Hydrogen sulfide inhibits human T-cell leukemia virus type-1 (HTLV-1) protein expression via regulation of ATG4B

Hydrogen sulfide (H₂S) is a redox gasotransmitter. It has been shown that H₂S has a key role in host antiviral defense by inhibiting interleukin production and S-sulfhydrating Keap1 lead to Nrf2/ARE pathway activation. However, it is yet unclear whether H₂S can play an antiviral role by regulating autophagy. In this study, we found that exogenous H₂S decreased the expression of human T-cell leukemia virus type-1 (HTLV-1) protein and HTLV-1 induced autophagosomes accumulation. Transmission electron microscope assays indicated that autophagosomes accumulation decreased after H₂S administration. HTLV-1-transformed T-cell lines had a high level of CSE (H₂S endogenous enzyme) which could be induced in Hela by HTLV-1 infection. Immunoblot demonstrated that overexpression of CSE inhibited HTLV-1 protein expression and autophagy. And we got the opposite after CSE knockdown. Meanwhile, H₂S could not restrain the autophagy when ATG4B had a mutant at its site of 89. In a word, these results suggested that H₂S modulated HTLV-1 protein expression via ATG4B. Therefore, our findings suggested a new mechanism by which H₂S defended against virus infection.     

Natural history of human T-lymphotropic virus type 1 (HTLV-1) infection

The natural history of human T-lymphotropic virus type-1 (HTLV-1) infection has been difficult to be clarified, because only a small proportion of HTLV-1 carriers develop adult T-cell leukemia(ATL) after a long incubation period. We have performed a long-term follow-up study of HTLV-1 carriers for 17 years. Based on the findings of this study and other studies, the natural history of HTLV-1 carriers is hypothesized as follows. The major routes of infection of this virus are from mother to child, between spouses, and through blood products. The target of HTLV-1 infection is CD4 positive peripheral blood mononuclear cells (PBMCs). The number of infected cells is supposed to be increased just after the infection, then decreased in a year. The number of infected cells does not change thereafter during more than 10 years. In 90% of newly infected people, this level is low or medium ranging from less than 0.05% to 5% of PBMCs infected; however, approximately 10% of newly infected people develop into carriers with many number of infected cells as more than 5% of PBMCs infected. Clonal expansion of infected cells is likely to be contributing to the maintenance of the HTLV-1 infection. Replication of certain clones among many infected cells may be accelerated by the expression of Tax protein and some of them develop to have a phenotype to avoid immune surveillance. Finally, some of these clones, which acquired the accumulation of genomic abnormality, develop the pre-leukemic state. The increased number of certain T-cells due to HTLV-1 infection may also cause imbalance of the immune system, resulting in immune dysfunction or inflammatory diseases like myelopathy and uveitis. Therefore, it seems to be important to find ways to prevent HTLV-1 associated diseases among the carriers especially those with many infected cells.     

Human T-lymphotropic virus type-1 (HTLV-1) in Israeli patients and their family relatives and its transmission to rats

We tested the possibility that lymphocytes, sera and saliva, obtained directly from healthy human T-lymphotropic virus type 1 (HTLV-1) carriers and patients with HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) of Iranian Mashhadi origin, as well as lymphocytes from patients with mycosis fungoides (MF) and their family relatives (MFR), may be infective. Peripheral blood mononuclear cells (PBMC), sera, PBMC cultured with phytohaemagglutinin A and phorbol myristate acetate, cell-free supernatant from these cultures, saliva cells and cell-free saliva were injected into adult WKA (n=107) and F344 (n=47) female rats. The appearance of anti-HTLV-1 antibodies in the rat sera was tested by particle agglutination assay and ELISA, and positive results were confirmed by western blot assay. Higher titers (1:1024) of anti-HTLV-1 antibodies were found in the F344 rats as compared to the WKA rats (1:256). The PA agglutination test was the most sensitive for the detection of HTLV-1 antibody. The HTLV-1 provirus was detected in both strains of rats infected with body fluids and cells from the Iranian Mashhadi Jews, in various organs (PBMC, spleen, thymus, salivary glands, spinal cord, kidney and brain) by nested PCR. However, the HTLV-1 provirus was not detected in 100% of the rats. The negative rats were only immunized and not infected. The spleen, thymus, spinal cord and salivary glands of the seropositive rats were found to be infectious and to transmit the HTLV-1 to healthy rats. F344 rats infected with PBMC cultures obtained from HTLV-1 antibody positive MF patients and their MFR who were only 20% positive showed anti-HTLV-1 antibodies, but only in 20% of rats without showing the HTLV-1 provirus; these rats were probably not infected but only immunized. This is one of the few studies on the transmission of HTLV-1 to rats by inoculation with human infectious fluids or cells from HTLV-1 infected healthy carriers (42%), HAM/TSP patients of Iranian Mashhadi origin (58%) as well as lymphocyte cultures obtained from HTLV-1 antibody positive MF and MFR of nonIranian origin.     

Human T cell leukemia virus type 2 (HTLV-2) Tax2 has a dominant activity over HTLV-1 Tax1 to immortalize human CD4+ T cells

While human T cell leukemia virus type 1 (HTLV-1) is the causative agent of adult T cell leukemia, a close relative, HTLV-2, is not associated with any leukemia. HTLV-1 and HTLV-2 encode the Tax1 and Tax2 proteins, respectively, which are essential for the immortalization of human T cells by the respective viruses, thereby causing persistent infection. In this study, we compared Tax1 and Tax2 with respect to their immortalization activity in human T cells. Lentivirus-mediated transduction of the tax2 gene into human peripheral blood mononuclear cells stimulated with phytohemagglutinin and interleukin-2 in 96-well plates induced outgrowing T cells in most wells, but the cells infected with the control viruses died within 3 weeks. Surprisingly, the number of outgrowing cells induced by Tax2 was much higher than that induced by Tax1, and the appearance of outgrowing cells by Tax2 was earlier than that induced by Tax1. Nevertheless, both Tax2 and Tax1 preferentially immortalized CD4⁺ T cells, but not CD8⁺ T cells. Our study showed that HTLV-2 Tax2 can immortalize human CD4⁺ T cells, and the activity is much higher than that of Tax1. The distinct T cell immortalization activities of Tax2 and Tax1 might therefore play a role in the different pathogeneses observed for these two viruses.     

Selective depletion of cyclin-dependent kinases is associated with Fas-mediated apoptosis in human leukemia T-cell lines

The Fas/Apo-1 molecule is a member of tumor necrosis factor/nerve growth factor (TNF/NGF) receptor family and is able to induce apoptosis in various type of malignant cells, including most of the human leukemia T-cells. We previously demonstrated that the Fas-resistant variants may exist in highly Fas-sensitive human leukemia T-cell lines. The surface expression of Fas antigen was unchanged in the variant cells, suggesting the requirement of the cytoplasmic mechanism to exert apoptosis. In the present study, we examined the changes in cytoplasmic proteins of the Fas-sensitive and Fas-resistant cells after stimulation with anti-Fas antibody, 2D 1. In Western blotting analysis, we found that the stimulation of Fas-sensitive cells with 2D 1, but not resistant variants, induced a repression of cyclin-dependent kinases (cdks), p34cdc2 and p33cdk2, along with apoptosis. There was no alteration in the expression of bcl-2, HSP70, HSP90, and cyclin proteins examined. This observation seemed specific to Fas-mediated apoptosis, because calcium ionophore A23187 or sodium azide failed to repress the expression of cdks. These results indicate that the specific depletion of cdks, most likely due to proteolysis, may play a role in Fas-mediated apoptosis.     

Human T-cell leukemia virus type-I oncoprotein Tax inhibits Fas-mediated apoptosis by inducing cellular FLIP through activation of NF-kappaB

Human T-cell leukemia virus type I (HTLV-I) is an etiologic agent of adult T-cell leukemia and induces autoimmune disease. Previous analyses of tax transgenic mice suggested that protection of peripheral T-cells from Fas-mediated apoptosis by virus-encoded oncoprotein Tax was relevant to the onset of HTLV-I-induced diseases. Here, we show the high level expression of cellular FLICE/caspase-8-inhibitory protein (c-FLIP) in Tax-expressing HTLV-I-infected T-cells. The silencing of c-FLIP expression by a lentivirus-based RNA interference system rendered Tax-positive HTLV-I-infected T-cells sensitive to Fas-mediated apoptosis. Exogenously expressed Tax by using a conditional Cre-loxP-mediated inducible system also inhibited Fas-mediated apoptosis by up-regulating c-FLIP expression in HTLV-I-negative T-cells. Tax mutant d3 which cannot activate CREB/ATF1, while another M22 mutant which cannot activate NF-kappaB did not, suppressed Fas-mediated apoptosis by inducing c-FLIP expression. Furthermore, expression of the dominant negative mutant of either NF-kappaB or IkappaBalpha canceled not only c-FLIP expression but also inhibitory activity against Fas-mediated apoptosis by Tax. Inactivation of NFAT, however, did not decrease the expression of c-FLIP in HTLV-I-infected T-cells. Taken together, Tax inhibits Fas-mediated apoptosis by up-regulating c-FLIP expression in HTLV-I-infected cells, and NF-kappaB activity plays an essential role in the up-regulation of c-FLIP.     

X-linked inhibitor of apoptosis (XIAP) confers human trophoblast cell resistance to Fas-mediated apoptosis

Apoptosis occurs in the placenta throughout gestation, with a greater frequency near term in comparison to the first trimester. The Fas/FasL system represents one of the main apoptotic pathways controlling placental apoptosis. Although first trimester trophoblast cells express both Fas and FasL, they are resistant to Fas-induced apoptosis. Therefore, trophoblast resistance to Fas-mediated apoptosis may be due to the inhibition of the pathway downstream of Fas stimulation. Expression levels of X-linked inhibitor of apoptosis (XIAP) were recently shown to decrease in third trimester placentas, correlating with an increase in placental apoptosis. As a potent caspase inhibitor, XIAP prevents the activation of caspase-9 through its BIR3 domain and caspase-3 activation via the linker-BIR2 domain. In the present study, high levels of the active form of XIAP were detected in first trimester trophoblast cells, whereas term placental tissue samples predominantly expressed the inactive form of XIAP. Using a XIAP inhibitor, phenoxodiol, we demonstrate that XIAP inactivation sensitizes trophoblast cells to Fas stimulation, as evidenced by the anti-Fas mAb-induced decrease in trophoblast cell viability and increase in caspase-8, caspase-9 and caspase-3 activation. This suggests a functional role for XIAP in the regulation of the Fas apoptotic cascade in trophoblast cells during pregnancy.     

Prevalence of human T-cell lymphotropic virus type 1 (HTLV-1) and HTLV-2 infection among Spanish drug users measured by HTLV-1 assay and HTLV-1 and -2 assay. HTLV-1 and HTLV-2 Spanish Study Group.

The prevalence of human T-cell lymphotropic virus type 1 (HTLV-1) and HTLV-2 infection in 1992 and 1993 was determined by testing 2,152 specimens from injection drug users living in 11 geographic areas in Spain. Results obtained by an authentic HTLV-1 and -2 test were compared with those obtained by an HTLV-1 assay. HTLV infection was identified in 7 of 11 regions, with an overall prevalence of 2.5% (range, 0.4 to 11.5%). Fourty-four (81%) of 54 subjects were infected with HTLV-2; the viral strains in the remaining 10 subjects could not be serologically typed. Underestimation of HTLV infection because of the low sensitivities of HTLV-1 enzyme immunoassays for HTLV-2 antibody was relatively low (< 20%). Therefore, previous epidemiologic findings generated with HTLV-1 enzyme immunoassays appear to be reasonably accurate. Our results suggest that the rate of HTLV infection may have been increasing recently among Spanish drug users.     

Translation efficiency of the human T-cell leukemia virus (HTLV-2) gag gene modulates the frequency of ribosomal frameshifting

The regulation of ribosomal frameshifting during translation of the polycistronic mRNA of human T-cell leukemia virus (HTLV) was studied in a cell-free system. Translation inhibitors such as cycloheximide and puromycin antibiotics were much more effective in blocking the synthesis of the frameshift polypeptide Gag-Pro than the synthesis of the Gag product. The preferential inhibition of the frameshift polypeptide Gag-Pro by the two antibiotics was not a reflection of the different sizes of the two gene products, but rather a consequence of the effect of the inhibitors on ribosomal translation efficiencies. To further analyze the effect of translation efficiencies on ribosomal frameshifting, we compared the translation of 5'-capped RNA to noncapped RNA. The translation of 5'-capped RNA was higher, as expected. Consequently, ribosomal frameshifting producing the Gag-Pro polypeptide was enhanced when compared to the translation of noncapped RNA. Taken together these results indicate that efficiencies of translation, in conjunction with the cis regulatory genetic elements at the frameshift sites, determine the ratio of the polypeptides Gag, Gag-Pro, and Gag-Pro-Pol produced in the HTLV-infected cell. Thus, physiological changes which affect the cellular translation machinery may alter the optimal ratio of these three polyprotein products needed for virus maturation.     

Prevalence of antibody to human T-lymphotropic virus type-1 (HLTV-1) in Australian aborigines, and detection in Indonesian sera

The first finding of antibody to human T-lymphotropic virus type 1 in Australia, specifically in Australian Aborigines, is reported. The overall results suggest that this is a new area to be added to the known endemic areas for this virus. Antibody prevalence in each of two widely separated areas was found to be approximately 16% in 1977, and in one of these areas this had increased to approximately 34% in 1984/86. In this area no antibody to this virus was detected in children under 4 years of age.     

Enhanced specificity of truncated transmembrane protein for serologic confirmation of human T-cell lymphotropic virus type 1 (HTLV-1) and HTLV-2 infections by western blot (immunoblot) assay containing recombinant envelope glycoproteins.

Immunoassays based on the highly immunogenic transmembrane protein of human T-cell lymphotropic virus type 1 (HTLV-1) (protein 21c) are capable of detecting antibodies in all individuals infected with HTLV-1 and HTLV-2. However, because of antigenic mimicry with other cellular and viral proteins, such assays also have a large proportion of false-positive reactions. We have recently identified an immunodominant epitope, designated GD21-I located within amino acids 361 to 404 of the transmembrane protein, that appears to eliminate such false positivity. This recombinant GD21-I protein was used in conjunction with additional recombinant HTLV type-specific proteins and a whole virus lysate to develop a modified Western blot (immunoblot) assay (HTLV WB 2.4). The sensitivity and specificity of this assay were evaluated with 352 specimens whose infection status was determined by PCR assay for the presence or absence of HTLV-1/2 proviral sequences. All HTLV-1-positive (n = 102) and HTLV-2-positive (n = 107) specimens reacted with GD21-1 in the HTLV WB 2.4 assay, yielding a test sensitivity of 100%. Furthermore, all specimens derived from individuals infected with different viral subtypes of HTLV-1 (Cosmopolitan, Japanese, and Melanesian) and HTLV-2 (IIa0, a3, a4, IIb1, b4, and b5) reacted with GD21-I in the HTLV WB 2.4 assay. More importantly, HTLV WB 2.4 analysis of 81 PCR-negative specimens, all of which reacted to recombinant protein 21e in the presence or absence of p24 and p19 reactivity in the standard WB assay, showed that only two specimens retained reactivity to GD21-I, yielding an improved test specificity for the transmembrane protein of 97.5%. None of 41 specimens with gag reactivity only or 21 HTLV-negative specimens demonstrated reactivity to GD21-I. In an analysis of additional specimens (n = 169) from different geographic areas for which PCR results were not available, a substantial increase in the specificity of GD21-I detection was demonstrated, with no effect on the sensitivity of GD21-I detection among specimens from seropositive donors. Thus, the highly sensitive, GD21-I-based HTLV WB 2.4 assay eliminates the majority of false-positive transmembrane results, thereby increasing the specificity for serologic confirmation of HTLV-1 and HTLV-2 infections.     

Molecular biology and pathogenesis of the human T-cell leukaemia/lymphotropic virus Type-1 (HTLV-1)

Retroviruses are associated with a variety of diseases, including immunological and neurological disorders, and various forms of cancer. In humans, the Human T-cell Leukaemia/Lymphotropic virus type 1 (HTLV-1), which belongs to the Oncovirus family, is the aetiological agent of two diverse diseases: Adult T-cell leukaemia/lymphoma (ATLL) (Poiesz et al. 1980; Hinuma et al. 1981; Yoshida et al. 1982), as well as the neurological disorder tropical spastic paraparesis/HTLV-1-associated myelopathy (TSP/HAM) (Gessain et al. 1985; Rodgers-Johnson et al. 1985; Osame et al. 1986). HTLV-1 is the only human retrovirus known to be the aetiological agent of cancer. A genetically related virus, HTLV-2, has been identified and isolated (Kalyanaraman et al. 1982). However, there has been no demonstration of a definitive aetiological role for HTLV-2 in human disease to date. Simian T-cell lymphotropic viruses types 1 and 2 (STLV-1 and -2) and bovine leukaemia virus (BLV) have also been classified in same group, Oncoviridae, based upon their similarities in genetic sequence and structure to HTLV-1 and -2 (Burny et al. 1988; Dekaban et al. 1995; Slattery et al. 1999). This article will focus on HTLV-1, reviewing its discovery, molecular biology, and its role in disease pathogenesis.     

High prevalence of human T-lymphotropic virus type 1 (HTLV-1) in immigrant male-to-female transsexual sex workers with HIV-1 infection

Human T-lymphotropic virus type 1 and 2 (HTLV-1 and HTLV-2) infections in Europe are limited to intravenous drug users and migrants coming from areas in which they are endemic. A survey was undertaken of HTLV-1 and HTLV-2 infections in 393 recent immigrants: 167 HIV-1 positive subjects (including 52 male-to-female transsexual sex workers) and 226 pregnant HIV-1 negative women. The prevalence of HTLV-1 was 3.6% in the HIV-1 positive group and 0.9% in the HIV-1 negative group. The highest HTLV-1 prevalence in both groups was found in persons from Latin America, particularly those born in Peru (up to 26% in the HIV-1 positive group). All of the HIV-1/HTLV-1 co-infected individuals were male-to-female transsexual sex workers in whom the overall prevalence of HTLV-1 infection was 11.5%. HTLV-2 was only found in the HIV-1 positive group (prevalence 1.2%); all of the infected subjects were transsexual sex workers from Brazil (overall prevalence 6.4%). Phylogenetic analysis showed that all of the HTLV-1 isolates were of the cosmopolitan type, clustering with other strains circulating in the patients' birthplaces; the HTLV-2 isolates were of subtype 2a, and clustered significantly with other Brazilian strains. These results suggest the independent origin of each infection in the patient's birthplace. The data raise concerns about the further spread of HTLV infections mainly through the sexual route.     

Radioimmunoassay and enzyme-linked immunoassay of antibodies to the core protein (P24) of human T-lymphotropic virus (HTLV III)

Human T-cell lymphotropic viruses designated HTLV III or LAV are considered to represent the causative agent(s) of the acquired immunodeficiency syndrome (AIDS). Individuals who have been infected with these viruses may generally be identified on the basis of a positive serological test for antibodies against the protein components of these viruses. Purified viruses or viral proteins have been utilized for developing such tests. Since AIDS may be transmitted by blood transfusion and by blood products, screening of donors for antibodies to HTLV III/LAV has become a necessity. Such screening may be facilitated by the application of assays based on the use of crude virus-infected tissue culture media avoiding elaborate, expensive and potentially hazardous virus purification steps. Serum specimens were mixed with an appropriate dilution of an HTLV III-infected tissue culture-derived fraction, obtained by precipitation with polyethylene glycol 6000 and treatment with Tween 80 and tri-n-butylphosphate (to disrupt virus particles), and incubated with polystyrene beads coated with antibodies to HTLV III/LAV (anti-HTLV III). Subsequently, washed beads were incubated with either 125I- or beta-lactamase-labeled anti-HTLV III. The radioactivity or enzymatic activity associated with the beads was proportionate to the quantity of HTLV III antigen originally added to the beads. The presence of anti-HTLV III in serum specimens resulted in decreased antigen binding and thus in decreased radioactivity or diminished beta-lactamase activity associated with the beads. The test was specific for antibodies to the approximately equal to 24 kDa core protein of HTLV III. The prevalence of these antibodies (given in parentheses) in distinct populations was as follows: random blood donors (0.33%); hemophiliacs (36.4%); random homosexual males (25.1%); homosexual males preselected on the basis of positive markers for infection with hepatitis B virus (50%); and those with persistent lymphadenopathy (70%).     

Immunocytochemical and ultrastructural characterization of human T-lymphotropic virus type I (HTLV-I)-producing rabbit lymphoid cell lines

Summary Fine structural and immunocytochemical characterization of rabbit lymphoid cell lines transformed by human T-lymphotropic virus type I (HTLV-I) was carried out. All nine cell lines tested were reactive with anti-HTLV-I-positive human, monkey, and rabbit sera and monoclonal antibody to HTLV-Ip 19, but not with anti-HTLV-I-negative sera and monoclonal antibodies to human Ia and pan-T antigens. All cell lines were strongly positive for monoclonal antibodies to rabbit Ia and pan-T antigens. Ultrastructurally, each cell line contained C-type virus particles in varying numbers in the extracellular space. These particles showed replication patterns similar to those in HTLV-I or simian T-lymphotropic virus type I (STLV-I)-producing human or monkey cells. In addition, anti-HTLV-I-positive rabbit serum gave positive immunoreactivity to HTLV-I or STLV-I by indirect immunoferritin method.These results indicate that the ultramorphology and replication patterns of HTLV-I in rabbit cell lines are indistinguishable from those of HTLV-I in human and monkey cell lines, HTLV-I in rabbit cells shares the common surface antigenic determinants with HTLV-I or STLV-I in human or monkey cells, and that these cells are definitely rabbit T cells bearing their own Ia antigens.     

Inhibition by human T-lymphotropic virus (HTLV-I) of T-lymphocyte mitogenesis: failure of exogenous T-cell growth factor to restore responsiveness to lectin.

Various retroviruses, including human T-cell lymphotropic virus (HTLV-I) and avian sarcoma virus (ASV), can prevent coincubated human peripheral lymphocytes from responding efficiently to phytohaemagglutinin. Addition of high concentrations of T-cell growth factor (TCGF) activity usually overcomes this inhibition. However, such restoration of responsiveness does not occur in the case of HTLV-coincubated cells.     

Resistance to Fas-mediated apoptosis is restored by cycloheximide through the downregulation of cellular FLIPL in NK/T-cell lymphoma

Extranodal NK/T-cell lymphoma (NKTL), nasal type, is a highly aggressive neoplasm and is strongly associated with Epstein-Barr virus (EBV). In this study, we demonstrate that EBV-positive NKTL cell lines, namely, Hank-1, NK-YS, and NK-L, are resistant to Fas-mediated apoptosis induced by anti-Fas antibodies despite high levels of Fas surface expression and no mutation in the Fas gene. Fas stimulation of Hank-1 and NK-YS cells showed little processing of caspase 8, caspase 3, or bid, although the proximal signaling molecules of the death-inducing signaling complex, namely, Fas, Fas-associated protein with a death domain, caspase 8, and bid were present in these cells. Consistent with previous reports on the hypermethylation of death associated protein (DAP) kinase in NKTLs, the promoter of DAP kinase was methylated and its mRNA not detected in Hank-1 cells. However, the restoration of DAP kinase expression by 5-aza-2'-deoxycytidine did not sensitize Hank-1 to Fas-mediated apoptosis, indicating that DAP kinase deficiency does not contribute to resistance to Fas-mediated apoptosis. Since etoposide-induced apoptosis involved caspase 3 activation in Hank-1 and NK-YS cells, the caspase 3-dependent apoptotic machinery appears to be intact. Interestingly, cotreatment of Hank-1 with cycloheximide, a protein synthesis inhibitor, markedly sensitized cells to Fas-mediated apoptosis along with caspase 8 activation and c-FLIP(L) (cellular FLICE inhibitory protein long form) downregulation. Moreover, immunohistochemistry on paraffin-embedded tissue revealed c-FLIP expression in 39% (14 of 36) of NKTL patients. Taken together, these findings indicate that c-FLIP(L)-mediated resistance to Fas contributes to the development and progression of NKTLs. This study also suggests that agents capable of downregulating c-FLIP(L) could be used to treat NKTL.     

Elevated levels of beta-chemokines in bronchoalveolar lavage fluid (BALF) of individuals infected with human T lymphotropic virus type-1 (HTLV-1)

Pulmonary complications are known to develop in HTLV-1 carriers, including T lymphocytic alveolitis, and increased IL-2 receptor alpha (CD25)-bearing T cells have been found in BALF. Several chemokines may contribute to accumulation of T lymphocytes in the lungs of HTLV-1 carriers. Here, we compared the distribution of T lymphocyte subsets and beta-chemokines, such as macrophage inflammatory peptide-1alpha (MIP-1alpha), regulated on activation normal T expressed and secreted (RANTES), and macrophage chemoattractant protein-1 (MCP-1), in BALF and peripheral blood between HTLV-1 carriers and non-infected healthy normal subjects. Flow cytometric analysis with MoAbs to cell surface antigens was used to identify T lymphocyte subsets in BALF samples from HTLV-1 carriers (n = 13) and non-infected healthy controls (n = 10). The levels of different beta-chemokines were estimated by ELISA. High percentages of CD3+ cells, CD3 expressing HLA-DR antigen and CD3+CD25+ cells were detected in BALF of HTLV-1 carriers compared with non-infected controls. The concentration of MIP-1alpha in BALF of patients was significantly higher than in non-infected healthy controls and correlated well with the percentage of CD3+CD25+ cells. The level of RANTES in BALF was also significantly high in HTLV-1 carriers, but did not correlate with the percentage of CD3+CD25+ cells. On the other hand, the level of MCP-1 in BALF of HTLV-1 carriers was not different from that of controls. Our results suggest a possible interaction between activated T cells bearing CD25 and beta-chemokines, especially MIP-1alpha, which may contribute to the pulmonary involvement in HTLV-1 carriers.