient gel electrophoresis (DGGE). In a single multiplex polymerase chain reaction (PCR) we amplified TCR gamma GR with primers for all known groups of variable region genes, and joining region genes described in lymphoid neoplasms. Ten reactive samples, followed by five cell lines and 25 tumor samples with 41 individual TCR gamma GR (due to many biallelic rearrangements) previously identified by DGGE, were analyzed to validate the technique. The capillary electrophoresis protocol has 92% concordance for both TCR clonal status (23 of 25) and 95% concordance in the number of individual TCR gamma GR (38 of 41) identified by DGGE. The reproducible sensitivity for detecting TCR gamma GR diluted in reactive lymphoid DNA is 2% in clinical applications. Discrimination of predominant rearrangements requires a minimum ratio of two times the height of the normal distribution of polyclonal peaks. Capillary electrophoresis can provide results within 60 minutes for each specimen after PCR is complete. Capillary electrophoresis provides a faster result than sequence-based separation methods and gives an archival electronic record. Fluorescent labeling allows the identification of both the variable and joining gene segments used in a TCR gamma GR. The effectiveness of capillary electrophoresis is similar to DGGE.

T cell receptor gamma gene rearrangements as targets for detection of minimal residual disease in acute lymphoblastic leukemia by real-time quantitative PCR analysis

Several studies have shown that quantitative detection of minimal residual disease (MRD) predicts clinical outcome in childhood acute lymphoblastic leukemia (ALL). In this report we investigated the applicablility of T cell receptor gamma (TCRG) gene rearrangements as targets for MRD detection by real-time quantitative PCR analysis. Seventeen children with precursor-B-ALL and 15 children with T-ALL were included in this study. Using an allele-specific (ASO) forward primer in combination with germline Jgamma reverse primers and Jgamma TaqMan probes, a reproducible sensitivity of < or =10(-4) (defined by strict criteria) was obtained in only four out of 19 (21%) TCRG gene rearrangements in precursor-B-ALL patients and in 10 out of 15 (67%) TCRG gene rearrangements in T-ALL patients. The main reason for not obtaining a reproducible sensitivity of < or =10(-4) in approximately 60% of cases was the non-specific amplification of TCRG gene rearrangements in normal T-lymphocytes. A maximal sensitivity of < or =10(-4) (defined by less strict criteria) was obtained in 42% of TCRG gene rearrangements in precursor-B-ALL patients. The number of inserted nucleotides was significantly higher in T-ALL (mean: 8.5) as compared to precursor-B-ALL (mean: 6.8) and appeared to be the most important predictor for reaching a reproducible sensitivity < or =10(-4). The usage of a touchdown PCR or the usage of an ASO reverse primer in combination with Vgamma member forward primers and TaqMan probes did not clearly improve the overall results. Nevertheless, RQ-PCR analysis of TCRG gene rearrangements in follow-up samples obtained from 12 ALL patients showed the applicability of this method for MRD detection. We conclude that RQ-PCR analysis of TCRG gene rearrangements can be used for the detection of MRD, but that sensitivities might be limited due to non-specific amplification. This method is applicable in the majority of T-ALL patients and in almost half of precursor-B-ALL patients, particularly when used as second-choice target for confirmation of the MRD results obtained via the first-choice target.

Molecular analysis of minimal residual disease in adult acute lymphoblastic leukaemia

Despite intensive chemotherapy and stem cell transplantation (SCT) programmes, overall survival in adult acute lymphoblastic leukaemia (ALL) remains poor compared to that in childhood ALL. Despite clinical and morphological remission being achieved by over 80% of patients, 5-year survival is limited to 40% of patients, clearly indicating that morphology is insufficient in predicting future outcome. Molecular assessment of residual disease in bone marrow using immunoglobulin genes as markers of clonality has recently been evaluated in a large adult ALL study in our institution. Analysis of disease-free survival (DFS) rates for minimal residual disease-(MRD-) positive and -negative patients established that MRD positivity was associated with increased relapse rates at all times, being most significant at 3-5 months post-induction and beyond. Pre-autologous SCT tests are predictive of outcome, but for allogeneic SCT outcome is related to results of the tests after the procedure rather than before. The association of MRD test results and DFS was independent of, and greater than, other standard predictors of outcome and is therefore important in determining treatment for individual patients.

Precursor T-cell acute lymphoblastic leukemia in adults: age-related immunophenotypic, cytogenetic, and molecular subsets

We analyzed the clinicopathologic and molecular findings in 26 adults (age 16-72 years) with T-cell acute lymphoblastic leukemia (T-ALL) and observed features that correlated with age. Patients older than 60 years (n = 5) had a low frequency of hepatosplenomegaly (0 [0%]), anterior mediastinal mass (1 [20%]), and lymphadenopathy (2 [40%]), and completely responded to chemotherapy (4 of 4). The T-ALL in this group commonly expressed myeloid antigens (4 [80%]), had lineage-inappropriate gene rearrangements (2/3 [67%]) and chromosome 2 deletion (3/4 [75%]), and exclusively used the V(III) or V(IV) families of the T-cell receptor (TCR) gamma gene. In comparison, patients 16 to 60 years old (n = 21) more commonly had an anterior mediastinal mass (8 [38%]), hepatosplenomegaly (10 [48%]), and lymphadenopathy (16 [76%]). The tumors in these patients commonly used the TCR gamma gene VI or V(II) families (17/25 total rearrangements [68%]). Myeloid antigen expression (5 [24%]) and lineage inappropriate gene rearrangements (4/15 [27%]) were uncommon. Within this group, CD1a expression correlated with age 28 to 60 years. These results illustrate considerable age-related heterogeneity in adult T-ALL, which may reflect differences in tumor cell maturation.

Simultaneous evaluation of T- and B-cell clonality, t(11;14) and t(14;18), in a single reaction by a four-color multiplex polymerase chain reaction assay and automated high-resolution fragment analysis: a method for the rapid molecular diagnosis of lymphoproliferative disorders applicable to fresh frozen and formalin-fixed, paraffin-embedded tissues, blood, and bone marrow aspirates

Current polymerase chain reaction (PCR) methods for the molecular diagnosis of B- and T-cell lymphomas by determination of clonality of immunoglobulin heavy chain (IgH) and T-cell receptor-gamma rearrangements and by detection of the chromosomal translocations t(14;18) and t(11;14), require several laborious and costly PCR assays for each of these diagnostic tests. We have developed a multiplex PCR assay for the simultaneous determination of B- and T-cell clonality and the detection of the chromosomal translocations t(14;18) and t(11;14) in a single reaction, using four-color fluorescence and automated high-resolution fragment analysis. The 26 primers combined in the multiplex PCR correspond to the sequences of >90% of the 69 variables and 6 join IgH genes and 100% of the T-cell receptor-gamma variables and join genes that could participate in the respective rearrangements. In addition, they detect the major and the minor breakpoint regions of the t(14;18) and the major breakpoint region of the t(11;14), and amplify the beta-globin gene as an internal control. The specificity of the multiplex PCR was confirmed by analysis of 39 T-cell lymphomas and 58 B-cell lymphomas, including 11 mantle cell lymphomas bearing the t(11;14) and 25 follicular lymphomas bearing the t(14;18), with known rearrangements and/or translocations. Fifteen samples of reactive lymphadenitis remained negative.

Denaturing HPLC for Identification of Clonal T-Cell Receptor γ Rearrangements in Newly Diagnosed Acute Lymphoblastic Leukemia

Background: Denaturing HPLC (DHPLC) can be used to screen DNA for known and unknown mutations. We describe a novel, HPLC-based method for discrimination among polyclonal, oligoclonal, and/or clonal T-cell receptor γ (TCR-γ) rearrangements in samples from children with newly diagnosed acute lymphoblastic leukemia.

Methods: TCR rearrangements were PCR amplified from initial leukemic samples and, after heteroduplex-induction, the clonality status of each product was evaluated. To attain this, we used DHPLC on a high-resolution micropellicular matrix. Running conditions were established by melting-curve analysis of known clonal and polyclonal products and melting-point prediction software. Elution profiles were studied at 50 °C (native) and, to achieve optimal separation, at different column temperatures between 56 and 64 °C.

Results: For VγI-Jγ1.3/2.3 rearrangements, an analysis temperature of 60 °C with a linear triethylammoniumacetate—acetonitrile gradient separated clonal bands from the polyclonal background amplification. Less than 15% clonal PCR product was detectable in mixtures of initial leukemic cell DNA and polyclonal DNA. Biallelic rearrangements produced two sharp peaks. Clonality of PCR products from 100 initial leukemic samples was completely identified in all investigated cases.

Conclusions: Heteroduplex analysis with standardized DHPLC conditions simplifies the detection of unknown clonal or polyclonal TCR rearrangements in newly diagnosed leukemias. Clonal targets for detection of minimal residual disease are available after a short, automated analysis of PCR amplified rearrangements.

TCR usage in naive and committed alloreactive cells: implications for the understanding of TCR biases in transplantation

The direct pathway of allorecognition is involved in acute allograft rejection and is characterised by TCR-mediated recognition of the MHC framework; this is thought to occur in a peptide-dependent but not peptide-specific manner. In contrast, the indirect pathway is restricted to the recipient's own MHC molecules and prevails in chronic rejection. In this pathway, the peptide has a major influence on the TCR recognition and selects alloreactive T cells with altered TCR Vbeta usage. However, qualitative analysis of Vbeta usage alone might limit our understanding of alloreactivity. The advantages of a combined quantitative assessment of Vbeta mRNA usage are discussed.

Refractory sprue, coeliac disease, and enteropathy-associated T-cell lymphoma. French Coeliac Disease Study Group

BACKGROUND

Adult refractory sprue is a poorly defined disorder. We did a multicentre national study of patients with refractory sprue to characterise their clinical and pathological profile and outcome, and to assess the frequency and prognostic significance of phenotypic and molecular abnormalities in the intraepithelial T-cell population.

METHODS

Patients with severe symptomatic villous atrophy mimicking coeliac disease but refractory to a strict gluten-free diet, and with no initial evidence of overt lymphoma, were diagnosed at gastrointestinal referral centres between 1974 and 1998. Fixed and/or frozen duodenojejunal biopsy samples were reanalysed and immunostained with CD3 and CD8 monoclonal antibodies to find out the phenotype of intraepithelial lymphocytes (IEL). TCRgamma gene rearrangements were assessed on frozen biopsy samples by multiplex fluorescent PCR.

FINDINGS

There were 21 patients with refractory sprue and 20 controls with coeliacs disease. 16 (84%) of 19 assessed patients had an aberrant intraepithelial lymphoid intestinal population expressing intracytoplasmic CD3 but not surface CD8. Clonal intestinal TCRgamma gene rearrangements were found in 13 (76%) of 17 patients assessed; four (out of 12 assessed) had clonal dissemination to the blood. The 16 patients with an aberrant phenotype all had uncontrolled malabsorption; three subsequently developed overt T-cell lymphoma, and eight died. The three (16%) patients without aberrant clonal IEL made a complete clinical and histological recovery with steroid therapy plus a gluten-free diet.

INTERPRETATION

An immunophenotypically aberrant clonal intraepithelial T-cell population (similar to that of most cases of enteropathy-associated T-cell lymphoma) can be found in up to 75% of patients with refractory coeliac sprue; its identification by simple diagnostic techniques represents a marker of poor outcome (including occurrence of overt T-cell lymphoma). We suggest that refractory sprue associated with an aberrant clonal IEL may be the missing link between coeliac disease and T-cell lymphoma and may be classified as cryptic enteropathy-associated T-cell lymphoma.

Non-Hodgkin's Lymphoma: Molecular Features of B Cell Lymphoma

The rapid increase in the incidence of the B cell non-Hodgkin's lymphomas (NHL) and improved understanding of the mechanisms involved in their development renders timely a review of the theoretical and practical aspects of molecular abnormalities in B cell NHL.

In Section I, Dr. Macintyre addresses the practical aspects of the use of molecular techniques for the diagnosis and therapeutic management of patients with B cell NHL. While detection of clonal Ig rearrangements is widely used to distinguish reactive from malignant lymphoproliferative disorders, molecular informativity is variable. The relative roles of cytogenetic, molecular and immunological techniques in the detection of genetic abnormalities and their protein products varies with the clinical situation. Consequently, the role of molecular analysis relative to morphological classification is evolving. Integrated diagnostic services are best equipped to cope with these changes. Recent evidence that large scale gene expression profiling allows improved prognostic stratification of diffuse large cell lymphoma suggests that the choice of diagnostic techniques will continue to change significantly and rapidly.

In Section II, Dr. Willerford reviews current understanding of the mechanisms involved in immunoglobulin (Ig) gene rearrangement during B lymphoid development and the way in which these processes may contribute to Ig-locus chromosome translocations in lymphoma. Recent insights into the regulation of Ig gene diversification indicate that genetic plasticity in B lymphocytes is much greater than previously suspected. Physiological genomic instability, which may include isotype switching, recombination revision and somatic mutation, occurs in germinal centers in the context of immune responses and may explain longstanding clinical observations that link immunity and lymphoid neoplasia. Data from murine models and human disorders predisposing to NHL have been used to illustrate these issues.

In Section III, Dr. Morris reviews the characteristics and consequences of deregulation of novel “proto-oncogenes” involved in B cell NHL, including PAX5 (chromosome 9p 13), BCL8 (15q11-q13), BCL9, MUC1, FcγRIIB and other 1q21-q22 genes and BCL10 (1p22). The AP12-MLT/MALT1 [t(11;18)(q21;q21)] fusion transcript is also described.

Non-Hodgkin's Lymphoma: Molecular Features of B Cell Lymphoma

The rapid increase in the incidence of the B cell non-Hodgkin's lymphomas (NHL) and improved understanding of the mechanisms involved in their development renders timely a review of the theoretical and practical aspects of molecular abnormalities in B cell NHL.

In Section I, Dr. Macintyre addresses the practical aspects of the use of molecular techniques for the diagnosis and therapeutic management of patients with B cell NHL. While detection of clonal Ig rearrangements is widely used to distinguish reactive from malignant lymphoproliferative disorders, molecular informativity is variable. The relative roles of cytogenetic, molecular and immunological techniques in the detection of genetic abnormalities and their protein products varies with the clinical situation. Consequently, the role of molecular analysis relative to morphological classification is evolving. Integrated diagnostic services are best equipped to cope with these changes. Recent evidence that large scale gene expression profiling allows improved prognostic stratification of diffuse large cell lymphoma suggests that the choice of diagnostic techniques will continue to change significantly and rapidly.

In Section II, Dr. Willerford reviews current understanding of the mechanisms involved in immunoglobulin (Ig) gene rearrangement during B lymphoid development and the way in which these processes may contribute to Ig-locus chromosome translocations in lymphoma. Recent insights into the regulation of Ig gene diversification indicate that genetic plasticity in B lymphocytes is much greater than previously suspected. Physiological genomic instability, which may include isotype switching, recombination revision and somatic mutation, occurs in germinal centers in the context of immune responses and may explain longstanding clinical observations that link immunity and lymphoid neoplasia. Data from murine models and human disorders predisposing to NHL have been used to illustrate these issues.

In Section III, Dr. Morris reviews the characteristics and consequences of deregulation of novel “proto-oncogenes” involved in B cell NHL, including PAX5 (chromosome 9p 13), BCL8 (15q11-q13), BCL9, MUC1, FcγRIIB and other 1q21-q22 genes and BCL10 (1p22). The AP12-MLT/MALT1 [t(11;18)(q21;q21)] fusion transcript is also described.