Gamma/delta T-cell lymphoma with mycosis fungoides-like clinical course transforming to "T-cell-receptor-silent" aggressive lymphoma: Description of one case.

Primary cutaneous γδ T-cell lymphomas (PCGDTLs) are a heterogeneous group of lymphomas representing about 1% of primary cutaneous T-cell lymphomas (CTCLs) and mostly regarded as clinically aggressive. Current WHO-EORTC classification recognizes different clinic-pathologic subsets of PCGDTL, but it suggests that cases showing a mycosis fungoides (MF)-like clinical presentation and histopathology should be classified as MF irrespective of phenotype for their indolent course. Herein, we describe a case of γδ-MF, featuring at onset a granulomatous pattern, with subsequent clinical worsening signaled by the development of an ulcero-necrotic lesion and systemic dissemination, leading to death in 5 months. Clinical progression was sustained by a shift to mature T-cell lymphoma composed of medium to large-sized blastoid T-cells featuring a T-cell receptor (TCR) silent immunophenotype.

Lymphomatoid papulosis types D and E: a multicentre series of the French Cutaneous Lymphomas Study Group.

BACKGROUND: Lymphomatoid papulosis (LyP) type D (LyP D) and type E (LyP E) have recently been described in small series of cases or isolated case reports. AIM: To further describe the clinical and histological features of LyP D and E based on a retrospective multicentre study. METHODS: The clinical and histopathological features of 29 patients with an initial diagnosis of LyP D or LyP E were retrospectively assessed using standardized forms. RESULTS: After exclusion of 5 cases, 24 patients (14 LyP D, 10 LyP E) were enrolled in the study. The median follow-up was 2.5 years (range 1 month to 13 years). LyP D was characterized by multiple recurrent self-regressing small papules that developed central erosion or necrosis, whereas LyP E presented as papulonodular lesions that rapidly evolved into necrotic eschar-like lesions > 10 mm in size. Epidermal changes were more frequent in LyP D, whereas dermal infiltrates were deeper in LyP E. Anaplastic cytology was rare and the DUSP22 rearrangement was never observed. Two patients (8%) had an associated cutaneous lymphoma. CONCLUSION: LyP D and E have distinct clinical findings and may be associated with other cutaneous lymphomas.

Comparative Study of the Clinical Pathology, Immunophenotype, Epstein-Barr Virus Infection Status, and Gene Rearrangements in Adult and Child Patients With Hydroa Vacciniforme-Like Lymphoproliferative Disorder.

BACKGROUND: Hydroa vacciniforme-like lymphoproliferative disorder (HVLPD) is a rare Epstein-Barr virus (EBV)-associated lymphoma that mainly affects children. OBJECTIVES: To examine the similarities and differences in the clinical pathological features, EBV infection status, and gene rearrangements in adults and children patients with HVLPD. METHODS: We compared the clinical manifestations, histopathology, immunophenotypical features, EBV infection status, and T-cell receptor gene rearrangements in the adult and children HVLPD groups. RESULTS: Clinical manifestations differed between children and adults groups. The children were characterized by blisters and severe facial swelling, whereas the adults were characterized by mild facial swelling and papules. Mosquito bite was significantly related to morbidity in the children group. Histologically, the number of mast cells in the adult group was greater than in the children group (P < 0.05). There were no significant differences in EBV infection status or TCR-γ gene rearrangements between 2 groups. CONCLUSIONS: There were differences in clinical pathology and prognosis between the 2 groups. A higher mast cell count and T-cell phenotype might be associated with a poor prognosis.

SET-NUP214 is a recurrent γδ lineage-specific fusion transcript associated with corticosteroid/chemotherapy resistance in adult T-ALL.

The SET-NUP214 (TAF1/CAN) fusion gene is a rare genetic event in T-cell acute lymphoblastic leukemia (T-ALL). Eleven (6%) of 196 T-ALL patients enrolled in the French Group for Research on Adult Acute Lymphoblastic Leukemia (GRAALL) 2003 and 2005 trials harbored a SET-NUP214 transcript. SET-NUP214-positive patients were predominantly (10 [91%] of 11) T-cell receptor (TCR)-negative and strikingly associated with TCRγδ lineage T-ALLs, as defined by expression of TCRγδ, TCRδ and/or TCRγ rearrangements but no complete TCRß variable diversity joining rearrangement in surface CD3/TCR-negative cases. When compared with SET-NUP214-negative patients, SET-NUP214-positive patients showed a significantly higher rate of corticosteroid resistance (91% vs 44%; P = .003) and chemotherapy resistance (100% vs 44%; P = .0001). All SET-NUP214-positive patients but one achieved complete remission, and 9 were allografted. Despite the poor early-treatment sensitivity, the outcome of SET-NUP214-positive patients was similar to that of SET-NUP214-negative patients.

Id3 and Id2 act as a dual safety mechanism in regulating the development and population size of innate-like γδ T cells.

The innate-like T cells expressing Vγ1.1 and Vδ6.3 represent a unique T cell lineage sharing features with both the γδ T and the invariant NKT cells. The population size of Vγ1.1(+)Vδ6.3(+) T cells is tightly controlled and usually contributes to a very small proportion of thymic output, but the underlying mechanism remains enigmatic. Deletion of Id3, an inhibitor of E protein transcription factors, can induce an expansion of the Vγ1.1(+)Vδ6.3(+) T cell population. This phenotype is much stronger on the C57BL/6 background than on the 129/sv background. Using quantitative trait linkage analysis, we identified Id2, a homolog of Id3, to be the major modifier of Id3 in limiting Vγ1.1(+)Vδ6.3(+) T cell expansion. The Vγ1.1(+)Vδ6.3(+) phenotype is attributed to an intrinsic weakness of Id2 transcription from Id2 C57BL/6 allele, leading to an overall reduced dosage of Id proteins. However, complete removal of both Id2 and Id3 genes in developing T cells suppressed the expansion of Vγ1.1(+)Vδ6.3(+) T cells because of decreased proliferation and increased cell death. We showed that conditional knockout of Id2 alone is sufficient to promote a moderate expansion of γδ T cells. These regulatory effects of Id2 and Id3 on Vγ1.1(+)Vδ6.3(+) T cells are mediated by titration of E protein activity, because removing one or more copies of E protein genes can restore Vγ1.1(+)Vδ6.3(+) T cell expansion in Id2 and Id3 double conditional knockout mice. Our data indicated that Id2 and Id3 collaboratively control survival and expansion of the γδ lineage through modulating a proper threshold of E proteins.

A novel T cell subset with trans-rearranged Vγ-Cß TCRs shows Vß expression is dispensable for lineage choice and MHC restriction.

αß T cells, which express the α-ß TCR heterodimer, express CD4 or CD8 coreceptors on cells that are MHC class I or MHC class II dependent. In contrast, γδ T cells do not express CD4 or CD8 and develop independently of MHC interaction. The factors that determine αß and γδ lineage choice are not fully understood, and the determinants of MHC restriction of TCR specificity have been controversial. In this study we have identified a naturally occurring population of T cells expressing Vγ-Cß receptor chains on the cell surface, the products of genomic trans-rearrangement between the Vγ2 gene and a variety of Dß or Jß genes, in place of an intact TCRß-chain and in association with TCRα. Identification of this population allowed an analysis of the role of TCR variable regions in determining T cell lineage choice and MHC restriction. We found that Vγ2(+)Cß(+) cells are positive for either CD4 or CD8 and are selected in an MHC class II- or MHC class I-dependent manner, respectively, thus following the differentiation pathway of αß and not γδ cells and demonstrating that Vß V region sequences are not required for selection of an MHC-restricted repertoire.

Indolent T-cell lymphoproliferative disease of the gastrointestinal tract.

Primary gastrointestinal (GI) T-cell lymphoma is an infrequent and aggressive disease. However, rare indolent clonal T-cell proliferations in the GI tract have been described. We report 10 cases of GI involvement by an indolent T-cell lymphoproliferative disease, including 6 men and 4 women with a median age of 48 years (range, 15-77 years). Presenting symptoms included abdominal pain, diarrhea, vomiting, food intolerance, and dyspepsia. The lesions involved oral cavity, esophagus, stomach, small intestine, and colon. The infiltrates were dense, but nondestructive, and composed of small, mature-appearing lymphoid cells. Eight cases were CD4(-)/CD8(+), 1 was CD4(+)/CD8(-), and another was CD4(-)/CD8(-). T-cell receptor-γ chain gene rearrangement identified a clonal population in all 10 cases. There was no evidence of STAT3 SH2 domain mutation or activation. Six patients received chemotherapy because of an initial diagnosis of peripheral T-cell lymphoma, with little or no response, whereas the other 4 were followed without therapy. After a median follow-up of 38 months (range, 9-175 months), 9 patients were alive with persistent disease and 1 was free of disease. We propose the name "indolent T-LPD of the GI tract" for these lesions that can easily be mistaken for intestinal peripheral T-cell lymphoma, and lead to aggressive therapy.

CD3-CD4+ lymphoid variant of hypereosinophilic syndrome: nodal and extranodal histopathological and immunophenotypic features of a peripheral indolent clonal T-cell lymphoproliferative disorder.

The CD3(-)CD4(+) lymphoid variant of hypereosinophilic syndrome is characterized by hypereosinophilia and clonal circulating CD3(-)CD4(+) T cells. Peripheral T-cell lymphoma has been described during this disease course, and we observed in our cohort of 23 patients 2 cases of angio-immunoblastic T-cell lymphoma. We focus here on histopathological (n=12 patients) and immunophenotypic (n=15) characteristics of CD3(-)CD4(+) lymphoid variant of hypereosinophilic syndrome. Atypical CD4(+) T cells lymphoid infiltrates were found in 10 of 12 CD3(-)CD4(+) L-HES patients, in lymph nodes (n=4 of 4 patients), in skin (n=9 of 9) and other extra-nodal tissues (gut, lacrymal gland, synovium). Lymph nodes displayed infiltrates limited to the interfollicular areas or even an effacement of nodal architecture, associated with proliferation of arborizing high endothelial venules and increased follicular dendritic cell meshwork. Analysis of 2 fresh skin samples confirmed the presence of CD3(-)CD4(+) T cells. Clonal T cells were detected in at least one tissue in 8 patients, including lymph nodes (n=4 of 4): the same clonal T cells were detected in blood and in at least one biopsy, with a maximum delay of 23 years between samples. In the majority of cases, circulating CD3(-)CD4(+) T cells were CD2(hi) (n=9 of 14), CD5(hi) (n=12 of 14), and CD7(-)(n=4 of 14) or CD7(low) (n=10 of 14). Angio-immunoblastic T-cell lymphoma can also present with CD3(-)CD4(+) T cells; despite other common histopathological and immunophenotypic features, CD10 expression and follicular helper T-cell markers were not detected in lymphoid variant of hypereosinophilic syndrome patients, except in both patients who developed angio-immunoblastic T-cell lymphoma, and only at T-cell lymphoma diagnosis. Taken together, persistence of tissular clonal T cells and histopathological features define CD3(-)CD4(+) lymphoid variant of hypereosinophilic syndrome as a peripheral indolent clonal T-cell lymphoproliferative disorder, which should not be confused with angio-immunoblastic T-cell lymphoma.

Critical role of TCR specificity in the development of Vγ1Vδ6.3+ innate NKTγδ cells.

A large fraction of innate NKTγδ T cells uses TCRs composed of a semi-invariant Vδ6.3/6.4-Dδ2-Jδ1 chain together with more diverse Vγ1-Jγ4 chains. To address the role of γδTCR specificity in their generation, we analyzed their development in mice transgenic (Tg) for a Vγ1-Jγ4 chain frequently expressed by NKTγδ cells (Tg-γ) and in mice Tg for the same Vγ1-Jγ4 chain together with a Vδ6BDδ2Jδ1 chain not usually found among NKTγδ cells (Tg-γδ). Surprisingly, both promyelocytic leukemia zinc finger (PLZF)(+) and NK1.1(+) NKTγδ cells were found in the thymus of Tg-γδ albeit at lower numbers than in Tg-γ mice, and virtually all of them expressed the Tg TCR. However, the PLZF(+) subset, but not the NK1.1(+) subset, also expressed an endogenous Vδ6.3/6.4 chain, and its size was severely reduced in TCRδ(-/-) Tg-γδ mice. These results could suggest that the PLZF(+) and the NK1.1(+) subsets are developmentally unrelated. However, PLZF(+) and NK1.1(+) NKTγδ cells express identical Vδ6.3/6.4 chains, and NK1.1(+) cells can be obtained upon intrathymic injection of sorted PLZF(+) cells, thus indicating their developmental relationship. In fact, the NK1.1(+) γδ thymocytes present in Tg-γδ mice correspond to a small subset of NK1.1(+) γδ thymocytes in wild-type animals, which express a more diverse repertoire of TCRs and can be recognized by the expression of the CD62L Ag. Collectively, our data demonstrated that TCR specificity is essential for the development of most NKTγδ T cells and revealed a developmental heterogeneity in γδ T cells expressing the NK1.1 marker.

Establishment and Characterization of a CD20-Positive NK/T-Cell Lymphoma Cell Line.

BACKGROUND: CD20 positive NK/T-cell lymphoma is extremely rare and difficult for clinical treatment. Due to the lack of an established cell model for this disease, less is known about its biological characterization and potential therapeutic options. METHODS: A cell line of NK/T-cell lymphoma, which was enriched by magnetic sorting with proper cell surface markers (CD56) from peripheral blood mononuclear cells (PBMCs) drawn from a 21-year-old male patient with nasal angiocentric NK/T-cell lymphoma, was designated as ZQNK-29. Immunophenotypic analysis of ZQNK-29 was performed by flow cytometric and immunohistochemical analysis. Comparative genomic hybridization (CGH) analysis was used for cytogenetic analysis of ZQNK-29. Potential rearrangements of the immunoglobulin gene and Epstein-Barr virus (EBV) infection were examined by PCR and RT-PCR, respectively. RESULTS: ZQNK-29 cells express the phenotypic T-cell marker (CD3), T cell activation markers (HLA-DR), markers for both NK and cytotoxic T lymphocytes (TIA-1), and B-lineage marker CD20; however, expression of CD56 was not detected in expanded ZQNK-29 cells although this NK cell surface marker was used as one of selective cell surface markers for the initial isolation of NK/T cells. RT-PCR analysis showed that the pattern of gene expressions for infected EBV was latency type III, with the expressions of LMP1, EBNA-1, and EBNA-2; no rearrangements were found in the heavy-chain of the immunoglobulin gene or in the y chain of the T cell receptors (TCRs) gene. CGH analysis demonstrated that ZQNK-29 possessed an abnormal karyotype, 46XY, 1p (dist)+, 4p (dist)+, 4q (mid)-, 5q (mid)-, 9q (dist)+, 16p (dist)+, 16q (dist)+, 17p+, 17q (dist)+, 19q (dist)+, 20p+, 20q+, 21q+, and 22q+. Of these, 1p (dist)+, which has been confirmed to be mitochondrial DNA amplification, is believed to be mainly caused by EBV infection. CONCLUSIONS: ZQNK-29 is a well characterized premature human NK/T-cell lymphoma cell line with expression of the B-cell marker CD20 and will provide a useful pre-clinic model for characterization and potential therapeutic studies of the aggressive NK/T-cell lymphoma.

[Investigate the clonal origin of different phenotypic tumor-like cells in the epidermis and dermis of skin lesions in lymphomatoid papulosis].

OBJECTIVE: To explore the correlation of the clone sources of MF-like cells in the epidermis and RS-like cells in the dermis of lymphomatoid papulosis (LyP), a compartive study of this two type cells in 8 LyP cases was carried out. METHODS: 8 cases of LyP (4 type A cases and 4 type C cases) were detected the immunophenotype first, and then comparative study between the MF-like cells and RS-like cells was conducted on T-cell receptor (TCR) gamma-chain gene rearrangement by combinating laser capture microdissectinon (LCM) and PCR. PCR products of one patient which had positive bands were selected randomly for sequencing and sequence alignment analysis. RESULTS: Monoclonal TCRgamma gene rearrangement was detected in 6 cases (75%) of the 8 cases. Detection rates of LyP type A and type C were 50% (2/4) and 100% (4/4), respectively. The rates of MF-like cells and RS-like cells were 75% (6/8) and 75% (6/8), respectively. Homology of the products with positive stripes in both MF-like cells and RS-like cells in one randomly selected case was compared and analyzed, and the results showed the homology of them was 106/108 (98%). CONCLUSION: The MF-like cells in the epidermis and the RS-like cells in the dermis of LyP may be from the same clone.

Optimal strategies to identify aberrant intra-epithelial lymphocytes in refractory coeliac disease.

INTRODUCTION: Different strategies have been developed to identify those refractory celiac disease (RCD) patients who are at risk to develop an enteropathy associated T-cell lymphoma (EATL). Flow cytometric analysis of intra-epithelial lymphocytes (IEL) with an aberrant phenotype is considered the golden standard but is not widely available. Immunohistochemistry (IHC) and T-cell receptor (TCR) rearrangement studies are commonly available but may lack sensitivity and specificity. Here, we compared the three different methods in the workup of patients suspected for RCD. METHODS: Duodenal biopsies from control patient (n = 5), RCD patients with moderately increased aberrant IEL populations (20-50 %: n = 14), and RCD patients with high numbers of aberrant IEL (>50 %: n = 5) as determined by flow cytometry were analysed by IHC and TCR-γ chain rearrangement analysis. Three pathologists scored the slides independently. RESULTS: Sensitivity of IHC and TCR-γ rearrangement analysis in RCD patients with high numbers of aberrant IELs was 100 and 71 %, respectively. RCD patients with aberrant cells between 25 and 50 % however, were missed by IHC and TCR in 50 and 57 % of cases, respectively. In addition, inter-rater reliability analysis of the IHC scoring revealed coder-pair Kappa coefficients between 0.28 and 0.85. CONCLUSION: Immunohistochemistry and to a lesser extent TCR-γ clonality analysis are sensitive in identifying patients with high numbers of aberrant IEL populations, yet miss half of RCD patients with moderately increased numbers. In addition, IHC has a high inter-observer variability. Therefore, patients suspected for RCD should undergo flow cytometric analysis of the duodenum.

A unique case of an indolent myometrial T-cell lymphoproliferative disorder with phenotypic features resembling uterine CD8+ resident memory T cells.

OBJECTIVE: Indolent extranodal T-cell lymphoproliferative disorders have recently been described as new entities in the gastrointestinal tract and acral sites displaying clonal T-cell receptor (TCR) rearrangement and nonactivated cytotoxic CD8+ T-cell phenotypes. METHODS/RESULTS: We report a unique case of an atypical myometrial T-cell lymphoproliferation in a 39-year-old multiparous woman, which shares many of the features mentioned above: CD8+/TIA1+/granzyme B- phenotype, clonal TCR rearrangement and indolent course. CONCLUSION(S): We hypothesize that it might derive from a subset of uterine nonrecirculating CD8+ resident memory T cells expanded after repeated exposure to allo-extravillous trophoblastic antigen.

Multiple distinct T-cell clones in folliculotropic mycosis fungoides.

Multiple distinct T-cell clones have been demonstrated in a subset of mycosis fungoides (MF), but have so far not been documented in folliculotropic MF, a clinical and histological variant of MF. We analyzed T-cell receptor (TCR) gene rearrangements in 8 patients with folliculotropic MF with multiple biopsies (range, 2-5) taken during the course of disease. Two patients had disease stage IA-IIA, 5 stage IIB-IVA, whereas data were not available for 1 patient. TCR ß and γ gene rearrangements were analyzed according to the BIOMED-2 PCR protocol. Multiple clonal TCR gene rearrangements indicating more than 1 T-cell clone were found in 5 patients. Although the number of patients is small, the finding of multiple distinct T-cell clones in 5 out of 8 patients suggests that chronic T-cell stimulation contributes to the development of folliculotropic MF.

Lymphomatoid papulosis with associated cerebellar lesion of similar histology and T-cell clonality.

A 9-year old boy presented with a 4-month history of a truncal monomorphic eruption with self-healing papulonecrotic lesions. A skin biopsy revealed a dermal infiltrate of CD4, CD8 and CD30-positive T-cells, consistent with lymphomatoid papulosis. He responded to 4 months of treatment with narrowband UVB phototherapy (311 nm) which stabilised his disease. Five years later he presented with an acute onset of nausea and vomiting, dizziness, headache and ataxia. Magnetic resonance imaging of the brain revealed a lesion in the cerebellum and stereotactic resection was undertaken. Histology showed CD4, CD8 and CD30-positive T-cells similar to his skin lesions, with a monoclonal T-cell receptor (TCR) gamma gene rearrangement. Subsequent analysis of the skin detected a monoclonal band of the same size as the cerebellar lesion. Treatment was initiated for a primary central nervous system (CNS) lymphoma but ceased after one course of high-dose methotrexate. Opinion on the pathology was divided as to whether the cerebellar lesion represented an atypical reactive T-cell lymphoproliferative response or a T-cell lymphoma. On follow-up 2 years later, the patient remains clinically and radiologically clear, making CNS lymphoma unlikely.

T-cell receptor gamma gene rearrangement analysis of classic Hodgkin lymphoma using a BIOMED-2 assay: a paraffin-embedded tissue analysis of one hundred cases.

In the new WHO classifications of haematolymphoid tumours (WHO-HAEM5), classic Hodgkin lymphoma (cHL) is categorized into B-cell lymphoid proliferations and lymphomas. Although the majority of Hodgkin Reed-Sternberg (HRS) cells are of germinal center B-cell origin with some defects of B-cell transcription factors, they rarely express T-cell antigens or cytotoxic molecules. Clonality analyses on cHL samples using BIOMED-2 have been reported by several groups; however, those studies were only focused on Ig regions, including IgH, Ig-kappa, and Ig-lambda, and TCR-γ clonality analysis of cHL has not yet been explored. Here, we investigated TCR-γ gene rearrangement for one hundred cases using a PCR-based method. Four of one hundred (4%) cases showed TCR-γ clonal peaks. Of these, three were at an advanced stage and one patient died of the disease. To clarify whether HRS cells showed T-cell clonality or not, we performed PCR analysis using DNAs of microdissected HRS cells. Three samples showed identical clonal peaks with bulk specimens. Our results indicate that cHL is a heterogeneous disease of mainly B-cell and rarely T-cell origin with a special phenotype. Further molecular studies are warranted.

Anti-tumour immunotherapy with Vγ9Vδ2 T lymphocytes: from the bench to the bedside.

Gamma delta (γδ) Τ cells are non-conventional T lymphocyte effectors that can interact with and eradicate tumour cells. Several data demonstrate that these T cells, which are implicated in the first line of defence against pathogens, have anti-tumour activity against many cancers and suggest that γδ Τ cell-mediated immunotherapy is feasible and might induce objective tumour responses. Due to the importance of γδ Τ lymphocytes in the induction and control of immunity, a complete understanding of their biology is crucial for the development of a potent cancer immunotherapy. This review discusses recent advances in γδ Τ basic research and data from clinical trials on the use of γδ Τ cells in the treatment of different cancers. It analyses how this knowledge might be applied to develop new strategies for the clinical manipulation and the potentiation of γδ Τ lymphocyte activity in cancer immunotherapy.

Generation of diversity by somatic mutation in the Camelus dromedarius T-cell receptor gamma variable domains.

In jawed vertebrates the V-(D)-J rearrangement is the main mechanism generating limitless variations of antigen-specific receptors, immunoglobulins (IGs), and T-cell receptors (TCRs) from few genes. Once the initial diversity is established in primary lymphoid organs, further diversification occurs in IGs by somatic hypermutation, a mechanism from which rearranged TCR genes were thought to be excluded. Here, we report the locus organization and expression of the T-cell receptor gamma (TCRG) genes in the Arabian camel (Camelus dromedarius). Expression data provide evidence that dromedary utilizes only two TCRG V-J genomic arrangements and, as expected, CDR3 contributes the major variability in the V domain. The data also suggest that diversity might be generated by mutation in the productively rearranged TCRGV genes. As for IG genes, the mutational target is biased toward G and C bases and (A/G/T)G(C/T)(A/T) motif (or DGYW). The replacement and synonymous substitutions (R/S) ratios in TCRGV regions are higher for CDR than for framework region, thus suggesting selection toward amino acid changes in CDR. Using the counterpart human TCR γδ receptor as a template, structural models computed adopting a comparative procedure show that nonconservative mutations contribute to diversity in CDR2 and at the γδ V domain interface.

Clonal evolution of adult T-cell leukemia/lymphoma takes place in the lymph nodes.

Adult T-cell leukemia/lymphoma (ATLL) is the neoplasm caused by human T-cell leukemia virus type 1 (HTLV-1). We performed oligo-array comparative genomic hybridization (CGH) against paired samples comprising peripheral blood (PB) and lymph node (LN) samples from 13 patients with acute ATLL. We found that the genome profiles of the PB frequently differed from those of the LN samples. The results showed that 9 of 13 cases investigated had a log2 ratio imbalance among chromosomes, and that chromosome imbalances were more frequent in LN samples. Detailed analysis revealed that the imbalances were likely caused by the presence of multiple subclones in the LN samples. Five of 13 cases showed homozygous loss regions in PB samples, which were not found in the LN samples, indicating that tumors in the PB were derived from LN subclones in most cases. Southern blot analysis of TCRγ showed that these multiple subclones originated from a common clone. We concluded that in many ATLL cases, multiple subclones in the LNs originate from a common clone, and that a selected subclone among the LN subclones appears in the PB.