Chronic Adult T-cell Leukemia Research Articles

Enlarged, multifocal upper limb neuropathy with HTLV-I associated myelopathy in a patient with chronic adult T-cell leukemia

The authors herein describe a case of multifocal peripheral neuropathy with HTLV-I-associated myelopathy (HAM) in a patient with chronic adult T-cell leukemia (ATL). The clinical features included subacute progressive sensory-motor neuropathy in the bilateral upper limbs, and bilateral pyramidal tract involvement with bladder dysfunction. An MRI with 67gadolinium enhancement revealed enlargement of the affected peripheral nerves. 8FDG positron emission tomography (PET) disclosed increased uptake in the affected nerves, suggesting neurolymphomatosis or inflammation. Anti-HTLV-I antibody was positive in both the serum and CSF. The HTLV-I proviral load in the peripheral blood mononuclear cells was high. Chemotherapy for ATL resulted in marked improvement of motor functions in the upper limbs. This is the first case of multifocal upper limb neuropathy with HAM in a patient with chronic ATL.

Serological identification of adult T‐cell leukaemia‐associated antigens

Adult T-cell leukaemia (ATL) is a peripheral T-cell neoplasm caused by human T-cell leukaemia virus type I (HTLV-I). Several clinical observations suggest that some tumour-associated antigens in ATL may be recognised by the immune system. In this study, we performed the serological screening of an expression library to identify ATL-associated antigens by using materials from a unique ATL patient with long-term stable disease. Among five distinct genes isolated, serine/arginine protein kinase 1 (SRPK1), which has been reported to have a restricted normal tissue distribution, was found to be overexpressed in most acute type ATL samples, but not in chronic type ATL or in normal peripheral blood mononuclear cells by real-time reverse transcription polymerase chain reaction. Interestingly, the overexpression of SRPK1 in aggressive types of ATL was more exclusively observed at the protein level than at the mRNA level. Autologous antibody to SRPK1 was confirmed in the ATL patient using Western blot analysis with plasma, but not detected in asymptomatic HTLV-I carriers or in healthy volunteers. These results indicate that SRPK1 may be useful for the development of therapeutic and diagnostic methods for patients with ATL.

Matrix metalloproteinase-9 and vascular endothelial growth factor: a possible link in adult T-cell leukaemia cell invasion.

Plasma from a total of 57 patients with adult T-cell leukaemia (ATL) (acute ATL, 39 patients; lymphoma ATL, one patient; chronic ATL, 15 patients; smouldering ATL, two patients) and 20 healthy controls was analysed for the presence of type IV gelatinase activity with clinical features. A significant elevation of plasma matrix metalloproteinase-9 (MMP-9) was observed in some ATL patients, particularly in the patients with malignant cell infiltration. MMP-9 was found to be secreted into the conditioned medium from all ATL cell lines examined. Moreover, the corresponding mRNA was detectable both in all ATL cell lines examined and in the majority of primary acute ATL cells, indicating that ATL cells are capable of synthesizing and secreting MMP-9. We previously demonstrated that a high incidence of ATL cell infiltration was closely related to a high plasma level of vascular endothelial growth factor (VEGF) produced by ATL cells themselves. This present study showed that the presence of increased plasma MMP-9 was closely associated with elevated plasma VEGF in ATL patients. Furthermore, we showed that both increased plasma MMP-9 and VEGF were significantly related to high ATL cell infiltration. All these findings strongly suggest that MMP-9 and VEGF act co-operatively in the process of ATL cell invasion.

Arsenic Trioxide Induces Apoptosis in HTLV-I Infected T-cell Lines and Fresh Adult T-cell Leukemia Cells Through CD95 or Tumor Necrosis Factor α Receptor Independent Caspase Activation

Arsenic trioxide (As2O3) has been reported to induce apoptosis in human T-cell leukemia virus type-I (HTLV-I) infected T-cell lines and fresh adult T-cell leukemia (ATL) cells and to induce G1 phase accumulation in HTLV-I infected T-cell lines. The present study aimed to clarify the pathway of As2O3-induced apoptosis in HTLV-I infected T-cell lines, MT-1 and MT-2, and fresh ATL cells separated from peripheral blood of patients with acute or chronic type ATL. Cells were treated up to 72 h at clinically tolerable concentrations of As2O3 (1–2 µmol/l) shown to be safe in patients with acute promyelocytic leukemia (APL). Activation of caspases 3, 8, and 9, loss of mitochondrial transmembrane potential and cleavage of poly (adenosine diphosphate-ribose) polymerase (PARP) were observed during As2O3 treatment. Furthermore, prior exposure to a broad-spectrum caspase inhibitor blocked As2O3-induced apoptosis but not G1 phase accumulation. While pre-treatment with a CD95 receptor-blocking antibody (Ab) or a TNF-α neutralizing Ab did not show such inhibitions in these cells. In conclusion, As2O3 induces apoptosis in HTLV-I infected T-cell lines and fresh ATL cells through CD95 or TNF-α receptor independent caspase activation.

Possible involvement of interferon regulatory factor 4 (IRF4) in a clinical subtype of adult T-cell leukemia.

Interferon regulatory factor (IRF) 4 is the lymphoid‐specific transcription factor that is required for the proliferation of mitogen‐activated T cells. IRF4 has been suggested to be involved in tuniorigenesis because the overexpression of IRF4 caused the transformation of Rat‐1 fibroblasts in vitro. Here, we show that IRF4 is constitutively expressed in adult T‐cell leukemia (ATL)‐derived cell lines, which were infected with human T‐cell leukemia virus type‐I, but hardly expressed the trans‐activator protein, Tax. Similarly, constitutive expression of IRF4 was demonstrated in freshly isolated peripheral blood mononuclear cells (PBMC) from patients with either acute or chronic ATL. However, the high‐level expression of IRF4 was specifically associated with acute ATL. With mitogen‐activated PBMC from healthy donors, cell cycle analyses revealed that the induction of IRF4 occurred prior to cell cycle progression and the cells that had entered the cell cycle were predominantly IRF4‐positive cells. In addition, ectopic expression of IRF4 in Rat‐1 fibroblasts increased the S and G2/M phase population significantly. Taken together, our results indicate that IRF4 is involved in the pathogenesis of ATL through its positive effect on the cell cycle, and that IRF4 can be used as a molecular marker of clinical subtype in ATL.

Expression of functional lung resistance–related protein predicts poor outcome in adult T-cell leukemia

Chemotherapy of patients with adult T-cell leukemia (ATL) has been unsuccessful. The poor outcome is thought to be caused mainly by the drug resistance of ATL cells. Lung resistance-related protein (LRP) is a novel protein associated with drug resistance. The expression of LRP messenger RNA (mRNA) was evaluated by slot blot analysis in 55 patients with ATL. Of these patients, 36 had acute, 12 chronic, and 7 lymphoma-type ATL. The expression levels of LRP mRNA were significantly higher in chronic ATL than in lymphoma-type ATL (P =.007). The expression of LRP mRNA was higher in patients with white blood cell counts above 30,000/microL (P =.038) or with abnormal lymphocyte counts above 10,000/microL (P =.007) than in the remaining patients. The enhanced efflux of [(14)C]doxorubicin from nuclei isolated from ATL cells that expressed high levels of LRP was inhibited by a polyclonal antibody against LRP, and the accumulation of doxorubicin in the isolated nuclei was increased by the anti-LRP antibody. In acute and lymphoma-type ATL patients, high expression of LRP mRNA at diagnosis correlated with shorter survival, and a Cox proportional hazards model showed that LRP expression is an independent prognostic factor. These findings suggest that functionally active LRP is expressed in some ATL cells and that it is involved in drug resistance and poor prognosis in ATL. (Blood. 2001;98:1160-1165)

Existence of escape mutant in HTLV-I tax during the development of adult T-cell leukemia

AbstractAlthough Tax protein is the main target of cytotoxic T lymphocyte (CTL) on human T-cell lymphotropic virus type I (HTLV-I)–infected cells, and Tax peptide 11 through 19 binding to HLA-A*02 has been shown to elicit a strong CTL response, there are patients with adult T-cell leukemia (ATL) bearing HLA-A*02. To explore whether there is genetic variation in HTLV-I tax that can escape CTL recognition during the development of ATL, the HTLV-I tax gene was sequenced in 55 patients with ATL, 61 patients with HTLV-I–associated myelopathy/tropical spastic paraparesis (HAM/TSP), and 62 healthy carriers, and it was correlated with the presence of HLA-A*02. First, a premature stop codon in the 5′ half of the tax gene that looses transactivation activity on the viral enhancer was observed in 3 patients with acute and 1 patient with chronic ATL. This stop codon was revealed to emerge after the viral transmission to the patient from sequence analysis in family members with ATL. Second, amino acid change in Tax peptide 11-19 was observed in 3 patients with ATL. CTL assays demonstrated that this altered Tax 11-19 peptide, observed in ATL patients with HLA-A*02, was not recognized by Tax 11-19–specific CTL. Two patients with ATL had large deletions in tax by sequencing, and 5 patients with ATL had deletions in HTLV-I by Southern blotting. These findings suggest that at some stage of ATL development, HTLV-I–infected cells that can escape the host immune system are selected and have a chance to accumulate genetic alterations for further malignant transformation, leading to acute ATL.

HTLV-I Tax Related Dysfunction of Cell Cycle Regulators and Oncogenesis of Adult T Cell Leukemia

HTLV-I is causually related to the oncogenesis of adult T cell leukemia (ATL). However, the precise mechanism of HTLV-I oncogenesis is unclear. HTLV-I Tax protein functions as an activator of various cellular genes, including IL-2, IL-2 receptor-α, and c-fos through the activation of nuclear transfer factors such as NF-kB and SRF, and also potently activates trascription of viral genes through CREB/ATF sites in the viral LTR. However, Tax activation of HTLV-I infected T cells through the above pathways induces polyclonal proliferation of the cells in vitro; Tax however may function only transiently in the immediate post-infection period following infection in vivo. The long latent period of 60 years from infection to onset of disease suggests other mechanisms for ATL oncogenesis. Recent studies suggest that the malignant transformation of ATL is a multi-hit phenomena, suggesting that discrete genetic events are responsible for ATL oncogenesis. These genetic events could be responsible for the different stages of ATL: smoldering, chronic, lymphoma, and acute type. p16 and p53 genes are important negative regulators of the cell cycle and are often found to be mutated in neoplasms. Recent studies including ours demonstrated a high frequency of alteration of these two genes in primary ATL cells. Furthermore, alteration of the two genes is associated with acute but not chronic type ATL. In addition, p16 gene alteration is linked to the growth rate of ATL cells, suggesting that the alteration of these cell cycle regulatory genes may be related to progression from smoldering or chronic to acute or lymphoma type ATL. Tax may be involved in mutagenesis of these genes through suppression of DNA-β polymerase gene expression during the process from latent period to acute/lymphoma type. Once transformation occurs, activation of the pathway between Tax and the three nuclear transfer factors, NF-kB, SRF, and CREB/ATF, contributes to establish the aggressive manifestations of acute/lymphoma type ATL cells.

Case of adult T‐cell leukemia resulting in spontaneous remission and pancytopenia

American Journal of HematologyVolume 65, Issue 4 p. 325-326 Letters and CorrespondenceFree Access Case of adult T-cell leukemia resulting in spontaneous remission and pancytopenia Kazuhiko Muraki, Kazuhiko Muraki Division of Hematology, Department of Medicine, Yamaguchi Prefecture Central Hospital, Hofu, JapanSearch for more papers by this authorKenji Shinohara, Kenji Shinohara Division of Hematology, Department of Medicine, Yamaguchi Prefecture Central Hospital, Hofu, JapanSearch for more papers by this authorToru Takahashi, Toru Takahashi Division of Hematology, Department of Medicine, Yamaguchi Prefecture Central Hospital, Hofu, JapanSearch for more papers by this authorItsuro Ota, Itsuro Ota Division of Hematology, Department of Medicine, Yamaguchi Prefecture Central Hospital, Hofu, JapanSearch for more papers by this authorRyohei Nawata, Ryohei Nawata Division of Hematology, Department of Medicine, Yamaguchi Prefecture Central Hospital, Hofu, JapanSearch for more papers by this author Kazuhiko Muraki, Kazuhiko Muraki Division of Hematology, Department of Medicine, Yamaguchi Prefecture Central Hospital, Hofu, JapanSearch for more papers by this authorKenji Shinohara, Kenji Shinohara Division of Hematology, Department of Medicine, Yamaguchi Prefecture Central Hospital, Hofu, JapanSearch for more papers by this authorToru Takahashi, Toru Takahashi Division of Hematology, Department of Medicine, Yamaguchi Prefecture Central Hospital, Hofu, JapanSearch for more papers by this authorItsuro Ota, Itsuro Ota Division of Hematology, Department of Medicine, Yamaguchi Prefecture Central Hospital, Hofu, JapanSearch for more papers by this authorRyohei Nawata, Ryohei Nawata Division of Hematology, Department of Medicine, Yamaguchi Prefecture Central Hospital, Hofu, JapanSearch for more papers by this author First published: 07 November 2000 https://doi.org/10.1002/1096-8652(200012)65:4<325::AID-AJH16>3.0.CO;2-UCitations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat References 1Murakawa M, Shibuya T, Teshima T, Kudo J, Okamura T, Harada M, Nagafuji S, Niho Y, Mukae T. Spontaneous remission from acute exacerbation of chronic adult T-cell leukemia. Blut 1990; 61: 346– 349. 2Shimamoto Y, Kikuchi M, Funai N, Suga K, Matsuzaki M, Yamaguchi M. Spontaneous regression in adult T-cell leukemia/lymphoma. Cancer 1993; 72: 735– 740. 3Shirono K, Hirai N, Inada T, Tsuda H, Ishihara A, Miyayama H. Adult T-cell leukemia with cytomegalovirus associated hemophagocytic syndrome (abstract in English). Jpn J Clin Hematol 1994; 35: 177– 182. 4Matsushita K, Arima N, Fujiwara H, Hidaka S, Ohtsubo H, Arimura K, Kukita T, Okamura M, Tei S. Spontaneous remission associated with apoptosis in a patient with acute-type adult T-cell leukemia. Am J Hematol 1999; 61: 144– 148. 5Debatin K-M, Goldman CK, Waldmann TA, Krammer PH. Apo-1-induced apoptosis of leukemia cells from patients with adult T-cell leukemia. Blood 1993; 81: 2972– 2977. Citing Literature Volume65, Issue4December 2000Pages 325-326 ReferencesRelatedInformation

Adult T-cell leukemia cells over-express the multidrug-resistance-protein (MRP) and lung-resistance-protein (LRP) genes.

Adult T-cell leukemia (ATL) is a T-cell malignancy caused by human T-cell-leukemia-virus-I (HTLV-I) infection. ATL comprises 4 clinical forms: acute, chronic, smoldering and lymphoma types. ATL is usually resistant to conventional chemotherapy and has a relatively poor prognosis; however, the resistance mechanisms remain undetermined. To explore the multidrug-resistance (MDR) mechanisms of ATL, we examined the expression and functional activity of MDR-related genes in peripheral-blood mononuclear cells (PBMC) from ATL patients by semi-quantitative RT-PCR and FACScan with calcein-AM. PBMC from ATL patients expressed similar or higher levels of MRP, LRP and cMOAT mRNAs, as compared with normal PBMC. In normal controls and ATL patients, MDR1 mRNA expression was undetectable in this study. PBMC from acute and chronic ATL patients expressed significantly higher levels of MRP and LRP mRNA than did normal PBMC (p < 0.01 and p < 0.05 respectively). In chronic ATL, positive correlations were apparent between levels of MRP and LRP mRNA expression (r = 0.759, p = 0.018), and between each mRNA level and the absolute number of abnormal lymphocytes in peripheral blood. Probenecid, an inhibitor of the MRP pump, significantly increased the accumulation of calcein in PBMC from 3 chronic ATL patients. Our findings suggest that the MRP and LRP genes in ATL are often activated by HTLV-I infection and may confer MDR of ATL cells in vivo. Combined chemotherapy with inhibitors of these MDR genes may be promising in the treatment of ATL.

Alteration of p16 (CDKN2) gene is associated with interleukin-2–induced tumor cell growth in adult T-cell leukemia

Because tumorigenesis frequently involves the dysfunction of cell cycle-related proteins, we examined the effect of mutations in CDK inhibitor p16 and its linked genomic loci p15, cl.B, and 1063.7 on the growth of primary adult T-cell leukemia (ATL) cells. Southern blot analysis of primary ATL cells showed a significantly higher incidence of p16 gene alteration in acute ATL than in chronic ATL [67.7% (23/34) vs 26.1% (6/23), respectively; p < 0.003]. Similarly, polymerase chain reaction (PCR) analysis of p16 exon 2 revealed a higher incidence of alteration in acute ATL than in chronic ATL [52.9% (18/34) vs 26.1% (6/23), respectively; p < 0.05]. PCR-single strand conformation polymorphism analysis of exons 1 and 2 of p16 showed no mutations in the patients, with normal pattern by Southern blotting or PCR analysis. Notably five of six chronic ATL patients with abnormal p16 genes progressed to acute crisis within 4 months. PCR analysis of the p16 linked loci 1063.7, p15 exon 2, and cl.B found homozygous deletion in 55.9%, 20.6%, and 2.9% of acute ATL cells and 39.1%, 13.0%, and 0% of chronic ATL cells, respectively, showing no relationship of homozygous deletion in either loci with disease subtypes. In most cases, deletions were seen in multiple genes, including p16. Acute ATL cells had a higher frequency of multigene deletions than chronic ATL cells [44.1% vs 17.4%; p < 0.05]. When leukemic cells were analyzed for interleukin 2 (IL-2) responsive growth, only p16 gene alteration was directly associated with leukemic cell growth activity. Among leukemic cells showing high IL-2 responsiveness, 73.1% (19/26) had p16 gene alteration vs 27.8% (5/18) of leukemic cells that showed low IL-2 responsiveness ( p < 0.005). p16 gene alteration was found in 73.3% (14/19) of leukemic cells showing high autonomous growth rates but in only 40.0% (10/25) of those leukemic cells showing low autonomous growth ( p < 0.03). These results suggest the following: alteration of p16-related genomic regions in ATL is usually a wide rearrangement including the p16 gene; within this region, only p16 gene alteration is associated with disease aggressiveness; and p16 gene deletion may be a proximate event in leukemogenesis.

LEUKEMOGENESIS AND PROGRESSION OF ADULT T-CELL LEUKEMIA

O-15 Following infection with human T-cell leukemia virus type I (HTLV-I), a long latent period is required for the development of frank adult T-cell leukemia (ATL), suggesting that accumulated genetic or epigenetic changes of the host genes are involved in leukemogenesis. In HTLV-I+ carriers, CD4+ memory T-cells increase in accordance with HTLV-I provirus load. In contrast, both CD4+ and CD8+ naive T-cells decrease, which might account for the immunodeficiency associated with HTLV-I infection. Phenotypes of increased CD4 memory T-cells are similar to those of ATL cells, suggesting that HTLV-I viral protein(s), especially Tax, promotes the proliferation of infected cells, leading to the onset of ATL. Cyclin-dependent kinase inhibitor, p16 gene, is one of tumor suppressor genes, whose deletions have been shown to be associated with high-grade malignant ATL. We examined the methylation profile of p16 in various HTLV-I-infected cell populations using methylation-specific PCR (MSPCR) following sodium bisulfite treatment. A high frequency of methylation of p16 gene was identified in ATL samples and HTLV-I-transformed cell lines. Sequencing of p16 revealed that the CpG sites of p16 were more frequently methylated in fresh leukemic cells than detected with MSPCR. Fresh leukemic cells isolated from acute and lymphoma-type ATL cases had more methylated sites than those from chronic or smoldering ATL cases. These data suggest that the CpG sites of p16 are methylated at greater levels as the disease progresses, resulting in the suppression of p16 expression. Although Tax has been shown to functionally inactivate p16, the methylation of p16 also appears to play a critical role in regulating p16 in HTLV-I-associated leukemogenesis.

Correlation of telomerase activity with development and progression of adult T-cell leukemia

Telomerase is an enzyme that adds hexameric TTAGGG nucleotide repeats to the ends of vertebrate chromosomal DNAs (i.e. telomeres) to compensate for losses that occur with each round of DNA replication. Telomerase activity, demonstrable in most human tumors, enables them to maintain telomere stability. Peripheral blood mononuclear cells were sampled from 57 patients seropositive for human T-lymphotropic virus type I (HTLV-I), including 24 asymptomatic viral carriers, ten smoldering type, five chronic type, and 18 acute type adult T-cell leukemia (ATL). Telomerase activity was determined in samples using a modified telomeric repeat amplification protocol. We semiquantitatively determined telomerase activity by serial dilution of each sample. All of 23 samples from acute and chronic type ATL patients were positive, seven of ten (70%) smoldering type patients and seven of 24 (29.2%) asymptomatic viral carriers were positive. Disease progression from asymptomatic viral carrier to acute type correlated with telomerase activity. Two samples from chronic type ATL patients with relatively high telomerase activity progressed to the acute type within 1 month. Serum lactate dehydrogenase level also correlated with telomerase activity. These results indicate that reactivation of telomerase activity is a key event in development and progression of ATL, and telomerase could be a useful marker for predicting the course of disease. Accordingly, ATL could be a good candidate disease for trials of telomerase inhibitors, as novel anticancer drugs.

High Rate of Chromosomal Abnormalities in HTLV-I-Infected T-Cell Colonies Derived from Prodromal Phase of Adult T-Cell Leukemia: A Study of IL-2-Stimulated Colony Formation in Methylcellulose

To detect chromosomal abnormalities in prodromal phase of adult T-cell leukemia (ATL), we established a clonal culture method for human T-lymphotropic virus type I (HTLV-I) infected T-cells in methylcellulose containing recombinant human interleukin 2 (rhIL-2). We tried to analyze chromosomes of 187 colonies (4, 23, 69, 74, and 17, from HTLV-I-uninfected normal T-cells, HTLV-I-Infected normal T-cells, HTLV-I carriers, smoldering ATL, and chronic ATL, respectively), using chromosomal banding methods. In the prodromal group, 53% of colonies (84/160) (36/69, 37/74, 11/17 in HTLV-I carriers, smoldering ATLs, and chronic ATL, respectively) had chromosomal abnormal clones. In HTLV-I carriers, multiple clones with simple chromosomal abnormalities were observed. In more progressed chronic ATL, more complex chromosomal abnormalities were detected, and specific colonies were selected. Thus, colonies in the prodromal phase of ATL are characterized by cytogenetical clonal evolution and clonal changes.

The methylthioadenosine phosphorylase gene is frequently co-deleted with the p16INK4a gene in acute type adult T-cell leukemia.

Adult T-cell leukemia (ATL) is a retrovirus-associated leukemia with poor prognosis and often has deletions of the p16INK4a and p15INK4b genes on chromosome 9p21. The gene for methylthioadenosine phosphorylase (MTAP), a purine and methionine metabolic enzyme, resides approximately 100 Kb telomeric to the p16INK4a gene and is frequently co-deleted with the tumor suppressor gene in a variety of cancers. This enzyme deficiency can be exploited for selective chemotherapy with de novo purine synthesis inhibitors and/or methionine depletion. To determine whether ATL can be a candidate for selective chemotherapy based on genetic alterations on chromosome 9p21, we analyzed the MTAP gene in 41 samples from ATL patients (27 acute type and 14 chronic type ATL) and 3 cell lines established from ATL patients. Five samples from the acute type had deletions of the MTAP gene (4 total deletions and 1 partial deletion of exons 6-8). The MTAP gene was always co-deleted with p16INK4a. No deletion of the MTAP gene was detected in samples from the chronic type. Of 3 cell lines, 2 showed partial deletions of exons 5-8 of the MTAP gene, and 1 lost all exons. The p16INK4a gene was deleted in all cell lines. In conclusion, deletions of the MTAP gene were found in 5 of 27 acute type ATL samples. Acute type ATL with MTAP deficiency can be a good candidate for selective chemotherapy by depleting purines and/or methionine.

Quantitative characterization and potential function of membrane Fas/APO-1 (CD95) receptors on leukaemic cells from chronic B and T lymphoid leukaemias.

The expression and function of the Fas-receptor (Fas-R) were examined in chronic lymphocytic leukaemia (CLL), hairy cell leukaemia-variant (HCL-v) and adult T-cell leukaemia (ATL). The expression of Fas-R in freshly isolated leukaemic cells was qualitatively and quantitatively different between each disease; faint in B-CLL, moderate in HCL-v and strong in ATL. Both full-length and alternatively spliced truncated forms of Fas mRNA were detected even in CLL B cells with faint to negative Fas-R, and Fas mRNA was also shown to be capable of increasing in vitro expression, i.e. the message was functional. In contrast, Fas-R expression on ATL cells was heterogenous and usually intense with a mean density approximately 3-fold higher than that of normal T cells. Fas-R was confirmed to have the potential function for anti-Fas monoclonal antibody-mediated cell death in vitro in Fas-R+ ATL cells. The expression level of Fas-R on the cells was higher in chronic than acute ATL (10,360 v 6260 antibody-binding capacity per cell, mFasABC; P<0.05) and was inversely correlated with serum LDH activity, suggesting that the strong Fas-R accounts for the slow progression of chronic ATL and the negative Fas-R protects from Fas-mediated cell death. These results show that Fas-R expression on leukaemic cells is valuable in their characterization and perhaps their function, and may contribute to the progression and immune evasion of malignant clones.

Serum dehydroepiandrosterone and DHEA-sulfate in patients with adult T-cell leukemia and human T-lymphotropic virus type I carriers

The serum levels of dehydroepiandrosterone (DHEA) and DHEA-sulfate (DHEA-S) were determined by radioimmunoassay in 38 patients with adult T-cell leukemia (ATL). Levels of serum DHEA and DHEA-S were also measured in 60 human T-lymphotropic virus type I (HTLV-I) carriers, and did not differ from those in 60 healthy control subjects. Serum levels in patients with ATL were lower than those in the age- and sex-matched healthy controls and in HTLV-I carriers with statistical significance. Serum DHEA and DHEA-S in male patients with acute and lymphoma-type ATL were 1.06 +/- 0.77 ng/ml and 245.8 +/- 192.9 ng/ml, respectively. Levels in male patients with chronic and smoldering-type ATL were 1.69 +/- 0.68 ng/ml and 477.6 +/- 251.5 ng/ml, respectively. Serum levels of DHEA and DHEA-S in patients with acute and lymphoma-type ATL were significantly lower than those in patients with chronic and smoldering-type ATL (P < 0.05). These data suggest that a decrease in serum levels of DHEA and DHEA-S may be associated with patients who have some clinical subtypes of ATL. Moreover, androgens may have a therapeutic role in patients with ATL, as administered in patients with hairy-cell leukemia. Because there is at present no curative chemotherapy for ATL, a trial combination of androgens and standard chemotherapy may be a reasonable therapeutic option in such patients.

Characterization and regulation of interleukin‐4 receptor in adult T‐cell leukemia cells

We studied the expression of the receptor of interleukin (IL-4), one of the T cell growth factors, on fresh peripheral blood leukemic cells from adult T-cell leukemia (ATL) patients. Flow cytofluorometric analysis with a monoclonal antibody to the IL-4 receptor (IL-4R) were used to investigate whether expression of IL-4R on ATL cells is different from that on normal lymphocytes and other types of leukemic cells. Leukemic cells from acute type ATL patients synthesize IL-4R without stimulation, at levels much higher than normal resting lymphocytes and other types of leukemic cells. Furthermore, leukemic cells from acute type ATL showed higher IL-4R expression than that of chronic type ATL or human T-cell leukemia virus type I carriers. In addition, there was correlation between expression of IL-4R on the cell surface and the proliferative response to IL-4. Both IL-4 and IL-2 induced upregulation of IL-4R on activated normal T cells but not on ATL cells. These results suggest that abnormal expression of IL-4R may display different biological activities in ATL compared with other types of leukemia. Furthermore, the high expression of IL-4R in ATL may be involved in the proliferation of leukemic cells and the leukemogenesis in this disease.

Homozygous Deletions of the p15 (MTS2) and p16 (CDKN2/MTS1) Genes in Adult T-Cell Leukemia

Adult T-cell leukemia (ATL) is associated with prior infection with human T-cell leukemia virus type I (HTLV-I). Twenty to 40 years often elapse from viral infection to overt ATL, suggesting that other genetic events must occur to produce frank leukemia. The p15 (MTS2) and p16 (CDKN2/MTS1) genes located on chromosome 9p have been implicated as candidate tumor-suppressor genes in several types of tumors. We examined for alterations of these genes in ATL using Southern blot and polymerase chain reaction-single-strand conformation polymorphism analyses. Both p15 and p16 genes were homozygously deleted in 4 of 23 acute/lymphomatous ATL (17%). An additional 3 (13%) and 4 (17%) acute/lymphomatous samples had hemizygous deletions in at least one exon of p15 and p16, respectively. One of 14 chronic ATL samples had a homozygously deleted p16 gene and another had a hemizygous deletion of p16. Neither homozygous nor hemizygous deletions of the p15 gene were found in chronic ATL. In total, 10 of 37 (27%) ATL samples had loss of the p15 and/or p16 genes. No point mutations of the p15 and p16 genes were found. The ATL patient with a homozygously deleted p16 in the chronic phase rapidly progressed to acute ATL and died within 6 months of the initial diagnosis. One instructive patient had no detectable deletion of the p15 and p16 genes during the chronic phase of ATL but had a homozygous deletions of both genes when she progressed to acute ATL. Our results suggest an association of p15/p16 deletions with development of acute ATL.

Clinical significance of serum thymidine kinase in adult T-cell leukaemia and acute myeloid leukaemia.

To clarify the clinical and biological significance of serum thymidine kinase (TK) in adult T-cell leukaemia (ATL) associated with human lymphotropic virus type-I (HTLV-I) and in acute myeloid leukaemia (AML), TK was measured in 52 patients with ATL (acute ATL, 35 patients; lymphoma ATL, two patients; chronic ATL, 12 patients; smouldering ATL, three patients), and in 27 patients with AML (one FAB MO, one M1, 10 M2, seven M3, five M4, one M5, one M6, one MU). In ATL patients, statistical analysis disclosed a close correlation between TK level and the leucocyte count (P < 0.01), and absolute number of abnormal lymphocytes (P < 0.01). However, no correlation was observed between serum lactic dehydrogenase (LDH) level and these items. Concerning the therapeutic response, a statistical difference was present in TK between complete remission and no response (P < 0.05), but not in LDH. We also investigated a significant inverse correlation between TK level as well as LDH level and the length of survival after the initial diagnosis (P < 0.01). In AML patients a close correlation of TK level with the count of leucocytes (P < 0.01), percentage of blasts in the blood (P < 0.05), therapeutic response (P < 0.01) and the length of survival after the initial diagnosis (P < 0.05) was present. Therefore the TK level may indicate the aggressiveness of leukaemic cells and predict the response to the chemotherapy and the length of survival in ATL and AML.