Chromosome abnormalities in peripheral T-cell lymphoma

Molecular and Genomic Landscape of Peripheral T-Cell Lymphoma

Peripheral T-cell lymphoma (PTCL) is an uncommon group of lymphoma covering a diverse spectrum of entities. Little was known regarding the molecular and genomic landscapes of these diseases until recently but the knowledge is still quite spotty with many rarer types of PTCL remain largely unexplored. In this chapter, the recent findings from gene expression profiling (GEP) studies, including profiling data on microRNA, where available, will be presented with emphasis on the implication on molecular diagnosis, prognostication, and the identification of new entities (PTCL-GATA3 and PTCL-TBX21) in the PTCL-NOS group. Recent studies using next-generation sequencing have unraveled the mutational landscape in a number of PTCL entities leading to a marked improvement in the understanding of their pathogenesis and biology. While many mutations are shared among PTCL entities, the frequency varies and certain mutations are quite unique to a specific entity. For example, TET2 is often mutated but this is particularly frequent (70-80%) in angioimmunoblastic T-cell lymphoma (AITL) and IDH2 R172 mutations appear to be unique for AITL. In general, chromatin modifiers and molecular components in the CD28/T-cell receptor signaling pathways are frequently mutated. The major findings will be summarized in this chapter correlating with GEP data and clinical features where appropriate. The mutational landscape of cutaneous T-cell lymphoma, specifically on mycosis fungoides and Sezary syndrome, will also be discussed.

'Normal counterparts' of nodal peripheral T-cell lymphoma

Peripheral T-cell lymphomas (PTCL) have been difficult to classify. A homogeneous principle of classification is still lacking, partly because lymph node compartments containing functionally distinct T-cell subsets have not been identified. A correlation to differentiated T-cell subsets, as CD4(+) or CD8(+) cells as well as cytotoxic populations has not revealed clinically meaningful entities. Upon antigen encounter, mature T-cells pass through distinct stages characterized by their surface molecule expression. Naïve T-cells are CD45RA(+)/CD45R0(-)/CD27(+)/CCR7(+), however, after antigen contact CD45RA expression is replaced by CD45R0. They differentiate to central memory cells, which retain CD27 and CCR7, or to effector-memory cells, which loose expression of both molecules depending on the strength of the antigen interaction. Immunohistological analysis of PTCL showed an effector or effector-memory cell phenotype (CD45RA(-)/CD45R0(+)/CD27(-)) for both angioimmunoblastic T-cell lymphoma (AILT) and anaplastic large cell lymphoma (ALCL), but different cytotoxic and activation markers expressed by these tumours. A subset of CD4(+) PTCL-not otherwise specified (PTCL-NOS) may correspond to a central memory cell phenotype (CD45RA(-)/CD45R0(+)/CD27(+)). Thus, a correlation of PTCL to stages of differentiation, rather than to the direction of differentiation, may reveal homogeneous categories. A comparison between the lymphomas and their normal counterparts may contribute to the understanding of the underlying transformation mechanisms.

Identification of the tumor cells in peripheral T-cell lymphomas by combined polymerase chain reaction-based T-cell receptor beta spectrotyping and immunohistological detection with T-cell receptor beta chain variable region segment-specific antibodies

Most nodal peripheral T-cell lymphomas (PTCL) originate from alphabeta-T cells, and they often contain reactive T cells that may hamper immunophenotyping. To specifically identify the neoplastic population in immunohistochemically stained slides, we assessed the heterogeneity of the T-cell receptor beta chain variable region (TCRVbeta). This region contains 65 gene segments, of which only one is expressed after rearrangement. To investigate PTCL, we developed a polymerase chain reaction assay to define the clonally rearranged TCRVbeta segment. Detecting the corresponding epitope with segment-specific antibodies enabled identification of tumor cells among the T cells. The TCRVbeta segment of the tumor cells was defined in 13 of 13 PTCL not otherwise specified and 11 of 13 angioimmunoblastic T-cell lymphomas. Antibodies corresponding to the respective TCRVbeta segment of the tumor were available for seven cases from each group. After applying these antibodies in combination with antibodies against CD3, CD5, CD4, CD8, and cytotoxic molecules, double stains were evaluated by confocal laser scanning microscopy. In 9 of 14 cases, less than 50% of T cells expressed the clonally rearranged TCRVbeta segment. Phenotypes defined in double stains differed from those obtained by conventional immunohistochemistry in 11 of 14 cases. The combination of TCRVbeta polymerase chain reaction and immunohistochemistry may facilitate more reliable detection and characterization of tumor cells in PTCL.

Chromosomal abnormalities of 200 Chinese patients with non-Hodgkin's lymphoma in Taiwan: with special reference to T-cell lymphoma

BACKGROUND

The distribution of the histopathological subtypes of non-Hodgkin's lymphoma (NHL) is different among various geographical areas. However, there are few reports concerning cytogenetic findings of NHL, especially T-cell lymphoma, in Asian people.

PATIENTS AND METHODS

We analyzed the chromosomal abnormalities of 200 adult patients with NHL in Taiwan and correlated the non-random aberrations with the histological subtypes.

RESULTS

One hundred and thirty-eight patients (69%) had B-cell lymphoma. The incidence of the t(14;18) in total lymphoma was lower in Taiwan (12%) than in the West (20-30%), but its incidence in follicular lymphoma was comparable between the two areas (17 of 28 patients, 61% versus approximately 50-60%). Sixty-two patients (31%) had T-cell lymphoma, including 11 angiocentric T/natural killer (NK)-cell lymphoma and only two angioimmunoblastic T-cell lymphoma (AILD). The recurrent chromosomal abnormalities in T-cell lymphoma comprised 6q deletion (30%), 11q deletion (20%), 17p deletion (16%), -17 (16%), -Y (14%) and + 8 (11%). Angiocentric T/NK-cell lymphoma had a significantly higher frequency of 1q duplication (P=0.001), 6p duplication (P <0.001) and 11q deletion (P=0.011) than other T-cell lymphoma. The incidences of +3 and +5, two common abnormalities in AILD, were quite low in T-cell lymphoma in Taiwan (4% and 2%, respectively), compared with those in the West (16-32% and approximately 15%, respectively). The 11q deletion, not a common aberration in T-cell lymphoma in western countries, occurred quite frequently in Taiwan.

CONCLUSIONS

The chromosomal aberrations of NHL are quite different among various geographical areas, which may reflect the differences in the distribution of the histological subtypes of lymphoma among various areas.

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.

Angioimmunoblastic T cell lymphoma is derived from mature T-helper cells with varying expression and loss of detectable CD4

Angioimmunoblastic T cell lymphoma (AILT) is a rare lymphoma that is regarded as a clinicopathologic entity but shows considerable histomorphologic diversity, variable immunophenotypes and inconsistent T cell receptor (TCR) gene rearrangement. One hundred four paraffin blocks of AILT were investigated defining tumor cell lineage by triple immunostains with a confocal laser scanning microscope and correlating morphology, immunophenotype and TCRgamma gene rearrangement to clinical outcome. Ninety-nine cases were CD4(+), some of them showing a mixture of CD4(+) and CD4(-) tumor cells. The remaining 5 specimens were CD3(+)/CD4(-)/CD8(-). A considerable number of T cells of different subtypes could always be found, but even in 13 cases predominated by CD8(+) cells, proliferation could be attributed to atypical CD4(+) cells. TCRgamma gene rearrangement was monoclonal in 48 cases (69%) among 70 tested. In 29 of these semi-quantitative gene scan analysis resulted in a median proportion of monoclonal peak of 35% of PCR-products. Clinical outcome was identical grouping patients by clonality of TCRgamma, absence or presence of clear cell clusters and international prognostic index. We conclude that AILT is mainly derived from CD2(+)CD3(+)CD4(+)CD5(+)CD7(-) mature T-helper cells with varying expression and partial loss of detectable CD4. A significant number of non-neoplastic T cells (resting CD4(+) T cells and activated small or medium-sized CD8(+) lymphocytes) may coexist with a minor neoplastic T cell population. Clinicopathologic correlation suggests AILT to be a well defined homogeneous entity with poor prognosis. Currently no prognostic factors can be derived.

T-zone lymphoma with cutaneous involvement: a case report and review of the literature

T-zone lymphoma (TZL) is a rare subtype of nodal peripheral T-cell lymphoma characterized by a clonal expansion of T-zone lymphocytes accompanied by a proliferation of other T-zone constituents. Non-specific cutaneous alterations are seen in about one-third of all cases, but specific cutaneous involvement is extremely rare. We present a case of TZL with secondary skin infiltration, review the literature on cutaneous manifestations of TZL and discuss the differential diagnosis of TZL.

Chromosome abnormalities in peripheral T-cell lymphoma

Data on chromosomal abnormalities in T-cell lymphomas are very rare as compared with those reported in B-cell lymphomas. We performed a cytogenetic study in 71 untreated patients with peripheral T-cell lymphoma, classified according to the criteria of the REAL classification. Fifty-seven patients (80.3%) had abnormal clones, whereas 9 karyotypes (12.7%) showed only normal metaphases; 5 karyotypes (7%) could not be analyzed. Recurrent numerical chromosomal abnormalities comprised +3 (21%), +5 (15.7%), +7 (15.5%), +21 (14%), -13 (14%), +8 (12.2%), +19 (12.2%), -10 (10.5%), and -Y (9% of male patients). Chromosomes involved in structural rearrangements were chromosome 6 (31.5%), mainly due to 6q deletions (19.2%), 1q (22.8%), 7q (22.8%), 9p (19.4%), 9q (19.2%), 4q (19.2%), 3q (19.2%), 2p (17.5%), 1p (17.5%), and 14q (17%). Trisomies 3 and 5 mainly correlated with angioimmunoblastic T-cell lymphoma. Isochromosome 7q, associated with trisomy 8, was present in two cases of hepatosplenic gamma/delta T-cell lymphoma. Rearrangements involving the location of T-cell receptor genes were rarely observed (chromosome band 7q35 was rearranged only in three cases, 14q11 in two cases, and 7p15 in none). No correlation could be found between the cytogenetic findings and histologic subgroup or clinical outcome in these patients. Further studies are needed to understand the significance of these abnormalities in peripheral T-cell lymphoma, and to reach a better evaluation of histologic correlations, as many differences persist between the two major classification systems, KIEL and REAL.

Unbalanced X;autosome translocation (X;18)(q13;p11) in a case of aggressive natural killer non-Hodgkin lymphoma

Recent evidence has shown that rare cases of aggressive non-Hodgkin lymphomas (NHL) derive from cells belonging to the natural killer (NK) lymphocyte lineage and a new clinico pathologic entity has been proposed. Though well documented in B- and T-cell NHL, chromosome abnormalities are rare findings in NK-NHL and to date, no recurrent cytogenetic abnormality has been described. The present study reports the clinical data, cytogenetic and fluorescence in situ hybridization (FISH) analysis of a new case of typical NK-NHL characterized by a primary unbalanced translocation (X;18) (q13;p11). Recent data of X;autosome translocation in malignant lymphomas have proposed Xp22 and Xq28 as the location of NHL-related oncogenes. According to other published reports on the involvement of the Xq13 region in NHL and particularly in aggressive forms, we hypothesize the existence of additional putative lymphoma-associated oncogenes at the band Xq13.

Gene rearrangements and chromosomal translocations in T cell lymphoma--diagnostic applications and their limits

The diversity of the T cell receptor (TCR) repertoire is established for individual T lymphocytes by developmentally regulated gene rearrangements and shaped by predominantly intrathymic selection procedures. TCR gene probes in Southern blot experiments and TCR primers for the polymerase chain reaction (PCR) help to distinguish polyclonal from abnormal clonal T cell proliferations and to monitor clonal disease after treatment. Rearrangement studies can identify the lineage and developmental stage of a lymphocyte clone. Cross-lineage rearrangements, false positive or negative results are rarely misleading when morphology and immunophenotypical findings are considered. Rearrangement studies, however, have not contributed significantly to the comprehension of lymphomagenesis. Analyses of characteristic chromosomal translocations in T cell leukaemias and lymphomas may provide further insight into the mechanisms of malignant transformation. Transcription factors are often involved and sometimes abnormally transcribed, which may alter the physiological intracellular signalling in T cells. Interphase cytogenetic analysis by chromosomal fluorescence in situ hybridization (FISH) has become a new tool in the search for transformed T cells carrying specific translocations. Archival biopsy material is now accessible for PCR rearrangement studies and FISH cytogenetics. This adds another dimension to the diagnosis, disease monitoring and biological understanding of malignant T cell lymphomas and leukaemias.

Two novel human B-cell lymphoma lines of lymphatic follicle origin: cytogenetic, molecular genetic and histopathological characterisation

Two B-cell lines, designated as HF-1 and HF-4, were characterised. The cell lines have complicated karyotype abnormalities including a 14;18 translocation and an 8q24 breakpoint originating from t(2;8)(p11;q24) (HF-1) or t(1;8)(p21;q24) (HF-4). The lines have BCL2 rearrangement and they are positive for CD19, CD20, CD22, CD39. HF-1 is also positive for IgG, and HF-4 is positive for IgM and IgD. On Northern blot analyses, the 2.6-kb and 4.2-kb transcripts corresponding to the major transcripts of CMYC and BCL2, respectively, were seen. In Western blot as well as in FACS (fluorescence-activated cell sorting) analysis the presence of BCL2 protein in the both HF-1 and HF-4 cells was demonstrated. The cell lines are expected to serve as an important tool in the study of the chromosomal mechanism activating cellular oncogenes, the somatic hypermutation mechanism of antigen-activated B cells and the apoptosis of B cells.

Cytogenetic characterization of Epstein-Barr virus-associated T-cell malignancies

Recently, Epstein-Barr virus (EBV) infection has been found not only to be associated with Burkitt lymphoma and nasopharyngeal carcinoma but also with some T-cell malignancies. Cytogenetic studies were performed on four Chinese patients with EBV-associated T-cell neoplasms: three peripheral T-cell lymphomas and one large granular lymphocyte leukemia with coexpression of T-cell antigen. Clonal chromosomal abnormalities were detected in all four patients. Rearrangements of chromosome 7 were observed in three patients: one at 7p22, one at 7q35 or 36, and the remaining one at both sites. The last patient also had a chromosomal abnormality involving 14q11. Trisomy of part of the 1q segment was detected in two patients. The results revealed that the chromosomal abnormalities in these patients were similar to those observed in other T-cell lymphomas. Further studies on more patients are necessary to find out whether there are specific chromosomal aberrations in EBV-associated T-cell neoplasms.

Unusual presentation of extranodal peripheral T-cell lymphomas with multiple paraneoplastic features

Three patients with extranodal peripheral T-cell lymphoma and a distinctive clinical presentation are described. They had acute onset of fever, weight loss, progressive liver failure, bleeding diathesis, pancytopenia, and myelodysplastic changes in the bone marrow. Each patient had one or more paraneoplastic complications: severe rhabdomyolysis with myoglobinuria and secondary renal failure, cutaneous vasculitis, gluten-sensitive enteropathy, polyserositis, and increased macrophages with hemophagocytic activity. They did not have peripheral lymphadenopathy. The complex clinical presentations simulated collagen vascular disorders, systemic infections, or severe liver disease rather than a malignant lymphoma. Routine histologic studies revealed a small population of lymphoma cells in the bone marrow, spleen, and liver. Immunophenotyping studies demonstrated their T-cell phenotype, and cytogenetic analysis showed the clonality in Patients 1 and 2; clonal T-cell receptor gene rearrangement was found in Patients 2 and 3. These studies should be considered in the evaluation of patients with constitutional symptoms, liver failure, coagulopathy, and pancytopenia even in the absence of peripheral lymphadenopathy.

Stepwise development of chromosomal abnormalities in angioimmunoblastic lymphadenopathy

Cytogenetic studies of lymphoproliferative diseases, such as angioimmunoblastic lymphadenopathy (AILD), may provide a clue to the understanding of tumor development. Angioimmunoblastic lymphadenopathy may evolve from a nonmalignant lymphoproliferation into a peripheral T-cell lymphoma or even into a high-grade B-cell lymphoma and thus offers the chance to observe cytogenetic changes during lymphoma development. We report the cytogenetic findings in 24 cases of AILD. They are discussed together with 18 previously published cases from the same series. A striking feature was that unrelated chromosome abnormalities, both clonal and nonclonal, were frequently observed. Eighteen of 25 cases with aberrant clones show trisomy 3 (a characteristic chromosome abnormality in peripheral T-cell lymphoma), trisomy 5, or both. This finding provides cytogenetic evidence that these cases are definitely peripheral T-cell lymphomas. From the results of the 42 cases, hypotheses of stepwise evolution of the chromosome abnormalities in AILD are deduced: the first step is the appearance of chromosome abnormalities in different cells because of a genetic instability. At this time, clonal proliferation of T cells was already demonstrated by the rearrangement of T-cell receptor genes. As a second step, chromosomally aberrant clones become established. A cytogenetically detectable monoclonal proliferation represents the third step.

1p13 is the most frequently involved band in structural chromosomal rearrangements in human breast cancer

Cytogenetic data on 14 breast carcinomas were examined to determine which chromosome arms and bands are preferentially involved in structural chromosome changes. Chromosome arms 17p, 16q, and 1p and band 1p13 were found to be significantly involved. A review of the world literature confirmed 1p as being the most frequently involved arm in structural chromosome changes in breast cancer and 1p13 as being the band most frequently involved in such changes. The two sets of results were pooled, and the analysis of 113 tumours revealed 229 of 304 bands to be involved, with 1p13 affected in 20% of the tumours.

Cytogenetic findings in 21 cases of peripheral T-cell lymphoma

Although numerous publications have described the chromosome abnormalities in B-cell non-Hodgkin lymphoma and their significance, sparse literature exists pertaining to the chromosome abnormalities in T-cell lymphoma. We did cytogenetic analyses in 21 cases of peripheral T-cell lymphoma (PTCL). Chromosomally abnormal clones were identified in 15 (71%) of the cases, including 7 of the 10 cases in which the histologic distinction between a malignant and benign process was difficult. Abnormalities of chromosome 1 were observed in 10 cases; a breakpoint at 1p36 was demonstrated in 5 of these cases. Chromosome abnormalities previously attributed to B-cell malignancies were infrequent. These results suggest an association between 1p36 breakpoints and PTCL and emphasize the utility of cytogenetic analysis for documenting clonality among the histologically diverse groupings of PTCL.

Recurrent chromosomal aberrations in peripheral T-cell lymphoma

Histological, immunological, and cytogenetic analysis of the same neoplastic tissues have been performed on seven patients with peripheral T-cell lymphomas (PTCL). Clonal chromosomal abnormalities in five cases are reported. The most common chromosomal aberration, observed in four patients, is a rearrangement of chromosome 14 with a breakpoint in q11.2. Aberrations of chromosome 8 also occurred in four patients, three of whom had an extra 8q. The data indicate that breakpoints of malignant diseases affecting similar cell types might cluster to specific chromosomal regions, which can be helpful in recognition and classification of PTCL.

Immunohistochemical, molecular, and cytogenetic analysis of a consecutive series of 20 peripheral T-cell lymphomas and lymphomas of uncertain lineage, including 12 Ki-1 positive lymphomas

Although several independent series of non-Hodgkin's lymphomas (NHLs) have been subjected to cytogenetic studies or analyses of lineages by assaying for clonal immunophenotypes and clonal rearrangements affecting immunoglobulin (IG) and T-cell receptor (TCR) genes, no published reports exist of series of non-B-cell NHLs on which cytogenetic, immunohistochemical, and IG and TCR gene rearrangement studies have been undertaken together. Among 343 NHLs ascertained prospectively between January 1984 and December 1988 at the Memorial Sloan-Kettering Cancer Center, 278 cases with clonal chromosome abnormalities were identified. Of the latter, 20 were non-B-cell NHLs, which in turn comprised 15 peripheral T-cell lymphomas (PTCLs) and 5 lymphomas of uncertain lineage (LULs). The LULs either were biogenotypic, had discordant immunophenotype and immunogenotype, or showed no evidence of B-cell, T-cell, or histiocytic derivation. Of the 15 PTCLs, eight expressed the Ki-1 antigen and four of these had translocations involving the band 5q35 [t(5q35)]. Of the five LULs, four expressed the Ki-1 antigen and one of these had a translocation involving band 5q35. Previous studies have associated t(5q35) with Ki-1 positive NHLs characterized histologically by a pleomorphic diffuse large cell morphology. In our series of 12 Ki-positive non-B-cell NHLs, five (42%) had a 5q35 translocation. They were histologically indistinguishable from the subset without the translocation. The frequent lineage uncertainty exhibited by Ki-1 positive NHLs of similar histology and cytogenetic abnormalities suggests their derivation from an early uncommitted lymphoid cells.

Chromosomal abnormalities in patients with non-cutaneous T-cell non-Hodgkin's lymphoma. The Nebraska Lymphoma Study Group

In contrast to non-Hodgkin's lymphomas (NHL) with a B-cell phenotype, almost no data have been reported dealing with correlations between chromosomal abnormalities and characteristics of the disease in patients with T-cell NHL. In a retrospective analysis we studied all patients with a non-cutaneous T-cell NHL and chromosomal abnormalities that were evaluated at our institution; 20 patients could be identified. Numerical abnormalities involving chromosomes 3, 4, 5, 22 and X were observed most frequently. Structural abnormalities involved mainly the breakpoints 1q22-25, 6q23 and 11q13. There appeared to be an association between +7, breakpoints 2p23-24, 4p14-15, 8q21 and the presence of extranodal disease. All patients with +7 had a diffuse mixed histology. Patients with +2, +3, +11, +17, +18, +20 or breakpoint 1q22-25 had an immunoblastic lymphoma and patients with breakpoints 9q32-34 or 14q12 had a lymphoblastic lymphoma. No correlations were observed between chromosomal abnormalities and response to therapy, survival or phenotypic markers. Abnormalities involving the chromosomes containing the T-cell receptor genes and T-cell markers were infrequent. Several breakpoints were identified that correlate with already described oncogenes.

Abnormalities of chromosome 1 in relation to human malignant diseases

Chromosome 1 is known to often be involved in various malignant diseases. Its numerical and structural aberrations have been observed in chronic and acute leukemias and solid tumors as well. Recently five protooncogenes have been assigned to the long and short arms of chromosome 1. The frequent and nonspecific occurrence of chromosome 1 rearrangements in human tumors suggests that they play an important role in the pathogenesis and progression of these diseases. The frequency, types, and time of the occurrence of chromosome 1 aberrations and their relation to the stage of the disease were studied in 317 patients with various malignant diseases. In ten patients nonrandom aberrations of chromosome 1 were observed. Two patients had CML, two PRV followed by ANLL, and the remaining six patients suffered from ANLL, ALL, Burkitt lymphoma, MF, SMMoL, and IRSA, respectively. In six patients, total or partial trisomy of the long arm or of the whole chromosome 1 was present, and in three cases balanced translocations involving chromosome 1 could be found. In the cells of one patient a duplication of the centromeric heterochromatin was seen. We analyzed the breakpoints involved. Finally, the aberrations of chromosome 1 were almost always be observed at the terminal stage of the diseases.

The gene for human thioredoxin maps on the short arm of chromosome 3 at bands 3p11-p12

Thioredoxin, a ubiquitous enzyme possessing an oxidoreductase activity, has recently been cloned in human. Using in situ chromosomal hybridization with a human thioredoxin cDNA probe, we have precisely localized the thioredoxin gene on chromosome 3 at bands 3p11-p12.

Characterization of neoplastic and reactive cells in T-cell lymphomas with cytogenetic, surface marker, and DNA methods

Three patients with T-cell lymphoma were studied with a combined cytogenetic-immunological analysis (MAC) as well as by Southern blotting analysis. The MAC method, which allows simultaneous study of both chromosomes and immunophenotype of a mitotic cell, revealed that in each case the karyotypically abnormal and, therefore, neoplastic cells originated from different stages of T-cell maturation. In one case the abnormality was seen in cells expressing CD3 and CD10, in the second in cells expressing CD3 and CD8, and in the third case in cells expressing CD4 but not CD3. Mitoses were frequent also in non-neoplastic cells, but these mitoses were normal. Southern blotting analysis revealed TCR beta rearrangements in all patients. In addition, one patient displayed TCR gamma rearrangement, and one patient a rearrangement in the IgH joining region.

Cytogenetics of T-cell malignant lymphoma. Report of 17 cases and review of the chromosomal breakpoints

Cytogenetic studies are reported on 17 T-cell malignant lymphomas (ML) including six cutaneous T-cell malignant lymphomas (CTCL). Due to the low incidence of rearrangements on bands where the T-cell receptor genes are located, other cases reported in the literature were analyzed in order to estimate the most frequent chromosomal breakpoints in ML, CTCL, and adult T-cell leukemia-lymphoma. Besides chromosomes 1 and 6q, 14q11, 7p15p21, and 7q32q35, the most frequent rearrangements involved bands 14q32, 2p11-p14, 2p23-p25, 17cen, 9p21p23, and 10p13p15. These results show that molecular studies must be concentrated on these chromosomal regions in order to identify the DNA sequences that may be involved in T-cell malignancies.

Nonrandom chromosomal abnormalities in malignant pleural mesothelioma

Cytogenetic studies were performed on tumor cells from specimens of 30 consecutive patients with malignant pleural mesothelioma. Metaphases for chromosomal G-banding analyses were obtained from 27 of these patients. Clonal abnormalities were detected in 19 patients. Karyotype findings were complex and heterogeneous: aneuploidy, polyploidy, structural abnormalities, and several subclones were seen. The most frequent chromosomal abnormalities were polysomy or partial polysomy 7, monosomy or partial monosomy 22, and rearrangements involving breakpoints at 1p11-22.