T-cell receptor gene rearrangements as clinical markers of human T-cell lymphomas

Role of cytokine in malignant T-cell metabolism and subsequent alternation in T-cell tumor microenvironment

T cells are an important component of adaptive immunity and T-cell-derived lymphomas are very complex due to many functional sub-types and functional elasticity of T-cells. As with other tumors, tissues specific factors are crucial in the development of T-cell lymphomas. In addition to neoplastic cells, T- cell lymphomas consist of a tumor micro-environment composed of normal cells and stroma. Numerous studies established the qualitative and quantitative differences between the tumor microenvironment and normal cell surroundings. Interaction between the various component of the tumor microenvironment is crucial since tumor cells can change the microenvironment and vice versa. In normal T-cell development, T-cells must respond to various stimulants deferentially and during these courses of adaptation. T-cells undergo various metabolic alterations. From the stage of quiescence to attention of fully active form T-cells undergoes various stage in terms of metabolic activity. Predominantly quiescent T-cells have ATP-generating metabolism while during the proliferative stage, their metabolism tilted towards the growth-promoting pathways. In addition to this, a functionally different subset of T-cells requires to activate the different metabolic pathways, and consequently, this regulation of the metabolic pathway control activation and function of T-cells. So, it is obvious that dynamic, and well-regulated metabolic pathways are important for the normal functioning of T-cells and their interaction with the microenvironment. There are various cell signaling mechanisms of metabolism are involved in this regulation and more and more studies have suggested the involvement of additional signaling in the development of the overall metabolic phenotype of T cells. These important signaling mediators include cytokines and hormones. The impact and role of these mediators especially the cytokines on the interplay between T-cell metabolism and the interaction of T-cells with their micro-environments in the context of T-cells lymphomas are discussed in this review article.

Molecular diagnosis of T-cell lymphoma: a correlative study of PCR-based T-cell clonality assessment and targeted NGS

Immunomorphological diagnosis of T-cell lymphoma (TCL) may be challenging, especially on needle biopsies. Multiplex polymerase chain reaction (PCR) assays to assess T-cell receptor (TCR) gene rearrangements are now widely used to detect T-cell clones and provide diagnostic support. However, PCR assays detect only 80% of TCL, and clonal lymphocyte populations may also appear in nonneoplastic conditions. More recently, targeted next-generation sequencing (t-NGS) technologies have been deployed to improve lymphoma classification. To the best of our knowledge, the comparison of these techniques' performance in TCL diagnosis has not been reported yet. In this study, 82 TCL samples and 25 nonneoplastic T-cell infiltrates were divided into 2 cohorts (test and validation) and analyzed with both multiplex PCR and t-NGS to investigate TCR gene rearrangements and somatic mutations, respectively. The detection of mutations appeared to be more specific (100.0%) than T-cell clonality assessment (41.7%-45.5%), whereas no differences were observed in terms of sensitivity (95.1%-97.4%). Furthermore, t-NGS provided a reliable basis for TCL diagnosis in samples with partially degraded DNA that was impossible to assess with PCR. Finally, although multiplex PCR assays appeared to be less specific than t-NGS, both techniques remain complementary, as PCR recovered some t-NGS negative cases.

Next-Generation Sequencing Technologies for Early-Stage Cutaneous T-Cell Lymphoma

The diagnosis of early stage cutaneous T-cell lymphoma is often difficult, particularly in mycosis fungoides (MF), because the clinical presentation, histological findings, and laboratory findings of MF resemble those of inflammatory skin diseases such as atopic dermatitis, psoriasis, and parapsoriasis en plaque. Furthermore, MF sometimes occurs with or after these inflammatory skin diseases. The current diagnostic criteria heavily rely on clinical impressions along with assessments of T cell clonality. To make a diagnosis of early-stage MF, the detection of a malignant clone is critical. T cell receptor (TCR) gene rearrangements have been detected by southern blotting or polymerase chain reaction for this purpose, but the results of these methods are insufficient. High-throughput TCR sequencing has provided insights into the complexities of the immune repertoire. Accordingly, his technique is more sensitive and specific than current methods, making it useful for the detection of early lesions and monitoring responses to therapy.

The Value of T-Cell Receptor γ (TRG) Clonality Evaluation by Next-Generation Sequencing in Clinical Hematolymphoid Tissues

OBJECTIVES

To evaluate feasibility of assessing T-cell receptor γ (TRG) clonality by next-generation sequencing (NGS) in hematolymphoid tissues.

METHODS

We evaluated TRG clonality using NGS and polymerase chain reaction (PCR) assays in blood, bone marrow, and formalin-fixed, paraffin-embedded tissues in 41 archived cases, including 21 benign cases with no history of any lymphoproliferative disorders (LPDs), 16 LPDs (nine mature T-cell neoplasms, seven mature B-cell neoplasms and immune dysregulation-associated LPDs), and four atypical LPDs from 22 females and 19 males with a median age of 58 (range, 9-87) years.

RESULTS

(1) NGS analyzed TRG sequence and peak ratios, and it had a greater sensitivity than PCR. (2) NGS identified small clones, including biallelic or monoallelic, and minimum clonal percentages (range, ~2.4% to ~69%) within all T cells. (3) We provide our strategy and criteria for evaluating NGS results. (4) We describe every case, with definitive evaluation of TRG clonality in 100% cases by NGS.

CONCLUSIONS

TRG clonality evaluation by NGS provides greater clinical utility than PCR.

Adult T-Cell Leukemia/Lymphoma

Adult T-cell lymphoma/leukemia (ATL) is a rare T-cell lymphoproliferative neoplasm caused by human T-lymphotrophic virus 1. In its more common, aggressive forms, ATL carries one of the poorest prognoses of the non-Hodgkin lymphomas. The disease has clinical subtypes (ie, acute, lymphoma, chronic, and smoldering forms) defined by the presenting features, and therefore, the clinical course can vary. For the smoldering and lower-risk chronic forms, combinations involving antiviral therapies have shown some success. However, in many patients, the more indolent forms will evolve into the more aggressive subtypes. In the more aggressive acute, lymphoma, and higher-risk chronic forms, the literature supports initial treatment with combination chemotherapy followed by allogeneic transplantation as a potentially curative approach. Recently, mogamulizumab and lenalidomide have shown promise in the treatment of ATL. With better understanding of the molecular drivers of this disease, we hope that the therapeutic landscape will continue to expand.

T cell clonality assessment: past, present and future

T cell clonality testing has important clinical and research value, providing a specific and reproducible assessment of clonal diversity in T cell proliferations. Here we review the conceptual foundations of T cell clonality assays, including T cell ontogeny and T cell receptor structure and function; we also provide an introduction to T cell receptor genomics and the concept of the T cell clonotype. This is followed by a review of historical and current methods by which T cell clonality may be assayed, including current assay limitations. Some of these assay limitations have been overcome by employing next-generation sequencing (NGS)-based technologies that are becoming a mainstay of modern molecular pathology. In this vein, we provide an introduction to NGS technologies, including a review of the preanalytical, analytical and postanalytical technologies relevant to T cell clonality NGS assays.

T-cell receptor profiling in cancer

Immunosequencing is a platform technology that allows the enumeration, specification and quantification of each and every B- and/or T-cell in any biologic sample of interest. Thus, it provides an assessment of the level and distribution of all the clonal lymphocytes in any sample, and allows "tracking" of a single clone or multiple clones of interest over time or from tissue to tissue within a given patient. It is based on bias-controlled multiplex PCR and high-throughput sequencing, and it is highly accurate, standardized, and sensitive. In this review, we provide evidence that immunosequencing is becoming an important analytic tool for the emerging field of immune-oncology, and describe several applications of this approach, including the assessment of residual disease post therapy in lymphoid malignancies, the prediction of response to immunotherapeutics of solid tumors containing tumor infiltrating lymphocytes, the identification of clonal responses in vaccination, infectious disease, bone marrow reconstitution, and autoimmunity, and the exploration of whether there are population-based stereotyped responses to certain exposures or interventions.

The evolution of clonality testing in the diagnosis and monitoring of hematological malignancies

Currently, distinguishing between benign and malignant lymphoid proliferations is based on a combination of clinical characteristics, cyto/histomorphology, immunophenotype and the identification of well-defined chromosomal aberrations. However, such diagnoses remain challenging in 10-15% of cases of lymphoproliferative disorders, and clonality assessments are often required to confirm diagnostic suspicions. In recent years, the development of new techniques for clonality detection has allowed researchers to better characterize, classify and monitor hematological neoplasms. In the past, clonality was primarily studied by performing Southern blotting analyses to characterize rearrangements in segments of the IG and TCR genes. Currently, the most commonly used method in the clinical molecular diagnostic laboratory is polymerase chain reaction (PCR), which is an extremely sensitive technique for detecting nucleic acids. This technique is rapid, accurate, specific, and sensitive, and it can be used to analyze small biopsies as well as formalin-fixed paraffin-embedded samples. These advantages make PCR-based approaches the current gold standard for IG/TCR clonality testing. Since the completion of the first human genome sequence, there has been a rapid development of technologies to facilitate high-throughput sequencing of DNA. These techniques have been applied to the deep characterization and classification of various diseases, patient stratification, and the monitoring of minimal residual disease. Furthermore, these novel approaches have the potential to significantly improve the sensitivity and cost of clonality assays and post-treatment monitoring of B- and T-cell malignancies. However, more studies will be required to demonstrate the utility, sensitivity, and benefits of these methods in order to warrant their adoption into clinical practice. In this review, recent developments in clonality testing are examined with an emphasis on highly sensitive systems for improving diagnostic workups and minimal residual disease assessments.

A parallel comparison of T-cell clonality assessment between an in-house PCR assay and the BIOMED-2 assay leading to an efficient and cost-effective strategy

AIMS

Diagnosis of T-cell lymphoproliferation is sometimes challenging, and in certain instances pathologists rely heavily on the clonality assessment results of T-cell receptor (TCR) gene rearrangement (TCR-GR). Many investigators have designed various in-house primer sets for PCR-based study targeting different loci of TCR genes. In recent years, the commercial BIOMED-2 protocols have become available. The in-house primers are very cheap while the BIOMED-2 primers are expensive. This parallel study aimed to compare the sensitivity of the in-house TCRG primers (two reactions) and the BIOMED-2 TCR primers (six reactions) in an attempt to develop a sensitive and cost-effective strategy for TCR-GR assessment.

METHODS

PCR-based analysis was performed on 69 samples of T-lineage neoplasms including 60 formalin-fixed paraffin-embedded (FFPE) tissues, 5 samples from peripheral blood (PB) and 4 samples from bone marrow (BM) aspirate.

RESULTS

Forty-seven (78%) FFPE and all PB or BM aspirate samples yielded control DNA products suitable for clonality assessment including 4 precursor and 50 mature T-cell neoplasms. The detection rates of clonal TCR-GR were 63% (34/54) by the two in-house TCRG primers, 85% (46/54) by all six BIOMED-2 reactions, 91% (49/54) by combining the in-house and BIOMED-2 TCRG reactions and 94% (51/54) by combining the in-house and all BIOMED-2 reactions. By using the in-house and BIOMED-2 TCRG reactions with a total of four tubes, clonal TCR-GR was detected in 91% of the cases. The reagent cost for this combination was one-third of that for the six BIOMED-2 reactions and the detection rate was also higher than the latter alone (91% vs 85%).

CONCLUSIONS

As the in-house primers were custom made and are much cheaper than the commercial kits, the authors concluded that this four-tube strategy was cost-effective and efficient for TCR-GR clonality assessment.

CNS lymphomatoid granulomatosis with lymph node and bone marrow involvements

Lymphomatoid granulomatosis (LYG) in the CNS is an uncommon lymphoproliferative disease with characteristic angiocentric lymphoreticular proliferative and granulomatous lesions exhibiting low-grade malignant potential. Here we report a rare case of CNS-LYG, which disseminated to the lymph node and bone marrow. A 50-year-old man was diagnosed with CNS-LYG based on brain biopsy showing perivascular infiltration of CD3-positive small T-lymphocytes without overt nuclear atypism. Eight months after the initial neurological symptoms, inguinal lymph node swelling was found and histopathologically diagnosed as peripheral T-cell lymphoma. TCRgamma-gene rearrangement study using both paraffin-embedded specimens of brain and inguinal lymph node demonstrated an identical clonal band. Considering the clinical course, we concluded lymph node involvement of CNS-LYG, suggesting the malignant potential of CNS-LYG.

Extracorporeal photochemotherapy in the treatment of cutaneous T cell lymphoma and autoimmune disorders affecting the skin

Extracorporeal photochemotherapy (ECPCT) is a new form of chemoimmunotherapy which involves the ex vivo exposure of malignant peripheral blood cells to 8-methoxypsoralen (8-MOP) and ultraviolet A (UVA) radiation followed by reinfusion of the treated cells. This treatment has resulted in an unprecedented number of prolonged remissions in patients with therapeutically resistant forms of cutaneous T cell lymphoma (CTCL) characterized by the systemic dissemination of a clonal population of malignant helper T lymphocytes. Although the mechanism of the beneficial effect is uncertain, an immune reaction to the reinfused modified T cells probably results in tumour regression. Because the T cell antigen receptor (TCR) is an immunogenic structure and because an identical TCR is present on the entire clonal population of malignant T cells in each individual with CTCL, modification of this structure represents the most likely target for the effects of 8-MOP and UVA. Understanding of the precise events leading to tumour regression in CTCL during treatment with ECPCT may lead to the expanded use of this therapy for other lethal haemopoietic malignancies.

Role of ancillary techniques in diagnosing and subclassifying non-Hodgkin's lymphomas on fine needle aspiration cytology

Non-Hodgkin's lymphomas (NHL) are tumours of the lymphoid cells. During the process of development of lymphoid cells, neoplasia may evolve at any point. Neoplastic cells usually carry the imprint of cell of origin at the stage of origin. Various types of NHL may have similar morphology with wide variation in origin, immunophenotype and other biological features. Different ancillary laboratory techniques may help to overcome the limitations of morphology in this aspect. The commonly used ancillary techniques in lymphomas are immunocytochemistry (IC), flow cytometry, Southern blot (SB) technique, polymerase chain reaction (PCR) and fluorescent in situ hybridization (FISH). In addition, laser scanning cytometry (LSC) and DNA microarray technologies are in the research phase. Various laboratory techniques are used for immunophenotyping, demonstration of monoclonality, identification of chromosomal translocation, assessment of cell kinetics and expression of mRNA in the tumour cells. Flow cytometry helps in rapid immunophenotying of NHL and it has an added advantage over IC in recognizing the co-expression of CD markers. Fine needle aspiration cytology (FNAC) combined with flow immunophenotyping may help us to diagnose and subclassify certain NHLs, such as follicular lymphoma and mantle cell lymphoma, which were previously recognized as pure morphological entities. Loss of morphology is one of the important limitations of flow cytometry. LSC can overcome this limitation by studying morphology along with the immunophenotyping pattern of individual cells. Chromosomal changes in NHL can be identified by SB, PCR and FISH. Molecular diagnosis of NHL helps in diagnosis, subclassification, prognostic assessment and even in planning of therapy. DNA microarray is a relatively newer and promising technology. It gives information about the expression of several thousands of genes in a tumour in a single experiment. In the near future, FNAC combined with ancillary techniques may play a major role in diagnosis, subclassification and management of lymphomas.

Structured polychotomous machine diagnosis of multiple cancer types using gene expression

MOTIVATION

The problem of class prediction has received a tremendous amount of attention in the literature recently. In the context of DNA microarrays, where the task is to classify and predict the diagnostic category of a sample on the basis of its gene expression profile, a problem of particular importance is the diagnosis of cancer type based on microarray data. One method of classification which has been very successful in cancer diagnosis is the support vector machine (SVM). The latter has been shown (through simulations) to be superior in comparison with other methods, such as classical discriminant analysis, however, SVM suffers from the drawback that the solution is implicit and therefore is difficult to interpret. In order to remedy this difficulty, an analysis of variance decomposition using structured kernels is proposed and is referred to as the structured polychotomous machine. This technique utilizes Newton-Raphson to find estimates of coefficients followed by the Rao and Wald tests, respectively, for addition and deletion of import vectors.

RESULTS

The proposed method is applied to microarray data and simulation data. The major breakthrough of our method is efficiency in that only a minimal number of genes that accurately predict the classes are selected. It has been verified that the selected genes serve as legitimate markers for cancer classification from a biological point of view.

AVAILABILITY

All source codes used are available on request from the authors.

Usefulness of Cutaneous T-Cell Clonality Analysis for the Diagnosis of Cutaneous T-Cell Lymphoma in Patients With Erythroderma

Context.—Demonstration of a dominant T-cell clone in skin biopsy specimens by a molecular assay constitutes an additional diagnostic criterion to differentiate cutaneous T-cell lymphomas (CTCLs) from inflammatory dermatoses.

Objective.—To determine which patients, depending on their clinical presentations, could most benefit from a cutaneous T-cell clonality analysis in addition to histopathologic analysis for the diagnosis of CTCL.

Design.—Comparison of sensitivity and specificity of histopathologic analysis and a combination of this method and the detection of a T-cell receptor γ chain gene rearrangement by polymerase chain reaction denaturing gradient gel electrophoresis performed on skin biopsy specimens obtained at initial presentation.

Patients.—One hundred forty consecutive patients were classified into 4 groups, depending on their clinical presentation: (1) eczematous patches suggestive of early-stage mycosis fungoides (MF) (IA and IB of the TNM classification) (n = 42); (2) plaques, nodules, or tumors that arise on or are associated with plaques suggestive of late-stage MF (IIB and III of the TNM classification) (n = 16); (3) erythroderma (n = 50); and (4) nodules or tumors that arise in normal skin, suggestive of non-MF CTCL (n = 32).

Results.—When compared with histopathologic examination, the addition of clonality analysis increased the sensitivity of CTCL diagnosis in all groups of patients except those with cutaneous lesions suggestive of late-stage MF, because the diagnosis was made based on histopathologic analysis alone in 100% of these cases. The main increase in sensitivity of CTCL diagnosis was observed in patients with erythroderma: 62% with histopathologic analysis alone to 87% with the combination of both methods (P = .04). Diagnostic specificity of molecular assays decreased from 100% to 76% (P = .01) in patients with patch lesions and from 100% to 70% (P = .04) in patients with nodules that occurred in normal skin due to the detection of a T-cell clone in 6 patients with follicular mucinosis without a histologic pattern of MF and in 5 of 20 cases of T-cell pseudolymphoma (25%), respectively. In contrast, a T-cell clone was not detected in the 34 patients with erythroderma of inflammatory origin.

Conclusion.—Polymerase chain reaction analysis of cutaneous T-cell clonality could be useful for the diagnosis of CTCL in patients who present with erythroderma.

Febrile ulceronecrotic Mucha-Habermann disease with clonality: A cutaneous T-cell lymphoma entity?

Febrile ulceronecrotic Mucha-Habermann disease (FUMHD) is a severe variant of pityriasis lichenoides et varioliformis acuta (PLEVA). PLEVA patients only very rarely have systemic signs; the cutaneous lesions are usually asymptomatic, but may be pruritic and may heal with scarring. FUMHD often starts out as classic PLEVA, but goes on to develop widespread ulceronecrotic lesions and is associated with a high mortality rate. Whether Pityriasis lichenoides chronica (PLC) and PLEVA form a spectrum rather than single entities of clonal lymphoproliferative diseases has been discussed. Recently, it has been proposed that FUMHD, too, is a clonal lymphoproliferative disorder. Here, we report two cases of FUMHD with monoclonal T-cell population, as detected by Southern blot analysis. We propose that clonal FUMHD represents a cutaneous T-cell lymphoma entity.

A simple clinical scoring system to improve the sensitivity and standardization of the diagnosis of mycosis fungoides type cutaneous T-cell lymphoma: logistic regression of clinical and laboratory data

BACKGROUND

The diagnosis of mycosis fungoides (MF) is notoriously difficult to establish because in the early stages, histological features may be nonspecific or merely suggestive.

OBJECTIVES

To standardize the diagnosis of MF.

METHODS

We studied 138 patients with suspected MF referred over a 7-year period to a university department of a dermatology-based cutaneous lymphoma clinic. Six diagnostic criteria were evaluated: clinical morphology, clinical distribution, skin biopsy T-cell receptor gene rearrangement (TCR-GR), skin biopsy pan T-cell marker loss > or = 2, skin biopsy CD4/CD8 ratio > or = 6, and skin biopsy diffuse epidermal HLA-DR expression. These six clinical and laboratory criteria were compared by logistic regression analysis in patients with histologically diagnosed MF and those with benign disease.

RESULTS

Of the 138 patients, 74 had histology of MF, 47 of benign dermatoses and 17 were indeterminate. Close associations were found between a histological diagnosis of MF and TCR-GR (odds ratio 14.4), classical morphology (7.5), classical distribution (2.5) and diffuse epidermal HLA-DR expression (2.8). Logistic regression models were developed depending on the availability of data (either TCR-GR or HLA-DR). Probabilities for correctly diagnosing MF compared with histology as the 'gold standard' were derived from these logistic regression models. A scoring system assigning point values based on these probabilities was then created in order to assist the clinician in making the diagnosis. If using TCR-GR data, a positive TCR-GR = 2.5 points, the presence of classical morphology = 2.0 points, and the presence of classical distribution = 1.5 points. A total score of > or = 3.5 points assigns a high probability (> 85%) of having MF. If using HLA-DR expression, then the presence of classical morphology = 2.5 points, a positive diffuse epidermal HLA-DR expression = 2.0 points, and the presence of classical distribution = 1.5 points. In this case, a total score of > or = 4.0 points assigns a high probability (> 85%) of MF.

CONCLUSIONS

The logistic regression models and scoring systems integrate clinical and laboratory assessments, allow rapid probability estimation, and provide a threshold for the diagnosis of MF in an objective, standardized manner.

The relevance of peripheral blood T-helper 1 and 2 cytokine pattern in the evaluation of patients with mycosis fungoides and Sézary syndrome

BACKGROUND

There is evidence that a T-helper (Th) 2 cytokine pattern dominates in the peripheral blood as well as in tissue of patients with Sézary syndrome (SS), and that the malignant clone is of Th2 phenotype. However, there are conflicting studies on the cytokine pattern in the peripheral blood in different stages of cutaneous T-cell lymphoma (CTCL).

OBJECTIVES

To examine, by means of flow cytometry (FC), the Th1/Th2 cytokine profile [cytoplasmic interferon (IFN)-gamma/interleukin (IL)-4] in peripheral blood T cells from patients with mycosis fungoides (MF) and SS, the most common forms of CTCL, and to correlate their expression with clinical stage, clonality and T-cell immunophenotype changes in order to evaluate their relevance in CTCL progression.

METHODS

We investigated by FC the percentage of CD3+ T cells expressing cytoplasmic IFN-gamma and IL-4 after stimulation in blood specimens of 43 CTCL patients (32 stage I-II and 11 stage III-IV), eight of whom were erythrodermic. Next, we compared cytoplasmic IFN-gamma and IL-4 expression between patients of different stages and controls, and correlated our findings to T-cell receptor (TCR)-gamma gene rearrangement, used as a marker of clonality, and changes in T-cell immunophenotype (CD4+, CD8+, CD4+/CD7-, CD4+/CD25+) and natural killer cells. Polymerase chain reaction amplification of the TCR-gamma gene was performed in 41 blood and 26 skin specimens. We also examined the cytokine expression pattern in patients with erythrodermic MF and SS.

RESULTS

A significantly higher frequency of CD3+/IL-4+ T cells was found in late (III-IV) compared with early (I-II) CTCL patients (P = 0.002) or controls (P < 0.001). There were significant positive correlations between the percentages of CD3+/IL-4+ and the percentages of CD3+/CD4+ T cells (r = 0.385, P = 0.05), CD4+/CD7- T cells (r = 0.335, P < 0.05) and CD4+/CD25+ T cells (r = 0.433, P = 0.01); there was a negative correlation between the percentages of CD3+/IL-4+ and CD3+/CD8+ T cells (r = -0.463, P = 0.005) and a positive correlation between the percentages of CD3+/IFN-gamma+ and CD3+/CD8+ T cells (r = 0.368, P = 0.02). Increased percentages of CD3+/IL-4+, CD3+/CD4+ and CD4+/CD7- T lymphocytes were associated with the presence of clonality (P = 0.025, P < 0.001 and P = 0.0031, respectively). All independent variables showed a statistically significant difference between SS and erythrodermic MF patients, or controls, apart from cytoplasmic IL-4, which was high both in erythrodermic MF and SS patients compared with controls (P = 0.003 and P = 0.008, respectively). In multiple regression logistic analysis, the probability of belonging to advanced CTCL stages was associated only with increased cytoplasmic IL-4 (P = 0.007, odds ratio 1.13, 95% confidence interval 1.033-1.229).

CONCLUSIONS

Increased T-cell cytoplasmic IL-4 is more frequent in late CTCL stages, correlates with T-cell immunophenotype changes found in advanced disease and is associated with clonality. Increased cytoplasmic IL-4 is frequent both in erythrodermic MF and SS patients, in contrast to other variables found increased only in SS, suggesting that IL-4 may be an early indicator of disease progression. Moreover, our results show that increased cytoplasmic IL-4 is the sole predictor of advanced CTCL disease and confirm the relevance of FC determination of IL-4 in the routine evaluation of CTCL cases.

Detection of minimal residual disease

A high percentage of patients with leukemia, lymphoma, and solid tumors achieve a complete clinical remission after initial treatment, but the majority of these patients will finally relapse from residual tumor cells detectable in clinical remission only by the most sensitive methods. The in vitro amplification of tumor-specific DNA or RNA sequences by polymerase chain reaction (PCR) allows identification of a few neoplastic cells in 10(4) to 10(6) normal cells. Depending on the underlying malignant disease and therapeutic treatment, the presence of residual tumor cells in an individual patient may herald relapse, but a long-term stable situation or slowly vanishing tumor cells are also possible. Molecular monitoring of residual leukemia and lymphoma cells by quantitative PCR techniques has provided important information about the effectiveness of treatment and the risk of recurrent disease as shown by minimal residual disease (MRD) analysis in patients with various malignant diseases. Such diseases include childhood acute lymphoblastic leukemia, after induction therapy; acute promyelocytic leukemia, during and after chemotherapy; and chronic myelogenous leukemia, during treatment with alpha-interferon and after allogeneic bone marrow transplantation. Evaluation of the predictive value of the detection of MRD has to take into account its evolution and course, the pathogenesis, biology, and natural course of the underlying malignant disease, the molecular genetic lesion, and finally, the type of treatment. Quantification of minimal residual cells by the recently developed real-time quantitative PCR technique will surely have a major impact on our therapeutic strategies for patients with leukemia, lymphomas, and solid tumors. Based on quantitative PCR data, the terms molecular remission and molecular relapse have to be exactly defined and validated in prospective clinical trials to assess the biological and clinical significance of MRD in various types of malignancies.

Update on erythrodermic cutaneous T-cell lymphoma: report of the International Society for Cutaneous Lymphomas

Two conferences were sponsored by the International Society for Cutaneous Lymphomas (ISCL) to gain consensus on definitions and terminology for clinical use in erythrodermic cutaneous T-cell lymphoma (E-CTCL). Three subsets of E-CTCL were defined: Sézary syndrome ("leukemic phase" E-CTCL), erythrodermic mycosis fungoides (secondary E-CTCL that develops in patients with mycosis fungoides), and E-CTCL, not otherwise defined. The hematologic criteria recommended for Sézary syndrome are intended to identify patients with a worse prognosis compared with the other E-CTCL subsets and consist of one or more of the following: (1) an absolute Sézary cell count of 1000 cells/mm3 or more; (2) a CD4/CD8 ratio of 10 or higher caused by an increase in circulating T cells and/or an aberrant loss or expression of pan-T cell markers by flow cytometry; (3) increased lymphocyte counts with evidence of a T-cell clone in the blood by the Southern blot or polymerase chain reaction technique; or (4) a chromosomally abnormal T-cell clone. For staging purposes, it is proposed that these criteria define the B2 blood rating and that the B2 rating be considered equivalent to nodal involvement.

Immunoblotting detection of gamma-catenin (plakoglobin) antibody in the serum of a patient with paraneoplastic pemphigus

We report a patient with paraneoplastic pemphigus associated with a thymic tumour. Immunoblot study using affinity-purified gamma-catenin protein revealed that his serum recognized gamma-catenin (plakoglobin) in epidermal, thymic tumour and mouse bladder extracts.

Primary non-Hodgkin's lymphoma of the jaws: immunohistochemical and genetic review of 10 cases

PURPOSE

Non-Hodgkin's lymphoma (NHL) comprises a group of malignant lymphoproliferative diseases characterized by clonal expansion of lymphocytes at various levels of ontogenetic development. The aim of this study was to review the immunohistochemical and cytogenetic features of 10 cases of NLH of the jaws to determine their respective derivation.

PATIENTS AND METHODS

Histopathologic and immunohistochemical review of 10 cases of large-cell lymphomas of the jaws, together with Southern blot analysis of 2 of the cases, was performed and results compared with the findings in the literature.

RESULTS

In the 10 cases studied, the average age of onset of the NHL was 51 years, with a male-to-female ratio of 3:2. Tumefaction was the first clinical sign of disease. Eight of 10 cases were high-grade, large-cell NHLs, centroblastic type. Two cases were high-grade, large-cell NHL, immunoblastic type.

CONCLUSION

The immunohistochemical and Southern blot data remain the principal laboratory aids in the diagnosis and characterization of NHL, and they provide critical information for guiding clinicians to the appropriate treatment protocol for these malignancies.

Detection of a peripheral blood T cell clone is an independent prognostic marker in mycosis fungoides

T cell receptor gene analysis is a sensitive method for assessment of peripheral blood involvement in mycosis fungoides. This study uses polymerase chain reaction/single-strand conformational polymorphism (PCR/SSCP) analysis of the T cell receptor gamma gene and relates the results to skin stage and outcome in mycosis fungoides. Seventy-five peripheral blood samples from 66 patients were obtained from 1990 onwards and subjected to PCR/SSCP. Both Southern blot analysis and PCR/SSCP analysis were performed on 63 samples from 56 patients. Fourteen patients had T1 disease (12 IA, two IIA), 20 T2 (14 IB, five IIA, one IVA), 29 T3 (24 IIB, two IVA, three IVB, two patients tested at both T2 and T3), and five T4 (all III). The percentage of positive samples was higher with PCR/SSCP than with Southern blot analysis (29 of 63 vs eight of 63 samples, p < 0.001), and the percentage of positive samples increased with each stage (21% at T1, 35% at T2, 58% at T3, and 71% at T4). Proportional hazards analysis corrected for age, skin, and lymph node stage showed that the presence of a peripheral blood clone is associated with a worse outcome (p = 0.03, CI 1.1-6.03). These results indicate that the presence of a peripheral blood clone is an independent prognostic variable in patients with mycosis fungoides after correcting for age, skin, and lymph node stage, and that peripheral blood involvement is present in a large proportion of patients with early stage mycosis fungoides.

KEYWORDS

polymerase chain reaction/single-strand conformational polymorphism/T cell receptor gene rearrangement. J Invest Dermatol 114:117-121, 2000

Overview of the role of molecular methods in the diagnosis of malignant lymphomas

OBJECTIVE

To review the role of molecular genetics in the diagnosis of malignant lymphomas.

DATA SOURCES AND STUDY SELECTION

Primary research studies and reviews published in the English literature that focus on molecular genetics and malignant lymphoma, in particular, clonality, chromosomal translocations, tumor suppressor genes, and Hodgkin disease.

DATA EXTRACTION AND SYNTHESIS

Molecular genetics has an important role in the assessment of malignant lymphomas. Clonality, detected by Southern blot analysis or the polymerase chain reaction, is helpful for establishing the diagnosis of lymphoma in lesions with ambiguous morphologic and immunophenotypic findings. Southern blot analysis is the "gold standard" for clonality assessment, but the process is labor-intensive and time-consuming. Polymerase chain reaction analysis is more convenient, but a potentially significant false-negative rate exists in the analysis of some antigen receptor genes as a result of using consensus primers and the process of somatic hypermutation. Chromosomal translocations, which result in oncogene activation, occur in many types of B- and T-cell lymphomas, and their detection is helpful in classification as well as in establishing a diagnosis of malignancy. Gene rearrangements and chromosomal translocations also can be used to monitor minimal residual disease. Tumor suppressor genes, although their analysis is relatively less useful for diagnosis, are involved in both pathogenesis and tumor progression and will be more important diagnostically as this field continues to expand. Molecular genetic analysis has played a major role in improving our understanding of Hodgkin disease.

CONCLUSIONS

Molecular genetic tests are currently important ancillary tools for the diagnosis and classification of malignant lymphomas, and their role is likely to increase in the future.

Demonstration of Frequent Occurrence of Clonal T Cells in the Peripheral Blood But Not in the Skin of Patients With Small Plaque Parapsoriasis

Clinical, immunohistological, and molecular biological data suggest the chronic dermatosis small plaque parapsoriasis (SPP) to be a precursor of mycosis fungoides (MF). However, most data are contradictory and confusing due to inexact definition of SPP. Recently, clonal T cells were detected in skin and blood samples of early MF. Because demonstration of identical T-cell clones in skin and blood of SPP patients would indicate a close relationship of SPP to MF, we investigated the clonality of skin and blood specimens from 14 well-defined SPP patients. By a polymerase chain reaction (PCR) amplifying T-cell receptor γ rearrangements and subsequent high-resolution electrophoresis, clonal T cells were detected in 9 of 14 initial and 32 of 49 follow-up blood samples, but in 0 of 14 initial skin specimens. Even a clone-specific PCR showing the persistence of the initial blood T-cell clone in 20 of 20 follow-up samples, failed to detect the T-cell clone in the skin. In 2 patients, the clonal T cells were shown to be CD4+. For the first time, the majority of SPP patients was shown to carry a T-cell clone in the peripheral blood. Although a relation between circulating clonal T cells and SPP cannot directly be proven by the applied techniques, our results indicate blood T-cell clonality to be a characteristic feature of SPP and CTCL because analysis of multiple controls and clinical workup of our SPP patients excluded other factors simulating or causing a clonal T-cell proliferation. A sufficient cutaneous antitumor response but also an extracutaneous origin of the T-cell clones might explain the failure to detect skin infiltrating clonal T cells.

Demonstration of Frequent Occurrence of Clonal T Cells in the Peripheral Blood But Not in the Skin of Patients With Small Plaque Parapsoriasis

Clinical, immunohistological, and molecular biological data suggest the chronic dermatosis small plaque parapsoriasis (SPP) to be a precursor of mycosis fungoides (MF). However, most data are contradictory and confusing due to inexact definition of SPP. Recently, clonal T cells were detected in skin and blood samples of early MF. Because demonstration of identical T-cell clones in skin and blood of SPP patients would indicate a close relationship of SPP to MF, we investigated the clonality of skin and blood specimens from 14 well-defined SPP patients. By a polymerase chain reaction (PCR) amplifying T-cell receptor γ rearrangements and subsequent high-resolution electrophoresis, clonal T cells were detected in 9 of 14 initial and 32 of 49 follow-up blood samples, but in 0 of 14 initial skin specimens. Even a clone-specific PCR showing the persistence of the initial blood T-cell clone in 20 of 20 follow-up samples, failed to detect the T-cell clone in the skin. In 2 patients, the clonal T cells were shown to be CD4+. For the first time, the majority of SPP patients was shown to carry a T-cell clone in the peripheral blood. Although a relation between circulating clonal T cells and SPP cannot directly be proven by the applied techniques, our results indicate blood T-cell clonality to be a characteristic feature of SPP and CTCL because analysis of multiple controls and clinical workup of our SPP patients excluded other factors simulating or causing a clonal T-cell proliferation. A sufficient cutaneous antitumor response but also an extracutaneous origin of the T-cell clones might explain the failure to detect skin infiltrating clonal T cells.

T-cell receptor gene analysis in the diagnosis of Sézary syndrome

Diagnosing Sézary syndrome (SS) on clinicopathological grounds alone is far from straightforward, particularly in the early stages of the disease. Atypical lymphocytes may be seen in the peripheral blood of patients with reactive forms of erythroderma, so additional criteria are needed to establish the diagnosis of a T-cell leukemia/lymphoma. A wide variety of confirmatory tests have been proposed in the literature, but there has been no systematic attempt to compare the specificity and sensitivity of these different methods. Recent data indicate that T-cell receptor (TCR) gene analysis is the most useful test currently available and that methods based on polymerase chain reaction are more sensitive than Southern blot analysis. We propose that the diagnostic criteria for SS should include erythroderma, atypical circulating mononuclear cells, and evidence of a clonal T-cell population in the peripheral blood. Clonality can be established with certainty by cytogenetic or TCR gene analysis, but only the latter is sufficiently sensitive to be of value in routine diagnosis. Immunophenotypic data showing an expanded CD4(+)/CD7(-) population, an elevated CD4/CD8 ratio, or restricted V beta expression are not specific to T-cell malignancy and should not be used as a sole diagnostic criteria in SS. Entry criteria for future clinical studies will need to be more rigorous if meaningful comparisons are to be made between different treatment options.

Clonal T-cell receptor gamma-chain gene rearrangement by PCR-based GeneScan analysis in advanced cutaneous T-cell lymphoma: a critical evaluation

Detection of clonal T-cell receptor gamma (TCRgamma)-chain gene rearrangement is a promising approach to distinguish between cutaneous T-cell lymphomas (CTCLs) and reactive T-cell infiltrates. Despite the improved sensitivity by using the polymerase chain reaction (PCR) rather than Southern blot analysis, monoclonality could be demonstrated in only 53-90 per cent of CTCL biopsies in recent studies. In the present study, formalin-fixed, paraffin-embedded specimens of 21 selected patients with clear-cut advanced-stage CTCL were analysed using a semi-nested TCRgamma PCR with newly developed consensus primer pairs. Detection of PCR products was done by GeneScan analysis (GSA); this technique is advantageous due to its sensitivity and accuracy in the detection and size determination of PCR products and it is easier to interpret than direct read-outs from TGGE or DGGE gels. In serial dilution experiments, TCRgamma-PCR-GSA allowed the detection of clonal, rearranged T-cells with a high in vitro sensitivity against a polyclonal background (1-6 per cent). Despite the selection of clear-cut, advanced-stage CTCL cases, however, dominant clonal TCRgamma-chain gene rearrangement was found in only 16 of the 21 patients analysed, indicating an overall clinical sensitivity of 76 per cent. Specificity was evaluated using biopsy specimens from 21 control patients suffering from long-standing psoriasis (n=13) and eczema (n=8). Surprisingly, GeneScan profiles showing apparently single dominant peaks were detected in 14 per cent of these skin lesions, but these profiles turned out to be pseudo-monoclonal by repeated determinations. In conclusion, TCRgamma-PCR-GSA does not suffice reliably to exclude malignancy, due to its limited clinical sensitivity, but with precautions taken to detect pseudo-monoclonality and to secure specificity, TCRgamma-PCR-GSA is a valuable instrument in the diagnosis of CTCL.

Prognostic factors in Sézary syndrome: a multivariate analysis of clinical, haematological and immunological features

BACKGROUND

Sézary syndrome (SS) prognostic factors are not well defined because of the rarity of this disease. The specific goal of this prospective study was to assess by multivariate analysis the predictive value with respect to survival of a series of clinical, haematological and immunological parameters taken at SS diagnosis.

PATIENTS AND METHODS

A cohort of 62 SS patients diagnosed and followed since 1975 was examined, and 51 were included in the multivariate analysis model.

RESULTS

The median survival time was 31 months (range: 1 month-15.7+ years), and the five-year survival rate 33.5%. The following variables were found by univariate analysis to be associated with a poor prognosis at the time of SS diagnosis: previous history of mycosis fungoides (P = 0.013), high number of circulating leukocytes (P = 0.001), Sézary cells (SC) (P < 0.001) and CD4+ cells (P < 0.001), presence of large circulating SC (P < 0.001), above normal range LDH serum levels (P = 0.015), presence of PAS-positive inclusions in the cytoplasm of circulating SC (P < 0.001), high CD4/CD8 ratio (P = 0.004) and a CD7 negative circulating SC phenotype (P < 0.001). Among them, the stepwise multivariate analysis selected as adverse independent prognostic factors: PAS-positive cytoplasmic inclusions (P = 0.001), CD7 negative phenotype (P = 0.018) and presence of large circulating SC (P = 0.045).

CONCLUSIONS

Two low-/high-risk groups have been singled out on the basis of the risk index. Patients with no or one adverse prognostic feature(s) (risk index < or = 1; n = 31) share a slow disease course and a relatively favorable prognosis (five-year survival: 58%); on the other hand, patients with 2 or 3 adverse prognostic feature (risk index > 1; n = 20) are characterized by an aggressive disease course not modifiable by traditional therapies (five-year survival: 5%).

Therapy of patients with T-cell lymphomas and leukemias using an anti-CD7 monoclonal antibody-ricin A chain immunotoxin

Anti-CD7-dgA, DA7, consists of deglycosylated ricin A chain coupled to a mouse monoclonal anti-human CD7 antibody. This study determined the maximally tolerated dose (MTD) of this immunotoxin administered as a one hour infusion over five days to 11 patients with T-cell lymphoma (>30% CD7+ malignant cells). The MTD was 0.2 mg/kg/day or 1 mg/kg/120 hours (maximal toxicity grade 3) with vascular leak syndrome (VLS) as dose-limiting toxicity (DLT). Predictors of severe VLS included age and absence of circulating lymphoma cells. Two partial responses and one minimal response were seen. Patients with minimal lymphoma burden or T-cell large granular lymphocyte (LGL) leukemia showed the best responses. The mean maximal serum concentration of immunotoxin at the MTD was 2.5 ug/ml. The mean alpha-phase half-life was 1.5 hours and the mean beta-phase half-life was 8 hours. Repeated dosing had minimal effects on either peak serum immunotoxin concentrations or serum half-lives. While human antimouse antibodies were observed, they were low in concentration (<55 ng/ml). Human anti-ricin antibody was elevated in one patient (190 ng/ml). VLS presented with hypoalbuminemia, dyspnea, pulmonary edema, aphasia, and peripheral edema and cleared over a two week period. Serum fibronectin levels were measured in three patients and were very low in one patient who developed VLS. No specific binding of DA7 immunotoxin was seen with vascular endothelium in various human tissues.

Novel analysis of minimal residual disease in leukemia with TCR beta rearrangement--detection of monoclonality by single strand conformation polymorphism and PCR using a clonotype primer of leukemic T cell receptor beta-chain RNA

Several means of analyzing minimal residual disease (MRD) in leukemia involving the rearranged T cell receptor (TCR) gene have been described. We investigated MRD in leukemia with TCR beta rearrangement by examining TCR beta-chain RNA. A complementary DNA (cDNA) corresponding to the variable region of the TCR beta-chains originating from the peripheral blood or bone marrow from four patients was amplified. Single strand conformation polymorphism (SSCP) analysis of amplified cDNA showed that all four patients had monoclonal leukemia with TCR beta rearrangement; two patients had Vbeta2+ leukemia, another patient had Vbeta14+ leukemia and the other had Vbeta9+ leukemia. Flow cytometry supported this finding. Sequencing of the Vbeta2-complementarity determining region 3 (CDR3), Vbeta9-CDR3 and Vbeta14-CDR3 revealed monoclonality. To investigate MRD using TCR beta-chain RNA, cDNA from each patient was diluted with the cDNA of a healthy person and amplified using a specific CDR3 clonotype primer. A band in the ethidium bromide-stained agarose gel was detected from samples diluted 10,000-fold. SSCP analysis determined which V region gene was utilized in monoclonal leukemic cells. The leukemic cell specific TCR, determined in such a manner, may be a target for immunotherapy. Because the MRD of T cell malignancy can be easily examined once the CDR3 clonotype primer is made, this novel analysis is considered to be a useful method.

Photopheresis therapy for cutaneous T-cell lymphoma

BACKGROUND

Cutaneous T-cell lymphoma is a chronic peripheral lymphoma in which aggressive combined therapy elicits high response rates but does not improve survival. Photopheresis therapy has reportedly induced remissions and prolonged survival in patients with advanced disease.

OBJECTIVE

We studied all patients who began photopheresis treatment between February 1988 and July 1994 to determine whether we could confirm the remission rates of previous studies, to evaluate variables that might predict a response, and to discover whether an accelerated delivery system would improve the remission rate or response time.

METHODS

After an oral dose of methoxsalen was administered, a leukocyte-enhanced quantity of blood was exposed to UVA radiation for 1.5 hours and returned to the patient. With our accelerated system, 6 x 10(9) cells were irradiated in nine cycles. Treatments were given on 2 consecutive days once a month.

RESULTS

Among 34 patients whose results could be evaluated, the overall response rate (complete and partial remissions) was 50%; most patients had mild side effects. All responders except one had erythroderma. Responders had a decrease of 75% in mean skin scores, whereas nonresponders had an increase of 21%.

CONCLUSION

Photopheresis appears to be effective for selected patients with erythrodermic cutaneous T-cell lymphoma, although we did not achieve as high a remission rate as previously reported by others.

Unusual and unrelated polyclonality in a case of myeloid disease

A case of myelofibrosis with myeloid metaplasia was found to have five cytogenetically unrelated clones in the marrow, four of these clones being abnormal. We present the hypothesis that the hematologic disease in this patient was caused by a genetic event not discernible microscopically (cytogenetically) and that the distinctive abnormal clones may have been generated at different anatomic sites.

VJ rearrangements of the TCR gamma locus in peripheral T-cell lymphomas: analysis by polymerase chain reaction and denaturing gradient gel electrophoresis

Using Southern blotting for the diagnosis of clonality in peripheral T-cell lymphomas (PTCLs), analysis of the T-cell receptor (TCR) gamma gene rearrangement was shown to be more informative than that of the TCR beta gene rearrangement. In order to amplify every VJ gamma rearrangement, a polymerase chain reaction (PCR) procedure using newly designed GC-clamp primers has been developed. All primers can be mixed in a single multiplex PCR. PCR products are analysed by denaturing gradient gel electrophoresis (DGGE), providing tumour-specific imprints inasmuch as the procedure characterizes N sequence polymorphism at the VJ junctions. In a series of 30 PTCL cases, the PCR procedure demonstrated 27 cases to be clonally rearranged and failed in three cases. PCR was more accurate than Southern blotting, showing 47 rearranged gamma alleles, four of which were undetectable on the Southern blot. When lymphomas were studied at different sites and at relapse, the DGGE pattern remained unchanged. In PTCL, the proposed PCR is helpful for the diagnosis and staging of the disease and should improve the follow-up monitoring. The undetectability of clonal rearrangements in a few cases is discussed in the light of concepts of lymphomagenesis and T-cell differentiation.

Molecular genetics and lymphoproliferative disorders

Clonality of T- and B-cell lymphoproliferative disorders can be determined by gene rearrangement studies when morphology and surface immunostaining are nondiagnostic. TcR and lg gene rearrangements have been demonstrated in many different hematologic disorders and TcR gene rearrangement has been particularly useful in the diagnosis of patients with CD8 large granular lymphocyte leukemias. TcR gene rearrangement may also be useful to distinguish Hodgkin's disease from T-cell non-Hodgkin's lymphoma. Gene rearrangement is usually performed by Southern analysis, and it is beneficial to run multiple enzyme-probe combinations to maximize the detection of clonal rearrangements. More recently, several laboratories have begun to use polymerase chain reaction (PCR) for gene rearrangement analysis. PCR offers an improved turnaround time, eliminates partial digestion artifacts, and allows for the use of paraffin embedded material. In addition to rearrangements of the TcR and lg genes, analysis of alterations in other genes such as bcl-1, bcl-2, bcl-6, and c-myc are also useful as clonal markers and aid in the classification of lymphomas.

Pulmonary involvement in lymphoma

Intrathoracic involvement is common in both Hodgkin's disease (HD) and non-Hodgkin's lymphoma (NHL). The most common manifestation is mediastinal lymphadenopathy. In HD, nodal involvement is by contiguity and usually involves the superior mediastinum, while the findings in NHL are more variable. Pulmonary parenchymal disease occurs in 38% of HD and 24% of NHL. In untreated HD, parenchymal involvement is invariably associated with mediastinal lymphadenopathy and often with widespread disease. Three distinct radiological patterns of pulmonary lymphoma are recognised: nodular, bronchovascular-lymphangitic and pneumonic-alveolar. Rarely lymphoma may be endobronchial. Pleural effusion occurs in 16% of lymphoma patients and is usually associated with disease elsewhere. It is frequently caused by lymphatic obstruction but may be due to direct pleural involvement by tumour. Chylothorax may occur in NHL but is unusual in HD. Diagnosis of intrathoracic lymphoma is by transbronchial or transthoracic biopsy or by needle aspiration of tissue or pleural fluid. The addition of immunostaining improves the diagnostic yield in equivocal cases. Treatment and prognosis vary depending on cell-type, location and extent of disease.

T-cell lymphoma cell lines (HUT102 and HUT78) established at the National Cancer Institute: history and importance to understanding the biology, clinical features, and therapy of cutaneous T-cell lymphomas (CTCL) and adult T-cell leukemia-lymphomas (ATLL)

Efforts at the National Cancer Institute to generate continuous in vitro cultures from patients with mycosis fungoides and the Sezary syndrome, neoplasms with a mature T-helper phenotype, led to the establishment of two cell lines, HUT78 and HUT102. Further characterization of these cell lines led to the identification of the first human retrovirus, HTLV-1, in the HUT102 cells, and the clinical description of the syndrome of HTLV-1 associated acute T-cell leukemia/lymphoma; the serum antibody test to screen for this virus was developed from the serum of the patient from whom the cell line was derived. The HUT78 cell line was pivotal in the identification and characterization of the HIV retrovirus in that a subclone, H9, proved to be permissive for replication of HIV in vitro. Propagation of HIV in vitro in H9 cells allowed for the development of immunological reagents to screen blood supplies for the presence of the virus. Further biologic and molecular studies of these lines have led not only to a better understanding of the underlying diseases but also to the development of rational therapeutic approaches.

The polymerase chain reaction in the demonstration of monoclonality in T cell lymphomas

AIMS

To evaluate polymerase chain reaction (PCR) amplification of T cell receptor (TCR) beta and gamma chain genes as a means of demonstrating monoclonality in T cell lymphomas using histological samples; to compare the performance of PCR with Southern blot analysis.

METHODS

TCR-beta, TCR-gamma and immunoglobulin heavy chain (IGH) genes were analysed using PCR in 55 cases of T cell lymphoma (28 frozen tissue and 27 paraffin wax embedded samples), diagnosed using morphological and immunohistochemical criteria. The 28 frozen samples were subjected to Southern blot analysis using TCR-beta, TCR-gamma and IGH gene probes. Twenty five B cell lymphomas and 21 non-neoplastic lymphoid tissue samples were used as controls.

RESULTS

Using TCR-beta PCR, monoclonality was detected in 24 (44%) of 55 T cell lymphomas compared with 43 (78%) of 55 using TCR-gamma PCR and in 82% with both techniques. Five (9%) of 55 T cell lymphomas were IGH PCR positive. None of the non-neoplastic lymphoid control samples were PCR positive. All B cell lymphomas showed a polyclonal pattern with TCR-beta PCR while a single B cell lymphoma was positive using TCR-gamma primers. With TCR-beta PCR, a monoclonal result was seen in 12 (43%) of 28 frozen samples of T cell lymphoma, compared with 23 (82%) of 28 using Southern blot analysis. With TCR-gamma PCR, 19 (68%) of 28 frozen tissue samples were positive, compared with 26 (93%) of 28 using Southern blot analysis. A single case showed IGH rearrangement by Southern blot analysis.

CONCLUSION

TCR-gamma PCR should be the method of choice for analysis of clonality in paraffin wax embedded sections of lymphoproliferative lesions, as TCR-beta PCR has a high false negative rate. Southern blot analysis remains the most successful technique when sufficient fresh tissue samples and resources are available.

Gene rearrangement in positive patch tests

Lymphoproliferative disorders are usually characterized by lymphoid infiltrates that demonstrate clonality in contrast to inflammatory or reactive infiltrates of the skin that are polyclonal without detectable monoclonal populations of T-cells. Probably the southern blot analysis of TCR gene rearrangement can help to delineate the reactive from the malignant processes. In this study, we applied the technique on benign reactive processes in the skin. We examined biopsies from positive patch tests from patients with a delayed hypersensitivity reaction. We found the same gene rearrangement configuration in 11 of 17 patients with positive patch tests. The extra band revealed in these cases was situated in the EcoR1 digested DNA lane at the 8.0 Kb, between the 2 germline bands at the 11 Kb and the 4 Kb respectively. This observation was not correlated to the degree of the inflammatory response or to the specific hapten induced reaction. This pattern was not found in any of 107 patients with malignant diagnoses, but also in six of 43 patients with benign diseases. The clinical implication may suggest the presence or development of clonality in benign inflammatory disorders.

A clinical and histologic mycosis fungoides simulant occurring as a T-cell infiltrate coexisting with B-cell leukemia cutis

One year after the onset of chronic lymphocytic leukemia, an elderly man had scaly cutaneous plaques on the thighs that clinically and histologically resembled the mycosis fungoides type of cutaneous T-cell lymphoma. Two years later the patient had indurated, red dermal nodules on the face that clinically and histologically were characteristic of cutaneous chronic lymphocytic leukemia. Immunophenotyping results from a facial nodule confirmed the presence of a B-cell infiltrate (CD20+). Immunophenotyping of a lesion on the right thigh showed that half the cells were composed of a CD2+, CD45RO+ (UCHL-1+) upper dermal and focally epidermotropic population of T cells consistent with mycosis fungoides; however, these T cells coexisted with an equal number of CD20+ B cells arranged in distinct clusters. DNA from the thigh lesion exhibited a B-cell immunoglobulin gene rearrangement, but the T-cell receptor gene rearrangements were germline. In this case, the evidence favors a mycosis fungoides simulant occurring as a reactive T-cell infiltrate to an underlying B-cell chronic lymphocytic leukemia.

T cell receptor usage in autoimmune disease

Activated T-cells are believed to play a critical role in the pathogenesis of autoimmune disease. In experimental allergic encephalomyelitis (EAE), an animal model resembling human multiple sclerosis (MS), there is evidence that T cells reactive to myelin basic protein mediate an inflammatory response within the central nervous system leading to demyelination. Furthermore, encephalitogenic T cells express TCR with highly restricted V gene usage and consequently specific forms of immunotherapy directed against V gene products have been successful in preventing and treating EAE. These findings prompted studies into the analysis of TCR repertoire expression in human autoimmune diseases in an attempt to identify the TCR usage of autoreactive and potentially pathogenic T cells. However, this has proved difficult as the autoantigens that drive the T cell response in most human autoimmune disorders are unknown. This review examines the data that have accumulated over the past few years on TCR usage in human autoimmune diseases and is focused largely on rheumatoid arthritis and MS.