[Durable remission of T-cell prolymphocytic leukemia with CLEC16A::IL2 after allogeneic hematopoietic stem cell transplantation]

A 64-year-old woman presented with fine motor impairment in both hands. MRI revealed a contrast-enhanced lesion in the medulla oblongata. Lymphoid cells with abnormal blebs were observed and a CD4+/CD8+ double positive (DP) T cell population was detected by flow cytometry (FCM) in the bone marrow (BM) and the peripheral blood (PB). CLEC16A::IL2 fusion gene was identified by whole exome sequencing with DNA prepared from DP T cells. Clonal rearrangement of the T-cell receptor gene and expression of TCL1A protein were detected. This led to a diagnosis of T-cell prolymphocytic leukemia (T-PLL) with central nervous system (CNS) infiltration. Abnormal cells in BM and PB became undetectable on microscopy and FCM, and the CNS lesion disappeared on MRI after second-line therapy with alemtuzumab. Meanwhile, the CLEC16A::IL2 fusion mRNA remained detectable in PB. Allogeneic hematopoietic stem-cell transplantation was performed, and the fusion mRNA has now been undetectable for more than 5 years since transplantation. This is the first report of a T-PLL case with a CLEC16A::IL2 fusion gene.

Long-Smoldering T-prolymphocytic Leukemia: A Case Report and a Review of the Literature

T-prolymphocytic leukemia (T-PLL) is a rare malignancy of mature T-cells with distinct clinical, cytomorphological, and molecular genetic features. The disease typically presents at an advanced stage, with marked leukocytosis, B symptoms, hepatosplenomegaly, and bone marrow failure. It usually follows an aggressive course from presentation, and the prognosis is often considered dismal; the median overall survival is less than one year with conventional chemotherapy. This case report describes a patient with T-PLL who, after an unusually protracted inactive phase, ultimately progressed to a highly invasive, organ-involving disease. After initial treatments failed, a novel treatment approach resulted in a significant response.

T-Cell Prolymphocytic Leukemia: Diagnosis, Pathogenesis, and Treatment

T-cell prolymphocytic leukemia (T-PLL) is a rare and aggressive neoplasm of mature T-cells. Most patients with T-PLL present with lymphocytosis, anemia, thrombocytopenia, and hepatosplenomegaly. Correct identification of T-PLL is essential because treatment for this disease is distinct from that of other T-cell neoplasms. In 2019, the T-PLL International Study Group (TPLL-ISG) established criteria for the diagnosis, staging, and assessment of response to treatment of T-PLL with the goal of harmonizing research efforts and supporting clinical decision-making. T-PLL pathogenesis is commonly driven by T-cell leukemia 1 (TCL1) overexpression and ATM loss, genetic alterations that are incorporated into the TPLL-ISG diagnostic criteria. The cooperativity between TCL1 family members and ATM is seemingly unique to T-PLL across the spectrum of T-cell neoplasms. The role of the T-cell receptor, its downstream kinases, and JAK/STAT signaling are also emerging themes in disease pathogenesis and have obvious therapeutic implications. Despite improved understanding of disease pathogenesis, alemtuzumab remains the frontline therapy in the treatment of naïve patients with indications for treatment given its high response rate. Unfortunately, the responses achieved are rarely durable, and the majority of patients are not candidates for consolidation with hematopoietic stem cell transplantation. Improved understanding of T-PLL pathogenesis has unveiled novel therapeutic vulnerabilities that may change the natural history of this lymphoproliferative neoplasm and will be the focus of this concise review.

[Research Advances of Genetics, Diagnosis and Treatment of T-cell Prolymphocytic Leukemia--Review]

T-cell prolymphocytic leukemia (T-PLL) is a rare but highly aggressive and malignant mature T-lymphoid tumor. The diagnosis of T-PLL mainly depend on genetic characteristics, clinical manifestations, cell morphology and immunophenotype. At present, clinical treatment is mainly aimed at improving the response rate and prolonging the remission period. With the development of new molecular biology technologies, researchers have gained a deeper understanding of the pathogenesis and related genetics of T-PLL, targeted drugs, including HDAC inhibitors, JAK/STAT inhibitors, AKT inhibitors and BCL-2 inhibitors, are also under evolution and providing the new opportunities to improve the efficacy of therapy. In this review, the advances in genetics and treatment of T-PLL were summarized briefly.

Noncanonical effector functions of the T-memory-like T-PLL cell are shaped by cooperative TCL1A and TCR signaling

T-cell prolymphocytic leukemia (T-PLL) is a poor-prognostic neoplasm. Differentiation stage and immune-effector functions of the underlying tumor cell are insufficiently characterized. Constitutive activation of the T-cell leukemia 1A (TCL1A) oncogene distinguishes the (pre)leukemic cell from regular postthymic T cells. We assessed activation-response patterns of the T-PLL lymphocyte and interrogated the modulatory impact by TCL1A. Immunophenotypic and gene expression profiles revealed a unique spectrum of memory-type differentiation of T-PLL with predominant central-memory stages and frequent noncanonical patterns. Virtually all T-PLL expressed a T-cell receptor (TCR) and/or CD28-coreceptor without overrepresentation of specific TCR clonotypes. The highly activated leukemic cells also revealed losses of negative-regulatory TCR coreceptors (eg, CTLA4). TCR stimulation of T-PLL cells evoked higher-than-normal cell-cycle transition and profiles of cytokine release that resembled those of normal memory T cells. More activated phenotypes and higher TCL1A correlated with inferior clinical outcomes. TCL1A was linked to the marked resistance of T-PLL to activation- and FAS-induced cell death. Enforced TCL1A enhanced phospho-activation of TCR kinases, second-messenger generation, and JAK/STAT or NFAT transcriptional responses. This reduced the input thresholds for IL-2 secretion in a sensitizer-like fashion. Mice of TCL1A-initiated protracted T-PLL development resembled such features. When equipped with epitope-defined TCRs or chimeric antigen receptors, these Lckpr-hTCL1Atg T cells gained a leukemogenic growth advantage in scenarios of receptor stimulation. Overall, we propose a model of T-PLL pathogenesis in which TCL1A enhances TCR signals and drives the accumulation of death-resistant memory-type cells that use amplified low-level stimulatory input, and whose loss of negative coregulators additionally maintains their activated state. Treatment rationales are provided by combined interception in TCR and survival signaling.

Consensus criteria for diagnosis, staging, and treatment response assessment of T-cell prolymphocytic leukemia

T-cell prolymphocytic leukemia (T-PLL) is a rare, mature T-cell neoplasm with a heterogeneous clinical course. With the advent of novel treatment options that will potentially change the management of patients with T-PLL, it has become necessary to produce consensus guidelines for the design and conduct of clinical trials. The T-PLL International Study group (TPLL-ISG) set out to define standardized criteria for diagnosis, treatment indication, and evaluation of response. These criteria will facilitate comparison of results from clinical trials in T-PLL, and will thus support clinical decision making, as well as the approval of new therapeutics by healthcare authorities.

Prognostic impact of NOTCH1, MYD88, and SF3B1 mutations in Polish patients with chronic lymphocytic leukemia

INTRODUCTION    Currently available prognostic factors determining the course of chronic lymphocytic leukemia (CLL) are not fully efficient, especially for newly diagnosed patients. Investigation of molecular changes may help clarify the reasons for the heterogeneity of the disease. Apart from already confirmed TP53 mutations, the novel candidates: NOTCH1, SF3B1, and MYD88 might represent clinically relevant biomarkers. OBJECTIVES    The aim of this study was to evaluate the mutational status of NOTCH1, MYD88, and SF3B1 and to compare the results with confirmed prognostic factors: ZAP‑70, CD38, and immunoglobulin heavy‑chain variable region (IGHV) mutation in CLL. The study assessed also prognostic significance in terms of the time to first treatment (TTFT) and subset analysis. PATIENTS AND METHODS The study was conducted on samples of 370 newly diagnosed patients with CLL. The analysis was performed using high‑resolution melting, Sanger sequencing, and polymerase chain reaction methods. RESULTS    Patients harboring the NOTCH1 mutation were significantly more often found among patients with an unmutated IGHV gene status and high expression of CD38 and ZAP‑70. The MYD88 mutation was equally distributed in patients with mutated and unmutated IGHV status (5 vs 7 patients). For MYD88 and SF3B1, there were no significant differences in the levels of CD38 and ZAP‑70 expression. The tendency for lower median TTFT was revealed in patients with mutated SF3B1 (P = 0.08). The analysis showed the presence of 14 different types of the subsets of IGHV in 50 of 345 patients (14.5%). The most frequent were subsets #1 and #2. CONCLUSIONS    The NOTCH1 and SF3B1 mutations accompany biological markers of unfavorable prognosis in patients with CLL. The mutations may contribute to the identification of patients with high‑risk CLL.

TCL-1-positive hematogones in a patient with T-cell prolymphocytic leukemia after therapy

T-prolymphocytic leukemia (T-PLL) is a rare mature T-cell neoplasm characterized by proliferation of prolymphocytes. Most cases involve the T-cell leukemia-1 (TCL1) gene at 14q11.2 resulting in overexpression of TCL-1, which is helpful for distinguishing T-PLL from other T-cell neoplasms. We report a patient with T-PLL whose leukemic cells were positive for TCL-1 by immunohistochemistry but with a normal karyotype. The patient had anti-CD52 antibody therapy for 12 weeks. In a follow-up bone marrow biopsy specimen, numerous TCL-1-positive cells were present, which raised the differential diagnosis of residual T-PLL. However, further immunophenotypic studies confirmed that these cells were hematogones. Therefore a diagnosis of recovering bone marrow was established. The patient underwent stem cell transplant and is now in complete remission. This case demonstrates that hematogones can express TCL-1, and this knowledge is very important for the differential diagnosis in the follow-up marrow of T-PLL patients.

[Cerebriform variant type of T cell prolymphocytic leukemia: Report of one case]

T cell Prolymphocytic Leukemia (T-PLL) is a rare and aggressive mature T cell Lymphocyte Leukemia. Twenty five percent of cases present as a small cell variant, and only 5% as a cerebriform variant. We report a 58 year-old man with rapidly progressive severe leukocytosis, skin lesions, lymphadenopathy, hepatosplenomegaly and pleural effusion. The lymphocytes had a cerebriform type. The diagnosis of T-PLL variant was made by morphology and immunophenotype study of peripheral blood. Karyotype was found to be complex. He was refractory to chemotherapy and died two months later.

T-cell prolymphocytic leukemia in a 63-year-old female with a pre-existing T-cell large granular lymphocytic leukemia: metachronous T-cell leukemias with discordant subset restrictions (CD4 versus CD8) and distinct clonal identities

A 55-year-old female with T-cell large granular lymphocytic leukemia (T-LGL) (CD8+) was initially treated with anti-thymocyte globulin and then cyclosporine due to anemia/neutropenia. While the severity of cytopenia varied with the therapy, the T-LGL persisted. Eight years after the initial diagnosis, she developed lymphadenopathy and hepatosplenomegaly. A complete blood cell count revealed leukocytosis, anemia and thrombocytopenia with ∼ 80% lymphocytes. In contrast to the LGL cells, the blood lymphocytes at this time were medium-large in size and had oval/irregular nuclei, condensed chromatin, indistinct nucleoli and a moderate amount of basophilic cytoplasm, many with elongated vacuoles, and some with cytoplasmic projections. The abnormal lymphocytes comprised ∼ 30% of the bone marrow cellularity with interstitial infiltrates/aggregates. Immunophenotypic analyses demonstrated a T-cell neoplasm with features suggestive of T-cell prolymphocytic leukemia (T-PLL) (CD4+). Cytogenetic analysis revealed a novel clone with complex abnormalities. PCR-based TRG gene rearrangement studies detected a clonal amplicon distinct from that of the preexisting T-LGL. Because of the chronological sequence of the two T-cell neoplasms, this case was initially considered an aggressive transformation of T-LGL. However, this was ultimately excluded by a discordant CD4-subset restriction and the presence of a distinct clonal identity. While these two T-cell neoplasms may have intrinsic connections, the underlying pathogenesis remains to be investigated.

[Splenic rupture associated with aggressive conversion of indolent T-cell prolymphocytic leukemia]

A 65-year-old man was diagnosed with leukocytosis in a routine medical examination. Further laboratory examinations showed increased LDH and sIL-2R levels in the serum. There was no evidence of infiltrative lesions or organomegaly. Bone marrow aspiration revealed many atypical small-sized lymphocytes without apparent nucleoli. Flow cytometric analysis of atypical lymphocytes was positive for T-cell markers, and chromosome analysis showed a normal karyotype. He was diagnosed with the small cell variant of T-PLL. Approximately 34 months later, having received no treatment, his cervical lymph nodes increased in size and number, and his white blood cell count, LDH and sIL-2R levels also rapidly increased. He was then admitted to our hospital. Bone marrow aspiration and cervical lymph node biopsy revealed complex chromosome abnormalities including inv(14)(q11;q32). Computed tomography showed swollen lymph nodes all over his body and hepatosplenomegaly. On the fourth hospital day, spontaneous splenic rupture occurred. Transcatheter arterial embolization was unsuccessful and the patient died. We report this case with rare autopsy findings.

Short telomeres and high telomerase activity in T-cell prolymphocytic leukemia

To test the role of telomere biology in T-cell prolymphocytic leukemia (T-PLL), a rare aggressive disease characterized by the expansion of a T-cell clone derived from immuno-competent post-thymic T-lymphocytes, we analyzed telomere length and telomerase activity in subsets of peripheral blood leukocytes from 11 newly diagnosed or relapsed patients with sporadic T-PLL. Telomere length values of the leukemic T cells (mean+/-s.d.: 1.53+/-0.65 kb) were all below the 1st percentile of telomere length values observed in T cells from healthy age-matched controls whereas telomere length of normal T- and B cells fell between the 1st and 99th percentile of the normal distribution. Leukemic T cells exhibited high levels of telomerase and were sensitive to the telomerase inhibitor BIBR1532 at doses that showed no effect on normal, unstimulated T cells. Targeting the short telomeres and telomerase activity in T-PLL seems an attractive strategy for the future treatment of this devastating disease.

T-cell prolymphocytic leukemia: An aggressive T cell malignancy with frequent cutaneous tropism

BACKGROUND

T-cell prolymphocytic leukemia (T-PLL), formerly categorized as T-cell chronic lymphocytic leukemia, is a rare and aggressive hematologic malignancy. Although the skin is characteristically involved, it is not a well-recognized entity in the dermatologic literature.

METHODS

Six cases of cutaneous T-PLL are presented from a clinical, light microscopic, and phenotypic perspective.

RESULTS

The patient population comprised 2 women and 4 men, with a mean age of 69.8 years. The disease was associated in all with skin involvement with facial preference; edema, purpura, and lesional symmetry were characteristic. The skin biopsies demonstrated a largely non-epidermotropic angiocentric lymphocytic infiltrate with accompanying hemorrhage. The cells showed irregular- to reniform-shaped nuclei with small nucleoli and eosinophilic rims of cytoplasm. Phenotypic studies revealed three prevailing profiles: CD4 dominant in 4, CD8 dominant in one, and co-expression of CD4 and CD8 in one. CD3 loss was seen in one case. All expressed T-cell leukemia 1 (TCL-1) and CD7; cutaneous lymphocyte antigen expression was discernible in a dot-like perinuclear array. All cases tested excluding one expressed TCL-1 and CD52. In two cases tested, T-cell receptor beta rearrangements were observed. Cytogenetic studies demonstrated a paracentromeric chromosome 14 inversion. Polysomy 8 and MYC amplification was seen in one case, manifesting an aggressive clinical course. Four patients died from their disease within 18 months of diagnosis.

LIMITATIONS

Cytogenetic MYC amplification, FISH, and TCR beta studies were conducted on each of 2 cases, respectively, due to limitations of tissue block samples and/or peripheral blood. cMYC translocation studies were conducted on 3 of the 6 cases, again due to limitations imposed by the tissue samples on the cases. The last case was recently diagnosed and, therefore, long-term follow-up is not possible.

CONCLUSION

T-PLL is a distinctive post-thymic T-cell malignancy with frequent cutaneous tropism. A diagnosis is possible in almost all cases based on characteristic clinical, light microscopic, phenotypic, and cytogenetic features. While a chromosome 14 inversion is highly characteristic, additional inherent cytogenetic differences, such as trisomy 8 with CMYC over-amplification, may account for some case to case variation in clinical course.

Involvement of HTLV-I Tax and CREB in aneuploidy: a bioinformatics approach

Background

Adult T-cell leukemia (ATL) is a complex and multifaceted disease associated with human T-cell leukemia virus type 1 (HTLV-I) infection. Tax, the viral oncoprotein, is considered a major contributor to cell cycle deregulation in HTLV-I transformed cells by either directly disrupting cellular factors (protein-protein interactions) or altering their transcription profile. Tax transactivates these cellular promoters by interacting with transcription factors such as CREB/ATF, NF-κB, and SRF. Therefore by examining which factors upregulate a particular set of promoters we may begin to understand how Tax orchestrates leukemia development.

Results

We observed that CTLL cells stably expressing wild-type Tax (CTLL/WT) exhibited aneuploidy as compared to a Tax clone deficient for CREB transactivation (CTLL/703). To better understand the contribution of Tax transactivation through the CREB/ATF pathway to the aneuploid phenotype, we performed microarray analysis comparing CTLL/WT to CTLL/703 cells. Promoter analysis of altered genes revealed that a subset of these genes contain CREB/ATF consensus sequences. While these genes had diverse functions, smaller subsets of genes were found to be involved in G2/M phase regulation, in particular kinetochore assembly. Furthermore, we confirmed the presence of CREB, Tax and RNA Polymerase II at the p97Vcp and Sgt1 promoters in vivo through chromatin immunoprecipitation in CTLL/WT cells.

Conclusion

These results indicate that the development of aneuploidy in Tax-expressing cells may occur in response to an alteration in the transcription profile, in addition to direct protein interactions.

An indolent case of T-prolymphocytic leukemia with t(3;22)(q21;q11.2) and elevated serum beta2-microglobulin

We report a novel case of T-prolymphocytic leukemia, small cell variant, associated with complex cytogenetic findings including t(3;22)(q21;11.2) and elevated serum beta2-microglobulin. The diagnosis is based on morphologic, immunophenotypic, cytogenetic, and molecular analysis of peripheral blood and bone marrow. In contrast to most reported cases of T-prolymphocytic leukemia, this patient did not present with lymphadenopathy or organomegaly. Moreover, only a moderate leukocytosis (25.3 x 10(3)/microL) was evident at presentation. In the absence of any specific treatment, the patient is doing well, with a stable white blood cell count 12 months following presentation. Further investigation may be warranted to determine whether the unusual cytogenetic findings and elevated serum beta2-microglobulin are associated with the indolent clinical course in this patient.

T cell prolymphocytic leukemia with new chromosome rearrangements

A 77-year-old woman presented to the outpatient hematology clinic in August 2001 with leukocytosis, recurrent bacterial infections, sweating and weight loss. Bone marrow biopsy showed 80% infiltration with lymphoid cells having a prolymphocytic morphology. Flow-cytometric immunophenotype analysis showed that over 80% of the cells were positive for CD2, CD3, CD4, CD5 and CD7 antigens and negative for terminal deoxynucleotidyl transferase and CD1a antigens. T cell prolymphocytic leukemia (T-PLL) was diagnosed on the basis of these findings. The diagnosis was later confirmed by cytogenetic analysis and fluorescence in situ hibridization. The patient had the following karyotype: 46,X,der(X)t(X;3) (q28;p25) t(X;16)(p14;q12), der(3) t(X;3)(q28;p25), der(6) t (X;6) (p14;q25), (8) (q10), del(11) (q14q23), der(13) t (5;13) (q34;p11), der(13) t(13;14)(q22;q11), inv(14)(q11q32), der (16) t(X;16)(q28;q12), r(17)(p13q21), der(20) t(17;20) (q21; q13),22p+. The cytogenetic rearrangements der(6)t(X;6) (p14;q25), der(13)t(13;14)(q22;q11),t(5;13)(q34;p11), r(17) (p13q21) and t(17;20)(q21;q13) have not been described previously in the literature in patients with T-PLL.

T-cell large granular lymphocyte leukemia of donor origin after allogeneic bone marrow transplantation

A 39-year-old man with chronic myeloid leukemia in accelerated phase underwent allogeneic bone marrow transplantation (BMT). At 6 months after BMT, lymphocytosis (WBC count, 23,100/microL [23.1 x 10(9)/L]; 80% (0.80) large granular lymphocytes [LGLs]) occurred. The LGLs were CD3+CD4-CD8+, with clonally rearranged T-cell receptor gamma gene, and of donor origin, as shown by analysis of polymorphic microsatellite markers. Epstein-Barr virus was not present. The diagnosis, therefore, was consistent with T-cell large granular lymphocytic (T-LGL) leukemia. Corticosteroids controlled the LGL count, but progressive pancytopenia led to death 4 months later. Retrospective analysis showed that the T-LGL leukemia apparently had arisen as early as 3 months after BMT. The distinguishing features of this case included donor origin, neoplastic nature, and the aggressive fatal outcome.

T-cell prolymphocytic leukemia: update and focus on alemtuzumab (Campath-1H)

T-cell prolymphocytic leukemia (T-PLL) is a rare mature T-cell lymphoproliferative disorder. While the etiology of T-PLL is unknown, recent progress in unraveling the molecular basis of leukemogenesis has been substantial and may yield novel therapeutic targets. T-PLL is a distinct disease entity and the diagnosis can be readily made based on characteristic clinical features and laboratory findings. Prior to the appearance of pentostatin and alemtuzumab in clinical protocols, outcome for T-PLL patients was exceedingly poor with median survival measured in months. While the use of alemtuzumab in particular has improved remissions, the disease remains incurable. Future collaborative efforts investigating novel treatment approaches will be crucial to improving survival for patients with this disease.

Unusually indolent T-cell prolymphocytic leukemia associated with a complex karyotype: is this T-cell chronic lymphocytic leukemia?

T-cell prolymphocytic leukemia (T-PLL) is typically associated with an aggressive clinical course, with a median survival of less than 1 year. We report a case of T-PLL that displays multiple cytogenetic abnormalities, with the most complex subclone having the following karyotype: 47, Y, -X, +8, inv (10) (p12q26), del (11) (p13p15) +marker. However, despite this genetic complexity, the leukemia has behaved in a remarkably indolent manner, with the patient remaining asymptomatic, without therapeutic intervention, for more than 7 years. The unusually benign behavior of this disease calls into question the validity of grouping such cases under the umbrella of T-PLL and warrants a reconsideration of T-cell chronic lymphocytic leukemia (no longer recognized as a distinct disease) as a bona fide diagnostic entity.

Phenotypic transformation of CD52(pos) to CD52(neg) leukemic T cells as a mechanism for resistance to CAMPATH-1H

Immunotherapy utilizing CAMPATH-1H for patients with chemotherapy-refractory chronic lymphocytic leukemia has yielded encouraging results with many reports of complete remission. Here we report the outcome of two patients with CD4-positive T cell prolymphocytic leukemia treated with CAMPATH-1H. Both patients responded rapidly to treatment and subsequently developed CD4 lymphopenia. One patient remained in complete remission after 14 weeks of treatment. Serial peripheral blood flow cytometry revealed that the CD52 antigen was present throughout treatment. The other patient who was initially CD52-positive, became CD52-negative after 6 weeks of treatment, and developed progressive symptoms of T cell prolymphocytic leukemia. Immunotherapy was stopped, chemotherapy proved futile, and the patient died. This change in phenotype from CD52-positive to -negative during CAMPATH-1H therapy points out a need to develop strategies for maintaining antigenic expression during monoclonal antibody therapy.

A complex pattern of recurrent chromosomal losses and gains in T-cell prolymphocytic leukemia

T-cell prolymphocytic leukemia (T-PLL) is a rare malignant proliferation of lymphoid cells with a postthymic phenotype. Previous cytogenetic and molecular studies reported complex karyotypes with recurrent chromosomal abnormalities, including translocations involving either TCL1 at 14q32.1 or MTCP1 at Xq28, inactivation of the ATM gene by deletion and/or mutation, and isochromosomes 8. For extensive study of chromosomal imbalances in T-PLL, we analyzed 22 tumoral DNAs using comparative genomic hybridization (CGH). Abnormal CGH profiles were detected in all cases, demonstrating highly recurrent gains and losses and largely extending the abnormalities previously established. Only a few nonrecurrent abnormalities were observed, in contrast to the genetic instability anticipated from ATM inactivation. Nine recurrent regions of loss were identified at 8p (frequency 86%), 11q (68%), 22q11 (45%), 13q (41%), 6q (36%), 9p (27%), 12p (23%), 11p11-p14 (23%), and 17p (23%), as well as four regions of gain at 8q (82%), 14q32 (50%), 22q21-qter (41%), and 6p (23%). Several recurrent chromosomal abnormalities were simultaneously present in each case (mean, 5.7; up to 10), none being mutually exclusive of another. Fluorescence in situ hybridization analysis confirmed and extended 22q11 and 13q losses, giving final frequencies of 55% and 45%, respectively. Analysis of one case over a 7-year period confirmed the overall genetic stability of T-PLL and showed that tumor progression was associated with the onset of a few chromosomal abnormalities. This study establishes a complex pattern of highly recurrent chromosomal abnormalities in T-PLL, including some, such as chromosome 13 deletion, commonly found in other lymphoid malignancies.

Identification of genes associated with the progression of adult T cell leukemia (ATL)

Patients with adult T-cell leukemia/lymphoma (ATL) exhibit a variety of clinical features, and this disease is therefore clinically subclassified into acute, lymphomatous, chronic, and smoldering types. Acute ATL is a typical leukemic form of ATL with rapid progression, and chronic ATL is a less aggressive clinical form allowing long-term survival even without chemotherapy. In the present study, we used fresh peripheral blood mononuclear cells (PBMC) from both types of ATL patients to identify molecules that may contribute to the difference between acute and chronic ATL. Isolated mRNAs expressed differentially between the two types of ATL include a T-cell differentiation antigen (MAL), a lymphoid-specific member of the G-protein-coupled receptor family (EBI-1 / CCR7), a novel human homologue to a subunit (MNLL) of the bovine ubiquinone oxidoreductase complex, and a human fibrinogen-like protein (hpT49). We found that the former three are upregulated in acute ATL and the last is down-regulated in both chronic and acute ATL. We speculate that dysregulation of the genes may account for the malignant features of ATL cells, in terms of growth, energy metabolism, and motility.

Fluorescent BAT-25 and BAT-26 analysis of T cell prolymphocytic leukaemia

T cell prolymphocytic leukaemia (T-PLL) is a chronic mature T cell malignancy with many random cytogenetic abnormalities. These imply that maintenance of genomic integrity is impaired. This is supported by the recent finding that the ataxia telangiectasia gene, ATM, which contributes to maintaining genomic integrity, is frequently mutated in this disease. To evaluate in T-PLL the role of other genes with comparable function, a fluorescence-based semi-automated assay was developed for BAT-25 and BAT-26. These markers contain sequences that are particularly unstable in cells with DNA mismatch repair defects. Application of the assay to 20 T-PLL cases found no evidence for such defects.

T-cell prolymphocytic leukemia with a novel translocation (6;11)(q21;q23)

T-cell prolymphocytic leukemia (T-PLL) is an uncommon chronic lymphoproliferative disorder characterized by lymphadenopathy, splenomegaly, and lymphocytosis. The leukemic cells have the appearance of prolymphocytes and usually an immunophenotype of T-helper cells (CD3+ CD4+ CD8-). Inv(14q), del(11q), i(8q), and rearranged Xq28 are the commonest nonrandom chromosomal abnormalities in T-PLL. Recently, it has been shown that the ataxia-telangiectasia mutated (ATM) gene located at 11q23 is often deleted in T-PLL, suggesting a tumor suppressor role of the ATM gene on tumorigenesis of T-PLL. We report a case of T-PLL with t(6;11)(q21;q23) as the sole chromosomal abnormality and suggest that the cytogenetically identified translocation also implicates the ATM gene.

Deletions of p15 and/or p16 genes as a poor-prognosis factor in adult T-cell leukemia

PURPOSE

To determine the frequency of the deletions of p15/p16 genes in adult T-cell leukemia (ATL) cells and to evaluate their value in the diagnosis of clinical subtypes of ATL patients and the prediction of their clinical outcome.

MATERIALS AND METHODS

Peripheral-blood samples from 114 patients with ATL were examined by Southern blot analysis. In five chronic-type patients who showed disease progression to acute type, serial samples also were examined.

RESULTS

Among 114 patients, 28 (24.6%) showed the deletions of p15 and/or p16 genes. The results were well correlated with the clinical subtypes. Patients with deleted p15 and/or p16 genes had significantly shorter survival times than the patients in whom both genes were preserved (P < .0001). A similar decline in survival time was observed in the analyses within the same subtypes. In multivariate analysis using the Cox proportional hazard model, the deletions of p15 and/or p16 genes emerged as an independent prognostic indicator. Moreover, three of the five chronic-type patients who progressed to acute type lost the p16 gene alone or both the p15 and p16 genes at their exacerbation phase.

CONCLUSION

The results suggest the following: (1) that the deletions of p15 and/or p16 genes play a key role in the progression of ATL; and (2) that these deletions are reliable prognostic factors that predict shortened survival times.

Chronic lymphatic leukemias of T and NK cell type

T cell chronic lymphocytic/prolymphocytic leukemia (T-CLL/T-PLL) and large granular lymphocyte leukemia of T or NK cell type (T-LGL or NK-LGL leukemia) are chronic lymphoproliferative diseases derived from post-thymic immunocompetent lymphoid cells. T-PLL is morphologically characterized by a prominent central nucleolus in a medium-sized cell expressing a mature T cell immunophenotype. Clonal genetic changes involving chromosome 14 and T cell receptor gene rearrangements are characteristics of these diseases. They are usually progressive and there is no efficient treatment available. The classification of some cases presenting with a morphological picture similar to B-CLL, but with immunophenotypic and clinical features resembling T-PLL, as T-CLL is still controversial. The phenotypic profiles and the establishment of clonality are the hallmarks of defining T-LGL leukemia and NK-LGL leukemia. The CD3+/CD57+/CD56- immunophenotype and the clonal rearrangement of the T cell receptor genes characterize T-LGL leukemia, which presents clinically with a rather indolent course of disease, complicated by frequent infections secondary to neutropenia. NK-LGL leukemia cells express CD3-/CD56+/CD57-, but in most cases clonality cannot easily be established. Clinically the patient may either present with constitutional symptoms and suffer a short and aggressive course of disease or may have a more chronic disease similar to T-LGL leukemia. Therefore, it may be reasonable to subdivide NK-LGL proliferation into the more aggressive 'NK-LGL leukemia/lymphoma' and 'chronic NK cell lymphocytosis'.

The CDKN2 gene alterations in various types of adult T-cell leukaemia

The CDKN2 gene, encoding the cyclin-dependent kinase-4 inhibitor p16, is a putative tumour-suppressor gene because it is frequently altered in many malignant tumours. We analysed the CDKN2 gene in 44 cases of adult T-cell leukaemia (ATL) by Southern blot analysis, polymerase chain reaction-mediated single-strand conformation polymorphism (PCR-SSCP) analysis, and direct sequencing. Southern blot analysis detected a homozygous deletion of the CDKN2 gene in 5/44 patients (11.4%). Mutational analysis by the PCR-SSCP method and direct sequencing showed one nonsense mutation at codon 72 (nucleotide 232), and two missense mutations at codon 43 (nucleotide 146) and codon 97 (nucleotide 309, 3/44, 6.8%). Therefore we found changes in the CDKN2 gene, including point mutations, in 18.2% of the patients with ATL. Interestingly, most of these patients had acute type ATL. Our results suggest that the CDKN2 gene is inactivated not only by homozygous deletion but also by point mutation, and these alterations contribute to the aggressiveness of ATL.

Lack of the expression of EBNA-2 and LMP-1 in T-cell neoplasms possessing Epstein-Barr virus

We investigated 34 cases of T-cell neoplasm [15 cases of T-cell granular lymphocytic leukemia (T-GLL), 10 cases of T-cell non-Hodgkin's lymphoma (T-NHL), six cases of T-cell chronic lymphocytic leukemia (T-CLL), and three cases of cutaneous T-cell lymphoma] to study their association with Epstein-Barr virus (EBV). In 4 (three T-NHL and one T-GLL) of 34 cases, EBV genome was detected in a single episomal form, while polyclonal EBV-DNA was detected in one (T-NHL) of the remaining cases. All three cases of T-NHL having monoclonal EBV episome showed histologically diffuse large-cell lymphoma and developed leukemic conversion. Phenotypic analysis showed that two of these four cases were CD4+, CD8-, and the remaining two cases were CD4-, CD8+. The cells from all four cases were confirmed to be in T-cell lineage by detecting the rearrangement of T-cell receptor (TCR) beta or gamma chain gene. By reverse transcription-polymerase chain reaction (RT-PCR), EBNA-1 was detected at low levels, and neither EBNA-2 nor LMP-1 were found in any of the three cases examined. Lack of the expression of EBNA-2 and LMP-1 was also confirmed by immunocytochemical staining. The cells of these four cases did not show rearrangement or overexpression of c-myc and bcl-2 genes by Southern and Northern blots, and the mutation of p53 gene was detected in only one patient. These results suggest that other latent gene products of EBV or other cellular oncogenes are involved in the development of Japanese T-cell neoplasm after EBV infection.

Multiple karyotypic abnormalities in three cases of small cell variant of T-cell prolymphocytic leukemia

Cytogenetic, clinical, and laboratory findings of three patients with a small cell variant of T-cell prolymphocytic leukemia (T-PLL) are presented. Immunophenotypic studies of the morphologically typical small cell variant prolymphocytes showed a mature helper T-cell phenotype (CD4+CD8-) in one patient and a common thymocyte phenotype (CD4+ CD8+) in two other patients. The cytogenetic analysis revealed complex karyotypes with several structural aberrations in the peripheral blood lymphocytes of all three patients. In all cases chromosome 14 was affected with the breakpoint at 14q11. Inversion (14) and isochromosome 8q, often reported as an additional aberration in T-PLL, were detected in two of the patients. In two patients a translocation of the short arm of chromosome 12 was also seen. The T-cell receptor beta-chain gene showed a clonal rearrangement in all three patients, whereas no rearrangements were detected in the immunoglobulin genes. The survival of the patients ranged from 10 weeks to 48 months. The association between cytogenetic, clinical, and laboratory data is discussed.

Combined immunophenotyping and karyotyping in peripheral T cell lymphomas demonstrating different clonal and nonclonal chromosome aberrations in T helper cells

Combined immunophenotyping and karyotyping was performed in seven cases of peripheral T cell lymphoma with complex aberrant clones. Various lymphocytic cell populations entered mitosis, whereas all aberrant cells belonged to the T helper/inducer cell population. Lymphomas with the same recurrent chromosome aberrations, i.e. inversion inv(14)(q11q32.1) and isochromosome i(8)(q10), had a very similar immunophenotype. The aberrant cells in these cases expressed CD3+, CD4+, CD7+, CD45RO+. The immunophenotypic similarity is underlined in one case of T prolymphocytic leukemia, in whom the aberrant cells lost the CD8 antigen originally present, during cultivation with PHA. In one case of Sézary's syndrome, two or possibly even three different clones as well as nonclonal aberrations were identified within the T (helper/inducer) cell population, providing further evidence that chromosomal instability is a characteristic feature of cutaneous T cell lymphoma.

HLA class I self peptides isolated from a T-cell leukemia reveal the allele-specific motif of HLA-B38

Naturally-processed self peptides bound to HLA class I molecules of a T-cell leukemia (HLA-A1, A31, B38, B58) were isolated for sequence analysis. Acid-eluted peptides were subjected to reversed-phase HPLC separation and single-fraction sequencing was performed by Edman degradation. The peptides were found to be mostly nonamers and could be grouped into three distinct structural motifs. One of the peptide groups consistently displayed histidine at position 2 and a bulky hydrophobic residue at the C-terminus (XHXPXXXXY/F). The only HLA class I structure expressed by this T-cell leukemia which is consistent with the binding of peptides carrying this sequence motif is HLA-B38. A peptide binding assay confirmed this assignment. HLA-B38 is present in 10-12% of the Jewish population and is associated with several autoimmune disorders. The HLA-B38 motif may be an important tool for identifying potential T-cell epitopes involved in these diseases and for designing peptide vaccines.

Vacuolated glycogen-laden leukemic cells in a case of crisis type chronic adult T-cell leukemia

We present a unique case of crisis type chronic adult T-cell leukemia (ATL), in which the majority of leukemic cells had abundant periodic acid-Schiff (PAS)-positive cytoplasmic inclusions. These inclusions were found to be composed of glycogen because the PAS-positivity completely disappeared after digestion with amylase or human saliva. Electron microscopy also revealed that the inclusions consisted of aggregated beta particles of glycogen. The mechanism of glycogen accumulation in leukemic cells remains unknown; however, the presence of such inclusions in leukemic cells may be helpful diagnostically in T-lymphocyte malignancies.

Molecular analysis of T-cell receptor V beta chains of human T-cell chronic lymphocytic leukemia does not show intraclonal variability: implications for immunotherapy

Human T-cell chronic lymphocytic leukemia (T-cell CLL) is a heterogeneous disease characterized by a monoclonal malignant proliferation of T cells in which the T-cell receptors (TCRs) can be, when expressed, considered to be membrane tumor-specific antigens. Owing to the increasing number of available monoclonal antihuman TCR reagents, it could be of interest to evaluate the feasibility of anti-TCR treatment during T-cell CLL. To test the therapeutic potentiality of anti-TCR monoclonal antibodies, we first analyzed the intraclonal variability in two terminally ill patients suffering from TCR alpha beta-positive cell CLL bearing different immunophenotypes. The cDNA corresponding to the variable regions of the TCR beta chains originating from the malignant T cells were amplified, cloned into M13 phages, and sequenced. The sequence analysis of multiple independent clones showed no intraclonal variability, with no evidence for ongoing hypermutation in the V beta region genes. The relevance of these findings with regard to an anti-V beta therapy and the comparison with similar analysis during B-cell monoclonal lymphoproliferations are discussed.

An HTLV-I carrier who developed CD4+ T-CLL expressed the IL-2 receptor beta chain alone without expressing the alpha chain

We describe a case of T-chronic lymphocytic leukaemia (T-CLL) with monoclonal proliferation of CD3+4+8- T cell expressing the interleukin 2 receptor (IL-2R) beta chain without expressing the alpha chain. Southern blot analysis of T-cell receptor beta chain gene revealed rearranged bands. The serum antibody was positive against human T-cell lymphotropic virus type I (HTLV-1)-associated antigens, but monoclonal integration of proviral DNA was not detected in the leukaemic cells. In accordance with the expression of IL-2R beta chain, the leukaemic cells proliferated in response to exogenous IL-2 without prior stimulation. However, culture supernatants of these cells did not show IL-2 activity. Since the role of the IL-2R beta chain in freshly isolated cells from T-CLL patients is not well understood, detailed analysis of this case would give us valuable information on the role of IL-2/IL-2R system in the proliferation of the leukaemic T cells.

Lineage promiscuity in leukemia studies of T-cell receptor and immunoglobulin genes

Using appropriate DNA probes, the configurations of the T-cell receptor beta-chain genes and immunoglobulin heavy-chain genes were studied in patients diagnosed as having the following malignancies: 7 chronic myeloid leukemia, 13 acute myeloblastic leukemia, 9 acute lymphocytic leukemia and 20 chronic lymphocytic leukemia. Rearrangements not corresponding to the immunotype were unexpectedly found in lineage neoplasias.

Human T cell leukaemia virus type 1 p21X mRNA: constitutive expression in peripheral blood mononuclear cells of patients with adult T cell leukaemia

Although the p21X protein of human T cell leukaemia virus type 1 (HTLV-1) is generally thought to be expressed from a doubly spliced mRNA transcript (tax/rex mRNA) that encodes the p40tax, p27rex and p21X proteins, we have shown previously that a novel, alternatively spliced mRNA transcript (p21X mRNA) is responsible for p21X production in HTLV-1-infected cell lines. In the present study, we analysed expression of p21X mRNA and tax/rex mRNA in uncultured and cultured peripheral blood mononuclear cells (PBMCs) from eight patients with adult T cell leukaemia by using a quantitative polymerase chain reaction coupled to reverse transcription. The results demonstrated that the expression of p21X mRNA occurs constitutively in all uncultured and cultured PBMCs, whereas the expression of tax/rex mRNA is inducible in the cultured PBMCs, as described previously. In uncultured and cultured PBMCs from the one specimen in which p21X mRNA was highly expressed, the p21X protein was detectable by Western blotting. On the other hand, p27rex protein was detectable only after cultivation. These findings indicate that p21X mRNA is constitutively expressed in vivo and is responsible for production of p21X protein.

T-cell chronic lymphocytic leukemia. Unusual morphologic, phenotypic, and karyotypic features in association with light chain amyloidosis

BACKGROUND

Lymphocytes that display a phenotype of mature B-cells, T-cells, natural killer (NK) cells, or a combination of T-cells and NK cells can be found in patients with lymphoproliferations that manifest as expansions of peripheral blood lymphocytes (PBL). If these PBL expansions exhibit clonality, they can be classified as chronic lymphocytic leukemia (CLL).

METHODS/RESULTS

A patient who had two simultaneous, clonal lymphoproliferative disorders manifested as an unusual T-cell CLL in conjunction with systemic light chain amyloidosis is described. Gene rearrangement studies of the PBL of the patient showed clonal rearrangements of both the T-cell receptor beta (T beta) chain and the immunoglobulin genes. Additional immunologic and microscopic studies of the T-cells of the patient showed that they were large, agranular, CD4+ T-cells that also expressed the NK cell marker CD57. Cytogenetics disclosed an unusual karyotype in the PBL.

CONCLUSIONS

The pathogenesis of this T-cell CLL and whether it truly represents a malignant disorder, as well as its relation to amyloidosis, is discussed.