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Human thioredoxin (hTRX)/adult T-cell leukemia (ATL)-derived factor (ADF) was originally reported as an interleukin-2 (IL-2) receptor-alpha-inducing factor produced by human T-cell lymphotropic virus-1-positive (HTLV-1+) cell lines. Growing evidence indicates that hTRX/ADF plays important roles in cellular responses against oxidative stress and is involved in a variety of cellular functions. A high level of hTRX/ADF expression is also observed in other human virus-infected cell lines including those of Epstein-Barr virus (EBV) and human papillomavirus. In this report, we analyzed the effect of hTRX/ADF on lytic amplification and persistent replication of EBV as a model for lytic versus latent phase of viral replication in host cells. Addition of hTRX/ADF clearly suppressed lytic replication of EBV in Raji cells and B95-8 cells induced to the lytic phase of 12-O-tetradecanoylphorbol-13-acetate (TPA), and it prevented the death of these cells evoked by the lytic induction. In contrast, hTRX/ADF did not have any effect on persistent replication in the latent phase. These data indicated that hTRX/ADF prevents EBV-transformed cells from proceeding into the lytic phase and regulates cohabitation of EBV and its host cells.

Purpose: To evaluate the protective effects of recombinant adult T-cell leukemia- derived factor (ADF)-human thioredoxin against ischemia-reperfusion injury in the rat retina., Methods: Retinal ischemia was induced in rats by increasing the intraocular pressure to 110 mm Hg for 60 minutes. Various doses of recombinant human ADF (rhADF) or vehicle were administered intravenously before ischemia induction and immediately after reperfusion. The degree of retinal damage was assessed by electroretinogram (ERG) recording, by measuring the inner retinal thickness, and by counting the number of TdT-dUTP terminal nick-end labeling (TUNEL)-positive cells in the inner nuclear layer., Results: The amplitudes of the ERG b-wave and oscillatory potentials were increased significantly by treatment before ischemia and after reperfusion with 0.5 mg or 5 mg rhADF and by treatment after reperfusion with 1 mg rhADF, compared with those of vehicle-treated control rats (P < 0.01). On day 28 after reperfusion, the thickness of the inner retina of control rats and of rats treated before ischemia and after reperfusion with 0.5 mg rhADF were 46.1+/-6.4 microm and 78.5+/-8.9 microm, respectively (P < 0.01). The number of TUNEL-positive cells on days 1 and 2 after reperfusion was decreased significantly by treatments with 0.5 mg rhADF compared with the number of TUNEL-positive cells in control rats (P < 0.01)., Conclusions: Electrophysiologic and histologic studies showed that ischemia for 60 minutes produces severe damage in vehicle-treated control rat retina, particularly in the inner retinal layer. Intravenous injection of rhADF protects the rat retina from ischemia-reperfusion injury.

In both nonneurological and Alzheimer brains, we examined the localization of adult T cell leukemia-derived factor (ADF) by immunohistochemistry, that of its mRNA by in situ hybridization, and its semiquantitative mRNA analyses by RT-PCR. Anti-ADF antibody gave positive staining of white matter astrocytes and Schwann cells in the posterior root. Their intense and abundant staining was seen in Alzheimer brains. In situ hybridization for ADF mRNA showed identical signals in the white matter astrocytes. The evidence was also confirmed by RT-PCR analysis. These results suggest that redox regulation may play a role in Alzheimer pathology.

Adult T-cell leukemia-derived factor (ADF), originally defined as an interleukin-2 receptor inducer, is a human thioredoxin (TRX). ADF/TRX is a conserved multifunctional reductant presumably associated with redox regulation of the cellular environment; it works in vitro as a cytokine, free radical scavenger, activator of transcription factors, and substrate for several enzymes. In the present series of experiments, we studied the expression and intracellular localization of ADF/TRX in mouse kidney from two different renal tubular injury models: a free radical-associated model with ferric nitrilotriacetate (Fe-NTA) and a free radical-independent model with HgCl2. Markers of oxidative damage, such as 8-hydroxy-2'-deoxyguanosine, thiobarbituric acid-reactive substances, and 4-hydroxy-2-nonenal-modified proteins, were significantly increased in kidney from male C57B/6 mice 1 hour after a single intraperitoneal injection of Fe-NTA (5 mg iron/kg). However, in kidney from mice given a subcutaneous injection of HgCl2 (5 mg Hg/kg), none of these markers were increased, despite tubular necrosis with sulfhydryl depletion. In the Fe-NTA model only, Northern and Western blot analyses of the kidney revealed induction of ADF/TRX (> 2.5-fold) after 16 hours and translocation of ADF/TRX from the cytoplasmic to nuclear fraction (> 3.5-fold) after 24 hours. Immunohistochemistry showed a patchy distribution of ADF/TRX in the normal renal proximal tubules. In ex vivo experiments using serial normal kidney frozen sections, it was found that renal proximal tubules with low expression of ADF/TRX were more vulnerable to oxidative stress mediated by Fe-NTA. Collectively, these data suggest that: (a) ADF/TRX is induced and translocated to nuclei by oxidative damage mediated by Fe-NTA in the renal proximal tubules; (b) induction of ADF/TRX is independent of tubular necrosis or sulfhydryl depletion; and (c) ADF/TRX is involved in the cellular defense mechanisms in vivo against oxidative damage.

Thiol compounds, such as L-cysteine and glutathione (GSH), play crucial roles in the regulation of lymphocyte proliferation. In this study, we analyzed the effect of L-cystine and GSH depletion on lymphocyte survival and investigated the regulatory roles of adult T cell leukemia (ATL)-derived factor (ADF)/human thioredoxin (hTRX) in relation to these low m.w. thiols. MT-1, MT-2, and Jurkat cells underwent apoptosis when cultured in the L-cystine- and GSH-free medium within 18 to 24 h. Dichlorofluorescin oxidation assay indicated that the apoptosis in MT-1 and MT-2 cells was preceded by an increase in the level of intracellular hydrogen peroxide (H2O2). The addition of catalase and recombinant ADF/hTRX (rADF) partially blocked the apoptosis in a dose-dependent manner. rADF has been also shown to enhance the internalization of L-cystine into MT-2 cells in a dose-dependent manner, whereas oxidized rADF or mutated rADF that has no insulin-reducing activity failed to do so. Furthermore, culture in the L-cystine- and GSH-free medium lowered the cellular GSH content of PHA blasts, which was restored dose-dependently by rADF. These data suggest that the inability to neutralize oxidative stress results in the apoptosis of lymphoid cells under L-cystine- and GSH-depleted conditions. The protective effects of rADF may be explained by direct scavenging action on H2O2 (catalase-like activity) or by indirect neutralizing effects on the pro-oxidant status through enhancing the L-cystine internalization and elevating the intracellular GSH content.

Growing evidence has indicated that cellular reduction/oxidation (redox) status regulates various aspects of cellular function. Oxidative stress can elicit positive responses such as cellular proliferation or activation, as well as negative responses such as growth inhibition or cell death. Cellular redox status is maintained by intracellular redox-regulating molecules, including thioredoxin (TRX). TRX is a small multifunctional protein that has a redox-active disulfide/dithiol within the conserved active site sequence: Cys-Gly-Pro-Cys. Adult T cell leukemia-derived factor (ADF), which we originally defined as an IL-2 receptor alpha-chain/Tac inducer produced by human T cell lymphotrophic virus-I (HTLV-I)-transformed T cells, has been identified as human TRX. TRX/ADF is a stress-inducible protein secreted from cells. TRX/ADF has both intracellular and extracellular functions as one of the key regulators of signaling in the cellular responses against various stresses. Extracellularly, TRX/ADF shows a cytoprotective activity against oxidative stress-induced apoptosis and a growth-promoting effect as an autocrine growth factor. Intracellularly, TRX/ADF is involved in the regulation of protein-protein or protein-nucleic acid interactions through the reduction/oxidation of protein cysteine residues. For example, TRX/ADF translocates from the cytosol into the nucleus by a variety of cellular stresses, to regulate the expression of various genes through the redox factor-1 (Ref-1)/APEX. Further studies to clarify the regulatory roles of TRX/ADF and its target molecules may elucidate the intracellular signaling pathways in the responses against various stresses. The concept of "redox regulation" is emerging as an understanding of the novel mechanisms in the pathogenesis of several disorders, including viral infections, immunodeficiency, malignant transformation, and degenerative disease.

Thymic ID cells are involved in the differentiation of mature T cells which are resistant against apoptosis. TRX/ADF is a potent thiol-related reducing agent, acts as a redox regulator, and it can attenuate the induction of apoptosis of T lineage lymphocytes. In the present study, 42 thymoma-free thymus and 40 thymoma samples were examined to identify the expression of TRX/ADF in human thymic tissue. TRX/ADF high-producer (TRXh) cells with cytoplasmic protrusions were found distributed in the thymic medulla. These TRXh cells were negative for CD3, a lymphocyte marker, keratin, an epithelial cell marker, and CD68 or lysozyme, macrophage/monocyte markers, but were positive for S100 protein and HLA-DR complex. Our results revealed that the TRXh cells in the thymic medulla were ID cells. As TRX/ADF has an important and fundamental role in cellular responses acting against oxidative stress, TRX/ADF may provide an explanation of cellular interaction between the medullary ID cells and the mature T cells.

Prostaglandin E1 (PGE1) is commonly used in therapy for obstructive diseases, including ischemic retinopathy, in which pathogenetic reactive oxygen intermediates are responsible. However, the mechanism(s) of PGE1 in reducing tissue damage is still unclear. Adult T-cell leukemia-derived factor/human thioredoxin (ADF) is induced by oxidative stresses and has protective activity against oxidative cellular injury. To evaluate the possible involvement of ADF in the tissue-protective effect of PGE1, we analyzed ADF expression immunohistochemically using a rat transient retinal ischemia model. Rats were treated orally with 300 micrograms/kg/day OP-1206 alpha-cyclodextrin clathrate (OP-1206), a stable PGE1 analogue, for 14 days after photodynamic retinal vascular thrombosis by rose Bengal. Rats without any OP-1206 treatment were used as controls. In the OP-1206-treated rats, minimal retinal atrophy due to ischemia/reperfusion was observed histologically up to 14 days, whereas in the non-treated rats the inner layer of the retina became markedly atrophic. In parallel with the histological change, after 14 days following thrombosis ADF immunoreactivity was preserved on retinal pigment epithelial cells in the OP-1206-treated rats, whereas it was diminished in the non-treated rats. These findings suggest an important role for ADF in the OP-1206-dependent suppression of retinal tissue damage caused by oxidative insult.

Adult T-cell leukemia derived factor (ADF)/human thioredoxin (TRX), which has thiol reducing and radical scavenging activities, plays an essential role on cellular protection against oxidative stress and cell death. TRX itself is induced by various oxidative stress as well as the Human T-cell lymphotropic virus type I (HTLV-I) Tax protein. To investigate the mechanism of this induction, the promoter region of the TRX gene was analyzed. Chloramphenicol acetyltransferase (CAT) reporter constructs containing the TRX promoter sequences responded to the overexpression of the Tax protein, whereas various oxidative agents activated the TRX promoter through a newly identified oxidative responsive element. Moreover, TRX was translocated from the cytoplasm into the nucleus by ultraviolet irradiation, suggesting its possible role on sensing and transducing oxidative signals.

Adult T cell leukemia-derived factor (ADF) is a human thioredoxin (Trx) and is a disulfide reducing protein with various biological functions. We found that expression of the ADF/Trx gene was increased by oxidative agents such as hydrogen peroxide, diamide and menadione in Jurkat cells. Analysis using a CAT expression vector plasmid under the control of the ADF/Trx gene promoter revealed that CAT gene expression in Jurkat cells was increased after exposure to oxidative agents. A series of deletion analyses showed that a region from -976 to -890 of the 5' flanking sequence was required for enhancement of ADF/Trx promoter activity against the oxidative agents. Gel mobility shift assay revealed the specific DNA binding activities to the sequences from -953 to -930 in the nuclear extracts from the Jurkat cells. The sequences in this region showed no homology with any known consensus sequences for DNA binding factors. It is suggested that ADF/Trx gene expression is enhanced through a novel cis-acting regulatory element responsive for the oxidative stress and a new factor(s) is involved in this oxidative stress responsive element.

Objective: To determine the involvement of human thioredoxin/adult T cell leukemia-derived factor TRX/ADF) in Sjögren's syndrome (SS) and the correlation with Epstein-Barr virus (EBV)., Methods: Indirect immunohistochemical techniques and reverse transcriptase polymerase chain reaction were utilized to analyze TRX/ADF expression and the presence of EBV, using 6 normal tissues and 23 surgical specimens. The kinetics of expression of TRX/ADF induced by EBV was examined in vitro with peripheral blood B cells from EBV-seronegative donors., Results: Marked expression of TRX/ADF was found in the infiltrating B cells and the epithelial cells of salivary gland tissues from patients with SS (11 of 12 cases), but not in those from patients with other salivary gland inflammatory conditions (0 of 11 cases) or those of normal individuals (0 of 6 cases). In immunohistologic analyses, a striking topographic correlation between TRX/ADF and EBV was found. The coexistence of TRX/ADF messenger RNA and EBV DNA was detected by polymerase chain reaction (r = 0.75, P < 0.01). Peripheral blood B cells from EBV-seronegative donors showed de novo synthesis of TRX/ADF following in vitro infection with EBV. EBV-infected B cell lines all expressed TRX/ADF. TRX/ADF was not detected in non-EBV-infected cells. Tumors in SCID mice reconstituted with mononuclear cells of salivary glands from SS patients, which were composed of human B cells carrying EBV DNA, were positive for TRX/ADF., Conclusion: These findings suggest that TRX/ADF expression closely reflects the intracellular event of EBV reactivation in SS. This is also the first report to show the ectopic in vivo expression of TRX/ADF in human autoimmune disease.

Adult T cell leukemia-derived factor (ADF)/Thioredoxin (TRX), originally defined as an IL-2 receptor alpha-chain/p55 inducer, has many cytokine-like activities. We reported that the release of major basic protein (MBP) from mature eosinophils stimulated with cytochalasin B and C5a were augmented after preincubation with recombinant ADF/TRX. The addition of a TRX specific inhibitor, BE40644, suppressed the augmentation of MBP release from mature eosinophils. It is suggested that BE40644 is applicable in allergic diseases associated with eosinophils.

Lung transplantation is now an accepted therapeutic option for patients with end-stage lung disease, and an early diagnosis of rejection is essential in the management of these patients. Adult T-cell leukemia-derived factor (ADF), known as a human homolog of thioredoxin, has been shown to be induced by a variety of stresses. In this study we examined ADF expression in lung tissues and bronchoalveolar lavage cells after canine lung transplantation to determine whether it could be induced by allogenic stimulations and could be used to diagnose early rejection. Allotransplantations were performed in adult mongrel dogs, and immunosuppression was performed from the day of operation to the fifth postoperative day. No immunosuppressant was given from the sixth to the tenth postoperative days. Animals were put to death on the tenth postoperative day. Bronchoalveolar lavage was performed on the fifth and tenth postoperative days, and the lavage cells and lung tissues were examined immunohistochemically with anti-ADF antibody. The grades of rejection were as follows: grade 1 in two animals, grade 2 in three animals, and grade 3 in two animals. The percentages of ADF high-producer cells in bronchoalveolar lavage cells on the fifth and tenth postoperative days were 4.29% +/- 2.65% and 26.6% +/- 3.99%, respectively (p < 0.01). The percentages of ADF high-producer cells in normal healthy dogs and in those with grade 1, grade 2, and grade 3 rejection were 3.00% +/- 1.64%, 20.5% +/- 9.00%, 25.5% +/- 6.06%, and 34.5% +/- 6.50%, respectively. The percentage in each rejection group was significantly higher than that in normal healthy dogs (p < 0.05). These results suggest that examination of bronchoalveolar lavage cells with ADF staining may be useful in the early diagnosis of rejection.

Adult T-cell leukaemia-derived factor (ADF), homologous to thioredoxin, displays various biological activities, such as radical scavenging action and the reduction of protein disulphide bonds. We examined the biochemical and immunohistochemical localization of ADF in the pregnant human uterus, using two heteroantibodies to ADF, antibody C and W. Immunohistochemically, decidua and trophoblast cells were intensely stained by antibody C. The concentration of ADF-like substance in the decidua was 95.9 ng/mg protein, determined by enzyme-linked immunosorbent assay. The molecular weight of ADF-like substance in these tissues was determined by gel electrophoresis to be 13 kDa, the same as that of recombinant ADF. These findings indicate that abundant ADF is present in decidua and trophoblast cells; the localization of such a potent dithiol reducing substance may be beneficial in protecting the fertilized egg and placental trophoblasts from the cytotoxic effects of oxygen radicals.

Adult T cell leukemia-derived factor (ADF), which is identical to a disulfide reducing enzyme human thioredoxin (TRX), is produced and released by activated or virus-infected lymphocytes. Here we report that, in peripheral blood mononuclear cells (PBMC) stimulated with phytohemagglutinin (PHA), ADF/TRX mRNA was induced within 8 h after stimulation as detected by in situ hybridization study. To analyze the mechanism of ADF/TRX induction during T cell activation, the effects of immunosuppressants including FK506, rapamycin (Rap) and cyclosporin A (CsA) on ADF/TRX expression were investigated by immunoblot analysis. ADF/TRX induction in PBMC by PHA, Con A or OKT3 mAb was almost completely suppressed by FK506. Whereas CsA also inhibited ADF/TRX expression in OKT3 mAb-stimulated PBMC, Rap failed to affect it in spite of exhibiting growth inhibition. In addition, exogenous IL-2 could not increase ADF/TRX production in FK506-treated PBMC or in PHA blasts. These results indicate that ADF/TRX induction in T cell activation depends on calcineurin-dependent events in the early phase and that IL-2 production is not directly involved in ADF/TRX induction. Furthermore, when recombinant ADF (rADF) was added to a culture of PBMC 1 h before the addition of PHA and FK506, the action of FK506 was partially reversed as determined by [3H]thymidine incorporation and viable cell counts. These results suggest that ADF/TRX produced and released from PBMC may be a crucial event in lymphocyte activation, and that FK506 and CsA may exert the immune suppression partly through inhibiting the induction of the endogenous reducing factor ADF/TRX.

The relationship between the expression of adult T-cell leukemia-derived factor, human thioredoxin (ADF/TRX), and rejection in transplanted canine lungs was investigated in this study. Of a total 27 adult mongrel dogs, 24 underwent allotransplantation of the left lung with no immunosuppressant and the other three underwent autotransplantation of the left lung. Of the allotransplanted dogs, five were killed on postoperative day (POD) 1, five on POD 2, seven on POD 3, and seven on POD 5, while all three autotransplanted dogs were killed on POD 5. Histological examination was performed on the 24 allotransplanted left lungs (group A), 12 autologous right lungs (group B), and bilateral lungs of the three autotransplanted dogs (group C). The lung tissue was stained with anti-ADF antibody, and the high-ADF-producing cells (ADFh cells) in a randomly chosen field were counted as an index of ADF expression. As the signs of rejection in the group A lungs became more severe with time, the ADFh cells increased in number: 1.68 +/- 1.15, 6.08 +/- 3.44, 14.03 +/- 6.09, and 47.74 +/- 18.89, on PODs 1, 2, 3, and 5, respectively. However, the number of ADFh cells in the group B and group C lungs did not become significantly different from that on POD 1 in group A. These results suggested that ADF/TRX expression may be useful for the early diagnosis of rejection of transplanted lungs.

Adult T-cell leukemia-derived factor (ADF)/human thioredoxin (TRX) has thiol-dependent reducing activities and is known to have regulatory roles on the DNA-protein interaction and cell activation. Inducive effect of ultraviolet (UV) has been indicated because of the enhanced expression of ADF/TRX in epidermal cells of sun-exposed skin, as determined by immunohistochemical staining with antibody against recombinant ADF (rADF). We studied the effect of UVB irradiation and other oxidative stress on the expression of ADF/TRX in epithelial cells as well as lymphoid cells, as HTLV-1 and Epstein-Barr virus-transformed lymphoid cells constitutively produce ADF/TRX. Using immunohistochemical staining anti-ADF antibody, the enhancement of ADF/TRX expression on primary culture of human keratinocytes was demonstrated, 12 h after 20 mJ/cm2 UVB irradiation. Western blot analysis of the ADF/TRX protein in the cell lysates also showed the significant induction. In in situ hybridization, induction of ADF/TRX mRNA was detected after 4 h of UV exposure. ADF/TRX was also induced in a HTLV-1 (+) T-cell line, MT-1, by UVB or H2O2 dose dependently. The augmentation of ADF/TRX was observed 6 h after treatment of H2O2.

Adult T cell leukemia-derived factor (ADF), originally defined as an interleukin 2 receptor/alpha (alpha) chain inducer produced by human T-lymphotropic virus type-I transformed cells, is identical to human thioredoxin (TRX). In this study, the protective effect of ADF/TRX on the cytotoxicity of endothelial cells caused by phorbol myristate acetate (PMA)-activated neutrophils or hydrogen peroxide (H2O2) was examined. When murine endothelial F-2 cells established from an ultraviolet light-induced tumor on a nude mouse were incubated with PMA-activated neutrophils or with 1 mM H2O2 for 6 hours, the cytotoxicity of F-2 cells was respectively 51 +/- 4% or 40 +/- 8% by the 51Cr releasing assay. Recombinant ADF/TRX (rADF/TRX) inhibited this cytotoxicity in a dose-dependent manner, although mutant ADF/TRX (cysteine 31 to serine), 2-mercaptoethanol and dithiothreitol did not. On a molar basis, rADF/TRX was more effective than glutathione but less effective than catalase. Immunoblotting analysis showed that treatment with 0.1 mM H2O2 induced murine TRX on F-2 cells. These findings indicate that ADF/TRX is an oxidative stress-inducible endogenous protein and rADF/TRX plays a protective role against activated neutrophils- or H2O2-induced endothelial cytotoxicity.

Adult T cell leukemia-derived factor (ADF) is a human homologue of thioredoxin (TRX) with many biological functions and is induced by various stimuli and stress. In the central nervous system (CNS), expression of ADF/TRX occurs in glial cells during ischemia and reperfusion. We showed that ADF/TRX was actively released from U251 astrocytoma cells upon exposure to a low concentration of H2O2. The addition of conditioned medium from H2O2-stimulated U251 cells or recombinant ADF (rADF) to the culture medium promoted the survival of neurons from embryonic mouse cortex and striatum, but the addition of mutant ADF (mADF), which has no reducing activity, did not. In addition to rADF, incubation with two other thiol compounds, 2-mercaptoethanol (2-ME) and N-acetyl-L-cysteine (NAC), also increased the neuronal cell survival rate. In contrast, L-buthionine-(S,R)-sulfoximine (BSO), which inhibited the synthesis of glutathione (GSH), decreased the neuronal cell survival rate. Intracellular GSH was increased by incubation with rADF for 24 h, as it is with 2-ME and NAC. Redox active molecules such as thiol compounds may be survival factors for central neurons in vitro, and this capacity may be supplied by endogenous molecules, such as ADF/TRX and glutathione, under certain pathologic conditions in vivo.

The adult T cell leukemia (ATL)-derived factor (ADF) was first described as an interleukin 2 receptor alpha chain (IL-2R alpha) inducing factor which is produced by an HTLV-I infected cell line. Subsequent purification and gene cloning proved that it is a human homologue of a bacterial reducing coenzyme, thioredoxin (TRX). ADF/human TRX (hTRX) has multiple functions both in the extracellular and intracellular compartments, such as cytokine activity, dithiol-reducing activity and radical scavenging activity. ADF/hTRX can facilitate the interactions between the transcriptional factors and its target DNA sequences, which may result in the overexpression of IL -2R alpha in HTLV-I infected cells. Recently, we have detected the presence of ADF/hTRX in human serum (sADF) obtained from healthy volunteers using the insulin reducing assay and Western blotting analysis. Another endogenous redox regulator, glutathione (GSH) system, has long been studied for its relation to cell proliferation and activation. Our recent data showed that thiol compounds such as L-cysteine and GSH may be involved in the activation and cell cycle progression of stimulated lymphocytes. We have also found that ADF/hTRX promotes L-cysteine transport into the cells and increases intracellular GSH content, indicating the close association between ADF/hTRX and GSH systems. Redox regulation by ADF/hTRX and GSH systems seems to play an important role in regulating cell proliferation and activation. To assess the possible alteration of the sADF level in pathological conditions, such as viral infections, an ELISA system for ADF/hTRX was recently established using two different monoclonal antibodies against rADF.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult T-cell leukemia (ATL)-derived factor (ADF), originally defined as an inducer of interleukin-2 receptor/alpha-chain (IL-2R/p55) of human T-lymphotropic virus type I (HTLV-I) positive T cells, is a human homologue of redox-active coenzyme thioredoxin (Trx) of Escherichia coli. In this study, an enzymatic assay system based on the dithiol-dependent insulin-reducing activity of ADF/Trx was established (insulin-reducing assay) to determine the amount of ADF/Trx in human serum using NADPH and Trx reductase purified from human placenta. Insulin-reducing activity was detected in all of the serum samples from healthy volunteers (n = 30) screened by this assay, with a mean +/- SD of 10.9 +/- 2.4 U/l. This mean value corresponds with the concentration of 223 ng recombinant ADF/Trx (rADF/Trx)/ml. Human serum is known to contain several redox-active proteins with ADF/Trx motifs. To differentiate the contribution of these proteins and ADF/Trx to the insulin-reducing activity, the anti-rADF/Trx monoclonal antibody (mAb)-conjugated affinity column-depleted sera obtained from an identical source was used for analysis. The affinity column-depleted sera demonstrated a loss of over 99% of the original activity, while control column depleted sera lost less than 4%. Furthermore, the amount of affinity-purified ADF/Trx molecules eluted from the same column almost corresponded with the amount estimated by the insulin-reducing activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Purpose: Adult T cell leukemia derived factor (ADF) is a human homologue of thioredoxin (hTx), which exhibits scavenging activity with reactive oxygen intermediates. In their previous study, the authors found that after transient retinal ischemia, the expression of thioredoxin in rat retinal pigment epithelium (RPE) layer increased markedly. The present investigation is to determine intracellular ADF localization in RPE after transient ischemia and in cultured human RPE cells after oxidative insult by H2O2., Methods: The authors employed immunoelectron microscopy to examine ADF localization in RPE. Labeling density analysis was performed to supplement the main observation in the experiment of transient retinal ischemia. 3-(4,5-dimethylthiazol-2yl)-2-5-diphenyltetrazolium bromide (MTT) assay was performed to verify the protective role of recombinant ADF (rADF) against H2O2., Results: In immunogold electron microscopy, sparse ADF-positive labeling was seen in the cytosol and mitochondria in normal rat RPE and in untreated cultured RPE cells. After oxidative stress, it was concentrated in mitochondria in both groups. MTT assay proved that rADF protected cultured RPE from the toxicity of H2O2., Conclusions: This study shows the induction of ADF/hTx in mitochondria of RPE after oxidative stresses and its protective effect on cultured RPE exposed to H2O2. The data indicate the possibly important role of ADF/hTx in the protection of retinal cells from the oxidative stresses associated with retinal ischemic disease and probably with regular visual activity.

Background: Adult T cell leukemia derived factor (ADF), originally defined as an interleukin-2 receptor inducer, is a human thioredoxin homolog. ADF/thioredoxin has several biologic functions, such as defense against cellular damage, activity to scavenge oxidative stress by hydrogen peroxide radicals and cytokine-like properties. We hypothesized that under certain conditions, ischemia followed by reperfusion and/or light exposure, ADF may be induced in the retina., Experimental Design: To test this hypothesis, we prepared experimental animal models in which oxidative stress could be applied to the retina. In the present study, we examined ADF expression in the rat retina using temporary ischemia and reperfusion, and photodynamic retinal vascular thrombosis by immunohistochemical and Western blotting methods., Results: ADF expression was strongly induced in the retinal pigment epithelial cells after 2 hours of ischemia followed by 2, 24, or 48 hours of reperfusion. ADF was also expressed in retinal pigment epithelial cells as early as 3 hours after light exposure followed by rose bengal injection, and this expression increased with time. Western blotting data showed that ADF expression increased in the retinal pigment epithelial cells in the experimental group, as compared with the control group. These results indicate that ADF is actively induced in retinal pigment epithelial cells upon oxidative stress., Conclusions: ADF induction in retinal pigment epithelial cells may be involved in the defense mechanism against cellular damage caused by active oxygen species generated during oxygen stress to the retina.

Adult T cell leukemia-derived factor (ADF), originally defined as an IL-2 receptor alpha-chain (IL-2R alpha)/p55 (Tac) inducer, is a human thioredoxin homologue and has many cytokine-like activities. In this study, we examined the regulatory effect of ADF on eosinophil migration using human eosinophils and an eosinophilic subline of HL-60 human promyelocytic leukemia cells, YY-1. rADF induced migration of eosinophils from patients with hypereosinophilia, although rADF exhibited little activity on eosinophils from healthy donors. When human eosinophils were incubated with rADF (0.1-10 micrograms/ml) at 37 degrees C for 24 h, both chemotactic and chemokinetic activity of the complement anaphylatoxin peptide C5a on eosinophil migration was markedly enhanced in a dose-dependent manner. Similarly, this enhancing effect of rADF was observed in the migration assay using YY-1 cells. In contrast, rADF showed no modulation of migratory behavior of human eosinophils and YY-1 cells by IL-3, IL-5, nor granulocyte-macrophage colony-stimulating factor. Scatchard analysis of C5a receptors on YY-1 cells using 125I-C5a showed that rADF modulated neither the density nor the affinity of the cell membrane significantly. Furthermore, mutant ADF (mADF), which had no reducing activity, had no enhancing effect on C5a-induced eosinophil migration. These results indicate a possible involvement of ADF in the recruitment of eosinophils through redox regulation by a dithiol reductase activity.

Distribution of adult T cell leukemia derived factor (ADF/TRX), a human thioredoxin homologue, was studied by immunohistochemistry in gerbil brain during reperfusion after transient cerebral ischemia. In control brains, immunoreactivity was observed widely in the central nervous system, including the ependyma, tanycytes, endothelial cells as well as subcommisural organs, and weakly in the neuronal cell bodies. During reperfusion, ADF/TRX was expressed in glial cells in the CA1 and dentate hilus of the hippocampus, and in a few cases in the lateral portion of the caudateputamen. ADF/TRX positive glias first appeared after reperfusion for 24 h, and the intensity of staining peaked at 72 h and diminished after 7 days of reperfusion. They were concentrated around microvessels and identified to be astroglia by double labeling immunohistochemistry with glial fibrillary acidic protein as marker. Immunoblotting analysis demonstrated an increase of ADF/TRX in the postischemic hippocampus. Astroglial expression of ADF/TRX in postischemic injuries suggests a role in neuroprotection by hydrogen peroxide reducing and protein-refolding activities or in modulation of local immune responses.

Reducing and protein-refolding activities of adult T cell leukemia-derived factor (ADF)/human thioredoxin were studied. Recombinant ADF/human thioredoxin produced by E. coli, which has an insulin-reducing activity as efficient as that of E. coli thioredoxin, also reduced some reactive oxygen species, such as hydrogen peroxide. Furthermore, recombinant ADF/human thioredoxin was found to have protein-refolding activity for scrambled (mispaired disulfide-containing) RNase A. Cys-31 at the active site of ADF/human thioredoxin proved essential for reducing activity, and loss of Cys-31 in ADF/human thioredoxin attenuated the protein-refolding activity. These data suggest a physiological role of ADF/human thioredoxin in protecting living cells from proteotoxicity caused by reactive oxygens in vivo.

Adult T-cell leukaemia (ATL)-derived factor (ADF), originally described as an inducer of interleukin-2 receptor-alpha (IL-2R alpha/Tac), has homology with the co-enzyme thioredoxin which is involved in many dithiol-dependent reducing processes. Using antibody against the C-terminal synthetic polypeptide of ADF and RNA probe of ADF, we examined the expression of ADF in various cell lines by immunofluorescence, immunohistochemical staining, Western blotting and in situ hybridization. ADF was intensely expressed on HTLV-I+ T-cell lines as compared with HTLV-I- T-cell lines. While the Epstein-Barr virus (EBV)+ B-lymphoblastoid cell lines were intensely positive for ADF, Burkitt-derived B cell line Jijoye with defective EBV was negative for ADF. Electron microscopic and photomicroscopic analysis of HTLV-I+ ATL-2 cells showed that ADF was localized on both the cell membrane and cytosol. In ATL-2 cells, a marked heterogeneity of ADF expression was observed. In in situ hybridization, heterogeneity of ADF messenger RNA (mRNA) expression was also demonstrated, indicating that ADF expression was regulated in the transcriptional level.

The regulation of low-affinity Fc receptor for IgE (Fc epsilon RII) and the characteristics of both membrane and soluble forms of Fc epsilon RII were studied using YT cell line. We found that YT cells, a human NK like cell line, expressed Fc epsilon RII after IL-1 stimulation. Cross-linking of Fc epsilon RII on IL-1-stimulated YT cells as well as the transfectant of Fc epsilon RII-cDNA (YTSER) resulted in the up-regulation of IL-2R alpha (p55/Tac). A 59 kDa protein phosphorylated at tyrosine residues was co-immunoprecipitated with Fc epsilon RII from YTSER lysate using H107 anti-Fc epsilon RII mAb. YTSER not only expressed Fc epsilon RII on their surface but also secreted soluble form of Fc epsilon RII (sFc epsilon RII/sCD23; IgE binding factor). Affinity purification revealed that sFc epsilon RII released from YTSER is heterogeneous and consisted of several proteins differing in molecular weight. Both EBV+ B cells and HTLV-1+ T cells are high producers of ATL derived factor (ADF)/thioredoxin (TRX) and express Fc epsilon RII and IL-2R alpha respectively. To clarify the mechanism of Fc epsilon RII and IL-2R alpha induction by ADF/TRX, we examined the effect of ADF/TRX on the bindability of nuclear factor kappa B (NF-kappa B), which is known to regulate IL-2R alpha gene expression. In the gel shift assay, ADF/TRX was shown to enhance the bindability of NF-kappa B to its responsive element.

Transcription from the human immunodeficiency virus type 1 (HIV-1) provirus is activated by a cellular factor, NF kappa B, recognizing the tandemly repeated 10-base-pair sequences, termed the kappa B sequence, present in the enhancer region within the viral long terminal repeat (LTR). Using electrophoretic mobility shift assay (EMSA), which demonstrates specific DNA-protein interaction in vitro, we could demonstrate that reducto-oxidative modulation of NF kappa B dramatically changes its DNA binding activity and that a cellular physiological reducing catalyst, thioredoxin (TRX) also known as adult T cell leukemia derived factor (ADF), fully restored the DNA-binding activity of the oxidized NF kappa B. We also observed that purified TRX/ADF protein could augment gene expression from HIV LTR as demonstrated by transient chloramphenicol acetyltransferase (CAT) assay. These observations confirmed the previous notion that ADF might be an inducing factor of cellular interleukin-2 receptor alpha subunit (IL-2R alpha) through the kappa B sequence that is a common central cis-regulatory element in both IL-2R alpha and HIV gene expression. These observations indicate that reducto-oxidative regulation (or redox regulation) of a cysteine residue(s) on the NF kappa B molecule might play an important role in its specific DNA interaction and that it might provide a clue to the understanding of a pathway of cellular signal transduction to NF kappa B that is independent from the known pathways involving protein phosphorylation.

Adult T-cell leukemia-derived factor (ADF), originally defined as an interleukin-2 receptor inducer, is a human thioredoxin homologue. ADF is detected in many malignant tissues and has a growth-promoting effect on transformed cells. In this study, ADF expression was examined immunohistochemically in human liver cell lines and liver tissues, and its growth-promoting effect was tested on human hepatoma cells. On three liver cell line--PLC/PRF/5, HepG2, and Chang liver cells--ADF stained positively and also was detected by immunoblotting. ADF had strong staining in the fetal liver (n = 8), although it was faint in the normal adult liver (n = 6). In hepatocellular carcinoma (n = 25), ADF expression generally was enhanced and was very strong in 52% (13 of 25) of the cases, although it was moderate in cases of chronic hepatitis or cirrhosis. ADF augmented the growth of PLC/PRF/5 cells and showed an additive effect with epidermal growth factor. These results indicate possible involvement of ADF in cell activation and growth of hepatocytes, as is the case with lymphocytes.

ADF (adult T-cell leukemia-derived factor), originally defined as an inducer of interleukin 2 receptor/alpha (IL-2R/alpha), is a homologue of thioredoxin. ADF is constitutively produced by human lymphoid cell lines transformed by human T-lymphotropic virus type I (HTLV-I) or Epstein-Barr virus (EBV). ADF augments the proliferation of HTLV-I and EBV transformed cells as an autocrine growth factor. These data are indicative of the possible involvement of ADF in virus-related transformation of cells and their autocrine growth. On the other hand, thioredoxin contains a redox active disulfide and has a reducing activity in the presence of thioredoxin reductase and NADPH. To clarify the role of ADF/thioredoxin system in the viral transformation, we tested the effect of 13-cis-retinoic acid (RA), which is a competitive inhibitor of thioredoxin reductase, on the growth of ADF high producing cells. The expression of IL-2R/alpha on HTLV-I (+) cells was suppressed by RA. RA dose-dependently reduced the cell number and viability of ADF high producing lymphoid cells. Moreover, it had a suppressive effect on the proliferation of ADF high producing cells. It is suggested that RA has an inhibitory effect on the activation and the growth of cells producing ADF and that inhibition of the ADF/thioredoxin system may be a new therapeutic approach for retrovirus-related disorders.

An immunohistochemical study of the expression of adult T-cell leukaemia-derived factor (ADF), a human thioredoxin homologue, was performed in the normal human ovary throughout the menstrual cycle. Primordial follicles were negative for ADF. Both granulosa cells and theca interna cells at the stages of preantral and antral follicles contained ADF. The staining intensity of these cells was very strong in the preovulatory dominant follicle. After ovulation, both granulo-lutein and theca-lutein cells were positive for ADF. During pregnancy, the theca-lutein cells revealed very intense ADF staining. The theca interna cells of the atretic follicles showed ADF staining, while the granulosa cells of such follicles did not. These results suggest that ADF localizes in the ovarian steroidogenic cells which have the binding sites of either luteinizing hormone or follicle-stimulating hormone, and that ADF expression is closely associated with the activity of the ovarian steroidogenic cells.

Adult T cell leukemia-derived factor (ADF) is a human homologue of thioredoxin with many biologic functions including IL-2R induction, growth promotion, thiol-dependent reducing activity, and radical scavenging activity. The regulatory effect of ADF on the cytotoxic activity of TNF was examined by using a human histiocytic lymphoma cell line, U937. When U937 cells were preincubated with recombinant ADF (rADF) (0.1-100 micrograms/ml) at 37 degrees C for 30 min, TNF-dependent cytotoxicity on U937 cells was markedly inhibited. This inhibitory effect was as high as 95% in the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay (rADF 100 micrograms/ml) and 85% in the 51Cr-releasing assay (rADF 10 micrograms/ml). After pretreatment of U937 cells with IFN-gamma to augment the sensitivity to TNF, an inhibitory effect of rADF was also found. When U937 cells were washed after preincubation with rADF, resistance to TNF-dependent cytotoxicity was still observed, indicating that rADF inhibited the sensitivity of U937 to TNF-dependent cytotoxicity rather than modifying TNF molecules. Scatchard analysis of TNF receptors on U937 cells using 125I-TNF showed that rADF modulated neither the density nor the affinity of the cell membrane significantly. rADF also reduced the cytotoxicity induced by anti-Fas IgM mAb which shows cytotoxicity quite similar to TNF. rADF (10 micrograms/ml) reduced 90% of the cytotoxicity by anti-Fas IgM mAb, without a detectable change either in Fas Ag expression (MFI 58.1 vs 53.3) or in the degradation of anti-Fas IgM mAb as determined by flow cytometric analysis. These findings indicated that the rADF-induced resistance to the cytotoxic effect of TNF and anti-Fas mAb was not related to the modulation of the TNF receptor or Fas Ag.

Adult T-cell leukemia-derived factor (ADF) is an autocrine interleukin-2 receptor-inducing factor produced by human T-lymphotropic virus-1 (HTLV-1)-transformed lymphocytes, which has a high structural homology with an endogenous dithiol reducing coenzyme, thioredoxin. Its localization was investigated immunohistochemically in the cervix, using normal tissue (27 samples) and squamous neoplastic tissue (three condylomas, 42 cervical intraepithelial neoplasia [CIN] samples, 34 invasive squamous cell carcinoma samples). The expression of human papillomavirus (HPV) DNA was also studied in serial sections of the same subjects. Normal squamous cells and glandular cells of the cervix were negative for ADF. However, intracytoplasmic and/or intranuclear ADF-positive cells were usually found in the intermediate and superficial layers of the neoplastic squamous epithelium of condylomas (three of three cases) and CIN (35/42 cases). HPV DNA was detected in all condylomas and in 27 of 42 CIN specimens. HPV DNA-positive cells were usually localized in the intermediate and superficial layers of the neoplastic squamous epithelium. These HPV DNA-positive cells were also positive for ADF. Invasive squamous cell carcinoma was also positive for ADF (24/34 cases) and HPV DNA (11/34 cases). The coexpression of HPV DNA and ADF was observed in all HPV DNA-positive cases. Coexistence of HPV DNA and ADF immunopositivity in neoplastic squamous cells of the cervix suggests that ADF expression closely reflects the intracellular event on HPV DNA replication.

To examine the distribution of adult T cell leukemia derived factor (ADF) in oral epithelial lesions, an immunohistochemical method using a polyclonal antibody against ADF C-terminal peptide was applied to formalin fixed and paraffin embedded tissues. All cases of periodontitis, epithelial hyperplasia, epithelial dysplasia and leukoplakia examined stained positively for ADF. Immunoreactive products were localized in the cytoplasm and/or nucleus of spinous and parakeratotic layers, but not in basal and keratinous layers. In addition, five out of nine papillomas stained positively for ADF, especially in koilocytotic cells. Eight out of 13 squamous cell carcinomas stained positively. Furthermore, ADF positive areas in oral epithelial lesions were included in the areas for protein bound SH-groups. Our results suggested that ADF may be a factor involved in the differentiation and proliferation of stratified squamous epithelium of the oral cavity.

A human T cell leukemia virus-I infected T cell line, ATL-2, produces an interleukin-2 receptor inducing factor, adult T cell leukemia (ATL)-derived factor (ADF). In the conditioned medium (CM) of ATL-2, we found an inhibitory activity on the epidermal growth factor (EGF)-dependent proliferation of primary cultured rat hepatocytes, measured by cell number and [3H]thymidine incorporation. ATL-2 CM dose-dependently inhibited hepatocyte proliferation. This activity was fractionated by gel filtration at a molecular size of 15,000 to 40,000 and was tentatively called hepatocyte growth inhibitory factor (HGI). Further fractionation with the ion-exchange column indicated that HGI was separable from ADF. Nevertheless, there was a positive correlation between HGI and ADF production, because the HGI activity was also detected in the CM of another ADF producer cell line (HUT102), while no significant HGI activity was detected in the CM of low ADF producer cell lines, ED and MOLT4.

An immunohistochemical study of the expression of adult T-cell leukaemia-derived factor (ADF), a human thioredoxin homologue, was performed using a rabbit antibody against the C-terminal peptides of ADF. Tissues were obtained from human fetuses between 9 and 23 weeks of gestation. It was revealed that ADF was widely distributed in different organs and tissues during the fetal period. The ADF antibody reacted selectively with medullary cells of the thymus, lung epithelium, the epithelium of the digestive tract, hepatocytes, bladder epithelium, peripheral nerve cells, hair follicles, sebaceous glands, osteoblasts and the proximal tubules of the kidney. It also reacted with cells destined to differentiate into ciliated cells in the fallopian tube and efferent ductules of the testis, interstitial cells in the ovary, Leydig cells of the testis, and dendritic cells in the spleen and lymph nodes. This is the first report on the thioredoxin system in human cells during the early fetal period. The selectivity of ADF staining in fetal tissues suggests that, during early fetal life, ADF expression correlates well with the cellular function of certain tissues.

HTLV-I transformed T cells not only express a large number of interleukin-2 receptors (IL-2R/p55(Tac], but also produce an IL-2R/Tac inducer named ATL-derived factor (ADF). We have cloned the ADF cDNA and found that ADF production in human lymphocytes can be enhanced by cellular activators such as mitogens or phorbol esters. Recombinant ADF produced by E. coli was shown to have growth-promoting activity in combination with interleukin-2 or suboptimal mitogenic stimuli on several lymphoid cells including human PBMCs, besides the originally reported IL-2R/Tac inducing activity. Homology analysis revealed an unexpected structural relationship between ADF and dithiol-reducing enzyme, thioredoxin, which had been characterized originally in prokaryotic system. Recombinant ADF also has a reducing activity, suggesting the presence of still unknown features of ADF action in vivo. The requirement of dithiol reduction in the biological activities of ADF, together with the possible involvement of ADF production in the normal and abnormal activation of human cells are discussed.

Interleukin 1 (IL-1) has been obtained from the Epstein-Barr virus-infected B-lymphoblastoid cell line 3B6 and shown to be involved in autocrine growth of 3B6 B cells. Independently, adult T-cell leukemia-derived factor (ADF) was purified from human T-lymphotropic virus I-infected leukemic T-cell line (ATL-2) and reported as an interleukin 2 (IL-2) receptor-inducing factor. We have previously reported the same molecular mass, pI, and NH2-terminal amino acid sequence for both 3B6-derived IL-1 and ADF. cDNA cloning of ADF demonstrated high homology with the prokaryotic disulfide reducing enzyme thioredoxin. We show here that ADF and 3B6-derived IL-1 are identical. By RNA blot, 3B6 and ATL-2 cells were shown to contain high levels of 0.6-kilobase mRNA corresponding to ADF. Such message was not detected in resting peripheral blood lymphocytes but could be weakly induced by lymphocyte activation. Antibodies have been raised against synthetic peptides corresponding to the NH2 terminus and the COOH terminus of ADF. Immunoblotting and sequential immunoprecipitation with these antibodies revealed the same 13-kDa protein in 3B6 and ATL-2 cells. Recombinant ADF could sustain growth of 3B6 and ATL-2 cells at low cellular concentration without fetal calf serum; ADF, thus, appears involved in their autocrine growth. Similarly, recombinant ADF could enhance growth of other B-cell lines, including the Epstein-Barr virus-negative Burkitt lymphoma line BL41 and the lymphoblastoid cell lines CRAG8, CRB95, and 1G8. Finally, recombinant ADF exhibits marked synergism with other cytokines, such as IL-1 and IL-2, allowing virally infected lymphocytes to respond to suboptimal amounts of a variety of growth factors.

Lymphocyte transformation/activation is accompanied by the induction of a variety of the inducible receptors associated with the activation antigens. The p55 chain of the interleukin-2 receptor (IL-2R/p55) recognized by anti-Tac monoclonal antibody (mAb) is expressed on activated T and B cells as well as natural killer (NK) cells. IL-2R/p55(Tac) is constitutively expressed on T4(+) T cells transformed by human T-lymphotropic virus I (HTLV-I), which is a causative agent for adult T-cell leukemia (ATL). Low affinity Fc receptor for IgE (Fc epsilon R2/CD23) is another inducible receptor binding IgE and is expressed on various hematopoietic cell types. While the physiological expression of Fc epsilon R2 and its soluble form (IgE Binding Factor; IgE BF) is variably regulated by cytokines and IgE, there is a constitutive expression of Fc epsilon R2 on Epstein-Barr virus (EBV) transformed B cell lines and some of HTLV-I (+) T cell lines. ATL-derived factor (ADF) has been characterized as an IL-2R/p55(Tac) inducing factor derived from HTLV-I(+) T cell lines. Purification of ADF protein and the cDNA cloning proved that ADF is closely related to the autocrine growth factor produced by an EBV(+) B cell line 3B6 (H. Wakasugi and T. Tursz) and belonging to the family of thiol reducing co-enzyme thioredoxin which is involved in many biological reactions. Recombinant ADF produced by COS cells and E. coli showed both IL-2R inducing and reducing activities. We will discuss the biological roles of ADF in viral and normal lymphocyte activation and transformation in relation to the receptor gene activation.

Human T-cell leukemia virus (HTLV)-infected cell lines derived from adult T-cell leukemia (ATL) express constitutively the receptor for Interleukin-2 (IL-2-R) and the associated antigen (Tac antigen). In contrast, the same antigen is transiently expressed by normal T-cells only after immune stimulation. Recently, it was reported that the constitutively expressed Tac antigen on ATL cells and cell lines was not down-regulated or modulated by anti-Tac antibody. Since the antigen was modulated on normal mitogen- or alloantigen-stimulated T-cells, we postulated that the regulation of IL-2-R may be abnormal on ATL cells; the synthesis of IL-2-R is continuously stimulated in these cells. A unique HTLV/ATLV(-) cell line (YT) derived from a child with acute lymphoblastic leukemia was found to express low levels of Tac antigen that could be enhanced by various stimuli, including conditioned medium (CM) derived from normal lymphocytes, but not by lectins (PHA, Con A). Of particular interest, the exposure of YT cells to CM from ATL cell lines with helper phenotype revealed the presence of factor(s) (ATL-derived factor, ADF) that augmented the synthesis and expression of IL-2-R/Tac antigen on YT cells and promoted YT cell growth. CM from HTLV(-) leukemia cell lines lacked both IL-2-R augmenting activity and a growth promoting activity. Immunoaffinity-purified IL-2 and recombinant gamma interferon also lacked IL-2-R augmenting activity. Moreover, the physicochemical analysis with Fast protein liquid chromatography (FPLC) revealed that ADF was quite different in pI point from the IL-2-R augmenting activity in CM from normal lymphocytes. These results suggested that ADF is a unique product of HTLV(+) cells. The possible relationship between ADF production, HTLV infection, and the abnormal expression of IL-2-R is suggested, and these abnormalities may be advantageous for the leukemogenesis and abnormal growth of ATL.

Many human T cell lymphotropic virus-I (HTLV-I) transformed T cells from adult T cell leukemia (ATL) patients continuously produce a humoral factor called ATL-derived factor (ADF) which induces IL-2R/Tac expression on T and NK cells. Using gel filtration, procion red Sepharose, DEAE, and reverse phase chromatography, we have purified ADF protein to homogeneity from 15 liters of serum-free culture supernatant of an HTLV-I(+) T cell line ATL-2. Purified ADF protein had the m.w. of 14,000 by SDS-PAGE and gel filtration, and its isoelectric point is around 5.0. ADF did not react with heteroantibodies against IL-1 alpha and IL-1 beta, which have also IL-2R/Tac-inducing activity on suitable target cells. Partial N-terminal amino acid sequence of ADF is different from other cytokines such as, IFN, BSF-2, and various IL whose cDNA has been cloned. Western blot analysis using rabbit antibodies against N-terminal 10mer synthetic peptide of ADF showed that IL-1 alpha and ADF are different proteins. ADF had its IL-2R/Tac-inducing activity not only on human NK-like cell line YT, but also on HTLV-I(+) T cells, such as ED. In contrast, macrophage-derived IL-1 lacked IL-2R/Tac-inducing activity on ED cells despite their IL-2R/Tac induction on YT, indicating that ADF and IL-1 have their effect via different receptors.