Human T-cell Leukemia Virus I Research Articles

A-109 A novel multi-cytokine inhibitory strategy in treating HTLV-1 diseases

Human T-cell leukemia virus-I (HTLV-1) is the most oncogenic human virus and arguably the most carcinogenic agent to humans (Gallo, Willems and Tagaya, 2017, Martin et al, 2018). Nevertheless, HTLV-1 is not receiving the deserving attention. We have been advocating for HTLV-1 to enhance the visibility of its research and to make the public aware of its biological and social importance for the past few years as a part of HTLV-1 task force of Global Virus Network (GVN), and we believe we are seeing some promising changes. Despite nearly 40 years of extensive research on the mechanisms by which HTLV-1 causes multiple human diseases including adult T-cell leukemia (ATL), HAM/TSP (HTLV-1 associate myelopathy/Tropical Spastic Paraparesis), and immunosuppressive condition leading to bacterial infections, no reliable cures are available for these diseases. HTLV-1 infection to CD4 T-cells enhances the production of multiple cytokines by CD4 T-cells through the transactivating nature of virus genes such as Tax. This causes a by-stander activation of CD8 T-cells and turn them into inflammatory cells, which contributes to worsening the disease burden in HTLV-1 diseases. For example, the damages to spinal cord cells in HAM/TSP is caused by the inflammatory CD8 T-cells. We have shown that such activation of CD8 T-cells is mainly caused by the cooperation of IL-2 and IL-15, 2 sibling cytokines belonging to the common gamma (γc)-family (Nata et al 2015, Massoud et al 2015) and that only the co-inhibition of these 2 cytokines, but not the inhibition of either of them, effectively suppresses the activation of CD8 T-cells isolated from HAM/TSP patients in an ex vivo assay system. The co-inhibition of 2 cytokines is a clinical challenge because currently available modalities do not allow to accomplish the goal without adverse effects. For example, monoclonal antibodies need to be combined, but is infeasible in the clinic from the viewpoint of cost. Bispecific antibodies do not exist to co-inhibit these 2 cytokines. Signal inhibitors such as Jak kinase inhibitors will have profound side effects by broadly blocking non-γc cytokines such as Erythropoietin and Thrombopoietin and causing severe anemia and bleeding tendency. Even specific JAk3 inhibitors, if available, will cause immunodeficiency by blocking IL-7 and significantly reducing the number of T-cells when used chronically. We thus developed a novel technology to develop inhibitors which block only desired members of the γc-family cytokines. We noted that all γc-tyokines (eg, IL-2, -4, -7, -9-, 15, and −21) use their D-helices to interact with the shared γc-receptor subunit. Accordingly, we found that the D-helices from 6 γc-cytokine show modest conservation in their primary structure. We postulated that a short peptide mimicking these D-helices might inhibit multiple γc-cytokines by competing with them in the binding to the γc, and that leveraging the conserved and non-conserved positions in this region across all γc-cytokines might allow us to synthesize a specific inhibitor to a given choice of γc-cytokines. We in fact successfully synthesized several peptides showing inhibition to only selected γc-cytokines, but not all γc-cytokines with different target spectrums. Among them is the BNZ-1 peptide which blocks IL-2, IL-15 and IL-9. In an ex vivo assay using T-cells derived from HAM/TSP patients, BNZ-1 effectively blocked the proliferation and activation of HAM/TSP T-cells whereas mAb for IL-2 or IL-15 only showed marginal inhibition, suggesting that this compound represents a novel therapeutic candidate for HAM/TSP. It is likely that BNZ-1 could treat chronic ATL as well since chronic ATL has been shown to pathogenically involve IL-2 and IL-15 produced by HTLV-1 infected CD4 T-cells. We have tested the safety, pharmacokinetics and pharmacodynamics of the PEGylated form of the BNZ-1 peptide (BNZ-1/PEG) in animal models (mouse and non-human primate) and in healthy human volunteers (Phase I study) and observed that it blocks IL-2 and IL-15 activity effectively in humans, and that a weekly or biweekly administration maintains the drug level above the minimum effective dose. BNZ-1/PEG has been approved as an IND for treating HAM/TSP and T-cell malignancies (CD8 type LGL-leuekmia/cutaneous T-cell Lymphoma (CTCL)). Currently we are conducting a phase II clinical trial involving LGL-leukemia/CTCL (see a poster presented by J Geh et al) and are aiming at starting a trial involving HAM/TSP in the near future.

Suppression of Human T-cell Leukemia Virus I Gene Expression by Pokeweed Antiviral Protein

Human T-cell leukemia virus I (HTLV-I) is a deltaretrovirus that is the causative agent of adult T-cell leukemia and the neurological disorder HTLV-I-associated myelopathy/tropical spastic paraparesis. Currently, no effective antiretroviral treatment options are available to restrict the development of diseases associated with the virus. In this work, we investigated the activity of pokeweed antiviral protein (PAP) on HTLV-I, when expressed from a proviral clone in 293T cells or in an HTLV-I immortalized cell line. PAP is a plant-derived N-glycosidase that exhibits antiviral activity against a number of viruses; however, its mode of action has not been clearly defined. Here, we describe the mechanism by which PAP inhibited production of HTLV-I. We show that PAP depurinated nucleotides within the gag open reading frame and suppressed the synthesis of viral proteins in part by decreasing the translational efficiency of HTLV-I gag/pol mRNA. Observed reduction in levels of viral mRNAs were not due to enhanced degradation; rather, decreased amounts of viral transactivator protein, Tax, led to feed-back inhibition of transcription from the viral promoter. Therefore, PAP efficiently suppressed HTLV-I gene expression at both translational and transcriptional levels, resulting in substantially diminished virus production. Significantly, no changes in viability or rates of cellular transcription or translation were observed in cells expressing PAP, indicating that this protein was not toxic. Antiviral activity, together with the absence of cytotoxicity, supports further investigation of this enzyme as a novel therapeutic agent against the progression of HTLV-I infection.

Identification of a functional serum response element in the HTLV-I LTR

In response to various mitogenic signals, serum response factor (SRF) activates cellular gene expression after binding to its cognate target sequence (CArG box) located within a serum response element (SRE). SRF is particularly important in T cell activation, and we now report that SRF activates basal transcription from the human T-cell leukemia virus-I (HTLV-I) long terminal repeat (LTR). A DNA element, with similarity to the consensus cellular CArG box found in the c- fos promoter centered approximately 120 base pairs upstream from the viral transcription start site, has been identified and named the vCArG box. SRF activation of gene expression from the LTR was localized to the vCArG box, and mutation of this site abolished SRF responsiveness. An oligonucleotide probe containing the vCArG box bound purified SRF, and a complex formed on this probe with nuclear extract was supershifted by anti-SRF antibody. Moreover, a biotinylated probe containing the vCArG box bound SRF in avidin–biotin pull-down assays. Quantitative binding analysis yielded nanomolar affinities for both the viral and cellular CArG boxes. Chromatin immunoprecipitation experiments demonstrated that SRF is resident on the HTLV-I LTR in vivo. These data identify a functional serum response element in the HTLV-I LTR and suggest that SRF may play an important role in regulating basal HTLV-I gene expression in early infection and reactivation from latency.

Identification of a functional serum response element in the HTLV-I LTR

In response to various mitogenic signals, serum response factor (SRF) activates cellular gene expression after binding to its cognate target sequence (CArG box) located within a serum response element (SRE). SRF is particularly important in T cell activation, and we now report that SRF activates basal transcription from the human T-cell leukemia virus-I (HTLV-I) long terminal repeat (LTR). A DNA element, with similarity to the consensus cellular CArG box found in the c- fos promoter centered approximately 120 base pairs upstream from the viral transcription start site, has been identified and named the vCArG box. SRF activation of gene expression from the LTR was localized to the vCArG box, and mutation of this site abolished SRF responsiveness. An oligonucleotide probe containing the vCArG box bound purified SRF, and a complex formed on this probe with nuclear extract was supershifted by anti-SRF antibody. Moreover, a biotinylated probe containing the vCArG box bound SRF in avidin–biotin pull-down assays. Quantitative binding analysis yielded nanomolar affinities for both the viral and cellular CArG boxes. Chromatin immunoprecipitation experiments demonstrated that SRF is resident on the HTLV-I LTR in vivo. These data identify a functional serum response element in the HTLV-I LTR and suggest that SRF may play an important role in regulating basal HTLV-I gene expression in early infection and reactivation from latency.

Human T-cell Leukemia Virus-I Tax Oncoprotein Functionally Targets a Subnuclear Complex Involved in Cellular DNA Damage-Response

The virally encoded oncoprotein Tax has been implicated in HTLV-1-mediated cellular transformation. The exact mechanism by which this protein contributes to the oncogenic process is not known. However, it has been hypothesized that Tax induces genomic instability via repression of cellular DNA repair. We examined the effect of de novo Tax expression upon the cell cycle, because appropriate activation of cell cycle checkpoints is essential to a robust damage-repair response. Upon induction of tax expression, Jurkat T-cells displayed a pronounced accumulation in G2/M that was reversible by caffeine. We examined the G2-specific checkpoint signaling response in these cells and found activation of the ATM/chk2-mediated pathway, whereas the ATR/chk1-mediated response was unaffected. Immunoprecipitation with anti-chk2 antibody results in co-precipitation of Tax demonstrating a direct interaction of Tax with a chk2-containing complex. We also show that Tax targets a discrete nuclear site and co-localizes with chk2 and not chk1. This nuclear site, previously identified as Tax Speckled Structures (TSS), also contains the early damage response factor 53BP1. The recruitment of 53BP1 to TSS is dependent upon ATM signaling and requires expression of Tax. Specifically, Tax expression induces redistribution of diffuse nuclear 53BP1 to the TSS foci. Taken together these data suggest that the TSS describe a unique nuclear site involved in DNA damage recognition, repair response, and cell cycle checkpoint activation. We suggest that association of Tax with this multifunctional subnuclear site results in disruption of a subset of the site-specific activities and contributes to cellular genomic instability.

NF-kappaB signaling pathway governs TRAIL gene expression and human T-cell leukemia virus-I Tax-induced T-cell death.

The Tax oncoprotein encoded by human T-cell leukemia virus induces both T-cell activation and apoptosis. The mechanism by which Tax induces apoptosis has remained unclear. Using genetically manipulated T-cell lines, we demonstrate that Tax-induced T-cell death is dependent on NF-kappaB signaling. Tax fails to induce apoptosis in T cells lacking IkappaB kinase gamma (IKKgamma), an essential component of the NF-kappaB signaling pathway. This defect was rescued when the mutant cells were reconstituted with exogenous IKKgamma. We further demonstrate that the Tax-induced T-cell death is mediated by TNF (tumor necrosis factor)-related apoptosis-inducing ligand (TRAIL), because this event can be effectively inhibited by a TRAIL-blocking antibody. Consistent with this functional aspect, Tax stimulates the expression of TRAIL mRNA. Finally, we provide genetic evidence demonstrating that the NF-kappaB signaling pathway is essential for TRAIL gene induction by both Tax and T-cell activation signals. These studies reveal a novel function of the NF-kappaB signaling pathway and suggest a key mechanism by which Tax induces T-cell death.

Induction of Tax i expression in MT-4 cells by 5-azacytidine leads to protein binding in the HTLV-1 LTR in vivo.

The Tax I trans-activator protein of the human T-cell leukemia virus I (HTLV-I) enhances viral gene expression through enhancer sequences in the viral LTR. These sequences consist of three imperfect 21-bp repeats (TRE-1) and a region between the promoter central and promoter proximal TRE-1 (known as TRE-2). We have previously described the in vivo footprint of the HTLV-I TRE-1s and TRE-2 in two HTLV-I-infected cell lines, MT-2 and MT-4. MT-2 is a high-level producer of virus and shows significant DNA-protein interactions within the TRE-1s and TRE-2. In contrast, the proviral DNA in MT-4 cells is heavily methylated and produces no detectable virus. In this report, we describe the footprints of the TRE-1s and TRE-2 in MT-4 cells that were induced to express high levels of viral proteins by treatment with 5-azacytidine, a potent inhibitor of methylation. The footprints of the TRE-1s in 5-azacytidine-treated MT-4 cells were virtually identical to those observed in MT-2 cells. In contrast, the footprints within the TRE-2 region of 5-azacytidine-treated MT-4 cells did not resemble those in either MT-2 or MT-4 cells.

Inhibition of NF-κB induces apoptosis of KSHV-infected primary effusion lymphoma cells

AbstractKaposi sarcoma–associated herpesvirus (KSHV), or human herpervirus 8 (HHV-8), is a γ-herpesvirus that infects human lymphocytes and is associated with primary effusion lymphoma (PEL). Currently, the role of viral infection in the transformation of PEL cells is unknown. One possibility is that KSHV, like the lymphotropic viruses Epstein-Barr virus (EBV) and human T-cell leukemia virus I (HTLV-I), activates the transcription factor NF-κB to promote survival and proliferation of infected lymphocytes. To examine this possibility, we assessed NF-κB activity in KSHV-infected PEL cell lines and primary tumor specimens by electrophoretic mobility shift assay (EMSA). We observed that NF-κB is constitutively activated in all KSHV-infected lymphomas, and consists of 2 predominant complexes, p65/p50 heterodimers and p50/p50 homodimers. Inhibition experiments demonstrated that Bay 11-7082, an irreversible inhibitor of IκBα phosphorylation, completely and specifically abrogated the NF-κB/DNA binding in PEL cells. PEL cells treated with Bay 11 demonstrated down-regulation of the NF-κB inducible cytokine interleukin 6 (IL-6), and apoptosis. These results suggest that NF-κB activity is necessary for survival of KSHV-infected lymphoma cells, and that pharmacologic inhibition of NF-κB may be an effective treatment for PEL.

Inhibition of NF-κB induces apoptosis of KSHV-infected primary effusion lymphoma cells

Kaposi sarcoma–associated herpesvirus (KSHV), or human herpervirus 8 (HHV-8), is a γ-herpesvirus that infects human lymphocytes and is associated with primary effusion lymphoma (PEL). Currently, the role of viral infection in the transformation of PEL cells is unknown. One possibility is that KSHV, like the lymphotropic viruses Epstein-Barr virus (EBV) and human T-cell leukemia virus I (HTLV-I), activates the transcription factor NF-κB to promote survival and proliferation of infected lymphocytes. To examine this possibility, we assessed NF-κB activity in KSHV-infected PEL cell lines and primary tumor specimens by electrophoretic mobility shift assay (EMSA). We observed that NF-κB is constitutively activated in all KSHV-infected lymphomas, and consists of 2 predominant complexes, p65/p50 heterodimers and p50/p50 homodimers. Inhibition experiments demonstrated that Bay 11-7082, an irreversible inhibitor of IκBα phosphorylation, completely and specifically abrogated the NF-κB/DNA binding in PEL cells. PEL cells treated with Bay 11 demonstrated down-regulation of the NF-κB inducible cytokine interleukin 6 (IL-6), and apoptosis. These results suggest that NF-κB activity is necessary for survival of KSHV-infected lymphoma cells, and that pharmacologic inhibition of NF-κB may be an effective treatment for PEL.

Inhibition of Caspase Cascade by HTLV-I Tax Through Induction of NF-κB Nuclear Translocation

AbstractNF-κB is required for prevention of apoptosis. We examined the importance of human T-cell leukemia virus–I (HTLV-I) Tax protein to stimulate NF-κB nuclear translocation, thus preventing apoptosis. Jurkat cells and JPX-9 cells in which the inducible Tax expression plasmid vector was stably transfected were used in the present study. Both Jurkat and Tax− JPX-9 cells had small amounts of basal nuclear NF-κB activity. The addition of NF-κB inhibitors suppressed NF-κB nuclear translocation of the cells, thus inducing apoptosis. Sequential activation of caspases from caspase-8 to caspase-3 was shown during this process. NF-κB nuclear translocation in JPX-9 cells was stimulated through Tax expression, and both the activation of caspases and apoptosis induced by NF-κB inhibitors were significantly suppressed in the Tax+ JPX-9 cells. The expression of Bcl-2, Bax, and Bcl-x was not changed among Jurkat, Tax− JPX-9, and Tax+ JPX-9 cells in the presence or absence of NF-κB inhibitors. X-chromosome–linked inhibitor of apoptosis (XIAP) protein expression in Tax−JPX-9 cells was significantly suppressed by NF-κB inhibitors, however, its expression in Tax+ JPX-9 cells was maintained even by the addition of NF-κB inhibitors. Our results suggest that the activation of NF-κB via Tax protein in HTLV-I infected cells renders the cells resistant to apoptosis. The expression of anti-apoptotic gene products such as XIAP to suppress caspase cascade, results in an increase of cytokine production and cell proliferation; one of the proposed mechanisms that promotes autoimmune disorders such as Sjögren's syndrome and rheumatoid arthritis found in HTLV-I seropositive subjects.

Inhibition of Caspase Cascade by HTLV-I Tax Through Induction of NF-κB Nuclear Translocation

NF-κB is required for prevention of apoptosis. We examined the importance of human T-cell leukemia virus–I (HTLV-I) Tax protein to stimulate NF-κB nuclear translocation, thus preventing apoptosis. Jurkat cells and JPX-9 cells in which the inducible Tax expression plasmid vector was stably transfected were used in the present study. Both Jurkat and Tax− JPX-9 cells had small amounts of basal nuclear NF-κB activity. The addition of NF-κB inhibitors suppressed NF-κB nuclear translocation of the cells, thus inducing apoptosis. Sequential activation of caspases from caspase-8 to caspase-3 was shown during this process. NF-κB nuclear translocation in JPX-9 cells was stimulated through Tax expression, and both the activation of caspases and apoptosis induced by NF-κB inhibitors were significantly suppressed in the Tax+ JPX-9 cells. The expression of Bcl-2, Bax, and Bcl-x was not changed among Jurkat, Tax− JPX-9, and Tax+ JPX-9 cells in the presence or absence of NF-κB inhibitors. X-chromosome–linked inhibitor of apoptosis (XIAP) protein expression in Tax−JPX-9 cells was significantly suppressed by NF-κB inhibitors, however, its expression in Tax+ JPX-9 cells was maintained even by the addition of NF-κB inhibitors. Our results suggest that the activation of NF-κB via Tax protein in HTLV-I infected cells renders the cells resistant to apoptosis. The expression of anti-apoptotic gene products such as XIAP to suppress caspase cascade, results in an increase of cytokine production and cell proliferation; one of the proposed mechanisms that promotes autoimmune disorders such as Sjögren’s syndrome and rheumatoid arthritis found in HTLV-I seropositive subjects.

Sensorimotor polyneuropathy associated with chronic lymphocytic leukemia, IgM antigangliosides antibody and human T‐cell leukemia virus I infection

A 65-year-old man presented with a sensorimotor polyneuropathy associated with B-cell chronic lymphocytic leukemia (CLL) and immunoglobulin M (IgM) antibody to various gangliosides. Electrophysiological studies denoted significant abnormalities of motor and sensory nerve conduction. Although the pathology of sural nerve biopsy looked minimally affected, immunohistochemical studies showed specific binding of IgM to the human peripheral nerve. Our patient also had high titer of antibody to human T-cell leukemia virus I (HTLV-I) in both serum and cerebrospinal fluid (CSF), which might activate B-cell–mediated immunity and facilitate the production of IgM antibody. The other unique feature is the reactivity of antibody to gangliosides. The patient had IgM antibody reactivities to gangliosides with disialosyl residue such as GT1b, GQ1b and GD3, but not to GD1b. IgM antibody to gangliosides with disialosyl residue has been reported in ataxic symptoms, but our patient failed to demonstrate ataxia. Without reactivity to GD1b, sensory ataxic neuropathy might not develop even in the presence of antibody reactive to other gangliosides with disialosyl residue. © 1999 John Wiley & Sons, Inc. Muscle Nerve 22: 1461–1465, 1999

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.

Human T Cell Leukemia Virus-I (HTLV-I) Tax-Mediated Apoptosis in Activated T Cells Requires an Enhanced Intracellular Prooxidant State

We have shown that an estradiol-dependent activation of human T cell leukemia virus-I Tax leads to the inhibition of cell proliferation and to the induction of apoptosis. The present study demonstrates that a hormone-dependent activation of Tax promotes an enhanced prooxidant state in stably transfected Jurkat cells as measured by changes in the intracellular levels of glutathione and H2O2; these changes are followed by apoptotic cell death. Additional stimulation of the CD3/TCR pathway enhances the oxidative and apoptotic effects. Both Tax-mediated apoptosis and oxidative stress can be potently suppressed by antioxidants, as is seen with the administration of recombinant thioredoxin (adult T cell leukemia-derived factor) or pyrrolidine dithiocarbamate. Hormone-induced Tax activation induces a long-lasting activation of NF-kappaB, which is a major target of reactive oxygen intermediates. The long-term exposure of Jurkat cells to hormone eventually results in a selection of cell clones that have lost Tax activity. A subsequent transfection of these apparently "nonresponsive" clones allows the recovery of Tax responses in these cells. Our observations indicate that changes in the intracellular redox status may be a determining factor in Tax-mediated DNA damage, apoptosis, and selection against the long-term expression of Tax function.

Genes in the pX region of human T cell leukemia virus I influence Vav phosphorylation in T cells.

Human T cell leukemia virus I (HTLV-I) causes acute leukemic disease in a low percentage of infected individuals through obscure mechanisms. Our studies compare two rabbit HTLV-I-infected T cell lines: one, RH/K34, causes lethal experimental leukemia and the other, RH/K30, mediates asymptomatic infection. We show herein that the product of the protooncogene vav is constitutively Tyr-phosphorylated in RH/K34 but not in RH/K30. A role for the retrovirus in phosphorylation of Vav was assigned by transfection experiments with molecular clones of HTLV-I derived from the two lines. The HTLV-I molecular clone from RH/K30, but not that from RH/K34, down-regulates Vav phosphorylation in a Herpesvirus ateles-transformed T cell line. Use of recombinant virus clones revealed that a pX region sequence differing by two nucleotides between the two clones mediates this down-regulation. Because Vav is involved in T cell signaling and Vav phosphorylation occurs upon activation of T cells, control of the activation state of Vav by viral proteins may relate to the leukemogenic potential of certain HTLV-I-infected cells.

Cell-mediated HTLV-I infection of a cervix-derived epithelial cell line

There is considerable evidence that sexual transmission of human T-cell leukemia virus-I (HTLV-I) is mediated by virus-infected lymphocytes in genital tract secretions. However, it is not clear whether infection occurs through lesions in the genital tract epithelium or takes place via an intact epithelium. We have carried out experiments to test the hypothesis that sexual transmission of HTLV-I is initiated by lymphocyte-mediated infection of intact genital tract epithelia. To examine this question we added either free virus or HTLV-I producing MT-2 cells to cultures of a cervix-derived epithelial cell line, MS751. Although free virus did not infect MS751 cells, MS751 cells which had been coincubated with MT-2 cells became infected. These cultures produced about 50 pg/ml of HTLV-I p24 antigen per 106cells over a 24 h period on the sixth day following exposure to donor T-cells. Proviral DNA could be detected in target MS751 epithelial cells by PCR. Infection of epithelia could be blocked, in a dose-dependent manner, by the sulfated polysaccharides dextran sulfate, heparin, and fucoidan, and by the enzymes fucosidase and mannosidase, but not by a number of other agents that were tested. Since MT-2 cells were observed to attach to the epithelial monolayer, we examined the ability of agents to inhibit adhesion. Adherence was inhibited by the same agents that inhibited infection. Based on these findings, we hypothesize that sexual transmission of HTLV-I may involve lymphocyte-mediated infection of genital tract epithelia and that lymphocyte adhesion to the epithelium is a critical event in transmission of HTLV-I. We speculate that a sugar moiety on the epithelium, possibly mannose or fucose, may be involved in adhesion of T-cells to epithelial cells. As sulfated polysaccharides block both adhesion and productive infection of the epithelium, these compounds might be used as active ingredients in a vaginal formulation to help prevent HTLV-I transmission.

226 Search for human T-cell leukemia virus-I antibody in the people of northeast district of China

226 Search for human T-cell leukemia virus-I antibody in the people of northeast district of China

Family study of women showing development of antibody to human T-cell leukemia virus I and assessment of the risk of vertical transmission of the virus to their children

When pregnant women were tested for antibody to human T-cell leukemia virus-I, some were found to be positive although they had been negative during the previous pregnancy. In these women, HTLV-I infection was found from pedigree studies to have been acquired from their mothers rather than from their husbands. Furthermore, some of them had apparently remained HTLV-I antibody-negative for long periods after infection. When the breast-fed children of these women, in whom HTLV-I was acquired from their mothers but who were in an HTLV-I antibody-negative state, were also examined for evidence of HTLV-I infection, none was found.

Human soluble IL-6 receptor: its detection and enhanced release by HIV infection.

By using a fluorescence sandwich ELISA for the quantification of soluble human IL-6R, normal human PBMC were found to be induced to release IL-6R into culture supernatant by stimulation with PHA. Furthermore, certain promonocyte cell lines and human T-cell leukemia virus I (HTLV-I)-positive cell lines produced sIL-6R into culture supernatants constitutively. However, this was not found with HTLV-I negative T cell lines and Burkitt's B cell line. In addition, generation of supernatant IL-6R of the promonocyte cell line was significantly increased 27-fold after PMA treatment and sevenfold after infection with HIV. The released IL-6R molecules were characterized as an apparent m.w. of 50 to 55 kDa by both size-exclusion HPLC and immunoprecipitation of the soluble protein with IL-6R-specific mAb followed by SDS-PAGE analysis. Furthermore, increased levels of serum IL-6R were detected in blood donors seropositive for HIV. Moreover, the released IL-6R could bind efficiently to purified rIL-6 on solid phase and suppressed the proliferative responses of PBMC. These results suggest that the release of soluble IL-6R might be linked to regulatory functions of immune responses induced by IL-6 stimulation during normal and human retrovirus-infected cell growth and differentiation.

Examination of HTLV-I Integration in the Skin Lesions of Various Types of Adult T-Cell Leukemia (ATL): Independence of Cutaneous-Type ATL Confirmed by Southern Blot Analysis

The various clinical features of adult T-cell leukemia/lymphoma (ATL) are frequently accompanied by skin eruptions. Recently, a cutaneous type of ATL has been proposed by clinical studies. We analyzed the viral integration of human T-cell leukemia virus-I (HTLV-I) and monoclonal rearrangement of T-cell receptor (TCR) gene in blood lymphocytes and the cutaneous infiltrated cells of nine ATL patients with various clinical features and skin eruptions. We classified them by the results of Southern blot analysis and propose a cutaneous-type ATL accordingly. In two of them, we could detect the monoclonal integration of HTLV-I and T-cell monoclonality only in the skin but not in the peripheral lymphocytes. We also demonstrated the time course study in one patient. Clinicians should be aware of the HTLV-I positive cutaneous T cell lymphoma that can be named cutaneous-type ATL. Examination of viral integration and T-cell monoclonality in skin lesions is required to make an exact diagnosis of cutaneous ATL.