C-C chemokine profile of cord blood mononuclear cells: selective defect in RANTES production

Three C-C chemokines inhibit human immunodeficiency virus (HIV) entry into macrophages: macrophage inflammatory protein-1alpha (MIP-1alpha), MIP-1beta, and regulated-upon activation, normal T-cell expressed and secreted (RANTES). We studied the ability of placental cord blood mononuclear cells (CBMC) to secrete these C-C chemokines in comparison to adult blood mononuclear cells (ABMC). CBMC had diminished ability to secrete RANTES, as determined by enzyme-linked immunosorbent assay. Secretion of MIP-1alpha and MIP-1beta were similar in CBMC and ABMC. Whereas MIP-1alpha and MIP-1beta secretion were comparable in monocytes and lymphocytes, RANTES was secreted primarily by lymphocytes. Flow cytometric analysis of RANTES expression showed diminished intracellular RANTES expression in cord blood lymphocytes (CBL) compared to adult (peripheral) blood lymphocytes (ABL). A subset analysis of RANTES-producing CBL and ABL demonstrated that RANTES was produced predominantly by CD8+/CD45RO+ cells. CBL had a reduced proportion of CD8+/CD45RO+ cells compared with ABL, which may account for the diminished RANTES secretion by CBMC. These results may be relevant to the pathogenesis of perinatal HIV infection. (Blood. 2000;95:715-718)     

Higher macrophage inflammatory protein (MIP)-1alpha and MIP-1beta levels from CD8+ T cells are associated with asymptomatic HIV-1 infection

To test the hypothesis that beta-chemokine levels may be relevant to the control of HIV in vivo, we compared RANTES, MIP-1alpha, and MIP-1beta production from purified CD8(+) T cells from 81 HIV-infected subjects and from 28 uninfected donors. Asymptomatic HIV(+) subjects produced significantly higher levels of MIP-1alpha and MIP-1beta, but not RANTES, than uninfected donors or patients that progressed to AIDS. In contrast, beta chemokines in plasma were either nondetectable or showed no correlation with clinical status. The high beta-chemokine-mediated anti-HIV activity was against the macrophage tropic isolate HIV-1(BAL), with no demonstrable effect on the replication of the T-cell tropic HIV-1(IIIB). These findings suggest that constitutive beta-chemokine production may play an important role in the outcome of HIV-1 infection.     

Correlation between plasma levels of cytokines and HIV-1 RNA copy number in HIV-infected patients

Summary The plasma levels of HIV-1 RNA, tumor necrosis factor alpha (TNF-α), soluble receptors type II of TNF-α (sTNF-α RII), soluble receptors of interleukin-4 (sR IL-4), interleukin-6 (IL-6), soluble receptors of interleukin-6 (sR IL-6), granulocyte macrophage colony stimulating factor (GM-CSF), soluble receptors of GM-CSF (sR GM-CSF), RANTES, MIP-1α and MIP-1β were measured in 80 HIV-infected patients. All patients had not been treated previously with antiretroviral drugs and did not present a recent history of opportunistic infection. A statistically significant correlation was found between HIV-1 RNA and TNF-α (p=0.005) or sTNF-α RII levels (p<0.001). RANTES and MIP-1α levels did not correlate with HIV-1 RNA. MIP-1β levels were correlated with plasma RNA titers in patients with CD4⁺ T cells <200 × 10⁶/l (p=0.03). MIP-1α and sR IL-4 levels were significantly different according to the CD4+ T cell range (p=0.003 and p=0.0002, respectively). GM-CSF and sR GM-CSF were undetectable in each case. These data confirm that HIV-1 replication in the plasma is correlated with TNF-α levels, but do not show a clear correlation with levels of the chemokines studied.     

CD8+ T-cell-derived soluble factor(s), but not β-chemokines RANTES, MIP-1α, and MIP-1β, suppress HIV-1 replication in monocyte/macrophages

It has been demonstrated that CD8⁺ T cells produce a soluble factor(s) that suppresses human immunodeficiency virus (HIV) replication in CD4⁺ T cells. The role of soluble factors in the suppression of HIV replication in monocyte/macrophages (M/M) has not been fully delineated. To investigate whether a CD8⁺ T-cell-derived soluble factor(s) can also suppress HIV infection in the M/M system, primary macrophages were infected with the macrophage tropic HIV-1 strain Ba-L. CD8⁺ T-cell-depleted peripheral blood mononuclear cells were also infected with HIV-1 IIIB or Ba-L. HIV expression from the chronically infected macrophage cell line U1 was also determined in the presence of CD8⁺ T-cell supernatants or β-chemokines. We demonstrate that: (i) CD8⁺ T-cell supernatants did, but β-chemokines did not, suppress HIV replication in the M/M system; (ii) antibodies to regulated on activation normal T-cell expressed and Secreted (RANTES), macrophage inflammatory protein 1α (MIP-1α) and MIP-1β did not, whereas antibodies to interleukin 10, interleukin 13, interferon α, or interferon γ modestly reduced anti-HIV activity of the CD8⁺ T-cell supernatants; and (iii) the CD8⁺ T-cell supernatants did, but β-chemokines did not, suppress HIV-1 IIIB replication in peripheral blood mononuclear cells as well as HIV expression in U1 cells. These results suggest that HIV-suppressor activity of CD8⁺ T cells is a multifactorial phenomenon, and that RANTES, MIP-1α, and MIP-1β do not account for the entire scope of CD8⁺ T-cell-derived HIV-suppressor factors.     

CC and CXC chemokines in breastmilk are associated with mother-to-child HIV-1 transmission

INTRODUCTION: CC and CXC chemokines may play a role in mother-to-child HIV-1 transmission by blocking HIV-1 binding to chemokine receptors and impeding viral entry into cells. METHODS: To define correlates of breastmilk chemokines and associations with infant HIV-1 acquisition, chemokines in breastmilk and infant HIV-1 infection risk were assessed in an observational, longitudinal cohort study. We measured MIP-1alpha, MIP-1beta, RANTES, and SDF-1 in month 1 breastmilk specimens from HIV-1-infected women in Nairobi and HIV-1 viral load was calculated in maternal plasma and breastmilk at delivery and 1 month postpartum. Infant infection status was determined at birth and months 1, 3, 6, 9, and 12. RESULTS: Among 281 breastfeeding women, 60 (21%) of their infants acquired HIV-1 during follow-up, 39 (65%) of whom became infected intrapartum or after birth. MIP-1alpha, MIP-1beta, RANTES, and SDF-1 were all positively correlated with breastmilk HIV-1 RNA (P<0.0005). Women with clinical mastitis had 50% higher MIP-1alpha and MIP-1beta levels (P<0.001 and P=0.006, respectively) and women with subclinical mastitis (breastmilk Na(+)/K(+)>1) had approximately 70% higher MIP-1alpha, MIP-1beta and RANTES (P<0.002 for all) compared to women without mastitis. Independent of breastmilk HIV-1, increased MIP-1beta and SDF-1 were associated with reduced risk of infant HIV-1 (RR=0.4; 95% CI 0.2-0.9; P=0.03 and RR=0.5; 95% CI=0.3-0.9; P=0.02, respectively) and increased RANTES was associated with higher transmission risk (RR=2.3; 95% CI 1.1- 5.3; P=0.04). CONCLUSIONS: These observations suggest a complex interplay between virus levels, breastmilk chemokines, and mother-to-child HIV-1 transmission and may provide insight into developing novel strategies to reduce infection across mucosal surfaces.     

HIV-1 infection through the CCR5 receptor is blocked by receptor dimerization

The identification of the chemokine receptors as receptors for HIV-1 has boosted interest in these molecules, raising expectations for the development of new strategies to prevent HIV-1 infection. The discovery that chemokines block HIV-1 replication has focused attention on identifying their mechanism of action. Previous studies concluded that this inhibitory effect may be mediated by steric hindrance or by receptor down-regulation. We have identified a CCR5 receptor-specific mAb that neither competes with the chemokine for binding nor triggers signaling, as measured by Ca(2+) influx or chemotaxis. The antibody neither triggers receptor down-regulation nor interferes with the R5 JRFL viral strain gp120 binding to CCR5, but blocks HIV-1 replication in both in vitro assays using peripheral blood mononuclear cells as HIV-1 targets, as well as in vivo using human peripheral blood mononuclear cell-reconstituted SCID (severe combined immunodeficient) mice. Our evidence shows that the anti-CCR5 mAb efficiently prevents HIV-1 infection by inducing receptor dimerization. Chemokine receptor dimerization also is induced by chemokines and is required for their anti-HIV-1 activity. In addition to providing a molecular mechanism through which chemokines block HIV-1 infection, these results illustrate the prospects for developing new tools that possess HIV-1 suppressor activity, but lack the undesired inflammatory side effects of the chemokines.     

CCR5-binding chemokines modulate CXCL12 (SDF-1)-induced responses of progenitor B cells in human bone marrow through heterologous desensitization of the CXCR4 chemokine receptor

Although the SDF-1 (CXCL12)/CXCR4 axis is important for B-cell development, it is not yet clear to what extent CC chemokines might influence B lymphopoiesis. In the current study, we characterized CC chemokine receptor 5 (CCR5) expression and function of primary progenitor B-cell populations in human bone marrow. CCR5 was expressed on all bone marrow B cells at levels between 150 and 200 molecules per cell. Stimulation of bone marrow B cells with the CCR5-binding chemokine macrophage inflammatory protein 1beta (MIP-1beta; CCL4) did not cause chemotaxis, but CCL4 was able to trigger potent calcium mobilization responses and activation of the mitogen-activated protein kinase (MAPK) pathway in developing B cells. We also determined that CCR5-binding chemokines MIP-1alpha (CCL3), CCL4, and RANTES (CCL5), specifically by signaling through CCR5, could affect all progenitor B-cell populations through a novel mechanism involving heterologous desensitization of CXCR4. This cross-desensitization of CXCR4 was manifested by the inhibition of CXCL12-induced calcium mobilization, MAPK activation, and chemotaxis. These findings indicate that CCR5 can indeed mediate biologic responses of bone marrow B cells, even though these cell populations express low levels of CCR5 on their cell surface. Thus, by modulation of CXCR4 function, signaling through CCR5 may influence B lymphopoiesis by affecting the migration and maturation of B-cell progenitors in the bone marrow microenvironment.     

Highly active antiretroviral therapy normalizes the potential for MIP-1alpha production in HIV infection

DESIGN: The CC chemokines RANTES, MIP-1alpha and MIP-1beta are ligands for CCR5, which has been identified as the principal co-receptor for macrophage tropic strains of HIV-1. This study investigated whether the inducible levels of RANTES, MIP-1alpha and MIP-1beta produced by cultured whole blood samples related to different rates of progression of HIV infection and to the introduction of Nelfinavir-based highly active anti-retroviral therapy (HAART). METHODS: Study subjects were HIV-positive and categorized as "slow progressors" (n= 8) or as "fast progressors" (n= 7); the latter group were treated with HAART. MIP-1alpha, MIP-1beta and RANTES production was determined using commercial ELISA kits. RESULTS: The inducible production of MIP-1alpha by whole blood cells in culture was significantly depressed in patients starting therapy compared with "slow progressors" and "normal donors". The levels of MIP-1alpha significantly increased with therapy at 12 weeks compared with pre-HAART levels (P= O.05) and became comparable to that of "normals" and "slow progressors". Differences in the inducible levels of MIP-1beta and RANTES for the separate subject groups were not significant. CONCLUSIONS: The increase in inducible MIP-1alpha production following HAART might suggest a role for the chemokines in HIV disease, either for monitoring the outcome of therapy of HIV disease, or as a direct therapeutic intervention.     

Inhibition of HIV-1 replication by GB virus C infection through increases in RANTES, MIP-1alpha, MIP-1beta, and SDF-1

Background People coinfected with HIV and GB virus C (GBV-C) have lower mortality than HIV-positive individuals without GBV-C infection. HIV uses either of the chemokine receptors CCR5 and CXCR4 for entry into CD4-positive cells. Longer survival in HIV-positive individuals is associated with high serum concentrations of ligands for CCR5 (RANTES [regulated on activation, normal T-cell expressed and secreted] and macrophage inflammatory proteins [MIP] 1alpha and 1beta) and CXCR4 (stromal-derived factor [SDF-1]), and with decreased expression of CCR5 on lymphocytes. Methods Peripheral-blood mononuclear cells were coinfected with GBV-C and HIV, and HIV replication was monitored by measuring infectivity and HIV p24 antigen production. Chemokine secretion was measured by ELISA, chemokine-receptor expression by flow cytometry, and cellular chemokine mRNA expression by differential hybridisation. Findings GBV-C infection of peripheral-blood mononuclear cells resulted in decreased replication of both clinical and laboratory HIV strains that use either CCR5 or CXCR4 as their coreceptor. Inhibition was related to the dose and timing of the GBV-C infection. Expression of mRNA for RANTES, MIP-1alpha, MIP-1beta, and SDF-1 and secretion of the chemokines into culture supernatants were higher in GBV-C-infected cells than in mock-infected cells. The inhibitory effect of GBV-C on HIV replication was blocked by incubation with neutralising antibodies against the relevant chemokines, and surface expression of CCR5 was significantly lower in GBV-C-infected cells than in mock-infected cells. Interpretation GBV-C induces HIV-inhibitory chemokines and reduces expression of the HIV coreceptor CCR5 in vitro. This study provides insight into the epidemiological association between GBV-C infection and longer survival in HIV-infected individuals.     

Short communication: Influence of active tuberculosis on chemokine and chemokine receptor expression in HIV-infected persons

Tuberculosis (TB) is the major opportunistic infection of HIV-1-infected patients in developing countries. Concurrent infection with TB results in immune cells having enhanced susceptibility to HIV-1 infection, which facilitates entry and replication of the virus. Cumulative data from earlier studies indicate that TB provides a milieu of continuous cellular activation and irregularities in cytokine and chemokine circuits that favor viral replication and disease progression. To better understand the interaction of the host with HIV-1 during active tuberculosis, we investigated in vivo expression of the HIV-1 coreceptors, CCR5 and CXCR4, and circulating levels of the inhibitory beta-chemokines, macrophage inflammatory protein-1-alpha (MIP-1alpha), macrophage inflammatory protein-1-beta (MIP-1beta), and regulated upon activation T cell expressed and secreted (RANTES), in HIV-positive individuals with and without active pulmonary tuberculosis. We found a significant decrease from normal in the fraction of CD4+ T cells expressing CCR5 and CXCR4 in individuals infected with HIV. However, CCR5 and CXCR4 expression did not differ significantly between HIV patients with and without tuberculosis. Higher amounts of MIP-1alpha, MIP-1beta, and RANTES were detected in plasma of HIV-1-positive individuals, particularly those with dual infection, although the increase was not found to be statistically significant.     

Phosphoantigen-reactive Vgamma9Vdelta2 T lymphocytes suppress in vitro human immunodeficiency virus type 1 replication by cell-released antiviral factors including CC chemokines.

Vgamma9Vdelta2 T lymphocytes are broadly reactive against various intracellular pathogens and display both lytic and proliferative responses to human immunodeficiency virus (HIV)-infected cells. HIV infection of peripheral blood mononuclear cell cultures led to absolute increases in Vgamma9Vdelta2 T cells accompanied by decreased p24 levels. Strong gammadelta T cell activation with nonpeptidic mycobacterial phosphoantigens (TUBAg1 extract or synthetic isopentenyl pyrophosphate) resulted in potent inhibition of HIV replication through soluble released factors. Subsequent analyses showed that phosphoantigen-activated gammadelta T cells produced substantial amounts of beta-chemokines (macrophage inflammatory protein [MIP]-1alpha, MIP-1beta, and regulated-on-activation, normal T-cell-expressed and -secreted beta-chemokine [RANTES]), which represent the natural ligand for the CCR5 HIV coreceptor. Accordingly, anti-beta-chemokine antibodies neutralized the inhibition of monocytotropic HIV strains by gammadelta T cell-released factors. Moreover, a T-tropic HIV strain using the CXCR4 coreceptor for virus entry was potently inhibited. Together, these data reveal that phosphoantigen-activated gammadelta T cells are an important source of CC chemokines and may suppress HIV replication through cell-released antiviral factors.     

Induction of G1 cycle arrest in T lymphocytes results in increased extracellular levels of beta-chemokines: a strategy to inhibit R5 HIV-1

The beta-chemokines RANTES (regulated on activation, normal T cell expressed and secreted), macrophage inflammatory protein-1alpha (MIP-1alpha), and MIP-1beta are the natural ligands of the HIV-1 coreceptor CCR5 and compete with the virus for receptor binding. We show that secretion of the beta-chemokines by activated lymphocytes starts before cellular DNA synthesis is detected and demonstrate that transient prolongation of the G(1) phase of the cell cycle by treatment with cytostatic drugs results in increased levels of the three chemokines in culture supernatants. Supernatants collected from peripheral blood mononuclear cells exposed to hydroxyurea, which arrests the cell cycle in late G(1), contained high levels of beta-chemokines. These supernatants were able to inhibit HIV-1 replication when added to cultures of infected lymphocytes. The observed antiviral effect likely was due to the increased levels of beta-chemokines RANTES, MIP-1alpha, and MIP-1beta because (i) supernatants greatly inhibited the replication of HIV-1 BaL, whereas they affected HIV-1 IIIb replication only slightly; (ii) neutralizing antibodies against the chemokines abrogated the antiviral effect of the supernatants; and (iii) the hydroxyurea concentrations shown to up-regulate chemokine levels were not sufficient to inhibit virus replication by depletion of intracellular nucleotide pools. Although antiviral properties have been reported previously for the cytostatic agents shown here to up-regulate beta-chemokine levels, our results provide an additional mechanism by which these drugs may exert antiviral activity. In summary, increased extracellular levels of anti-HIV-1 beta-chemokines resulting from transient prolongation of the G(1) phase of the lymphocyte cell cycle by treatment with cytostatic drugs may help to control the replication of CCR5-using strains of HIV-1.     

Acquisition of HIV type 1 resistance by beta-chemokine-producing CD4+ T cells.

The CD4+ T cell is a major target cell type for human immunodeficiency virus type 1 (HIV-1) infection. In this study, we provide evidence that the susceptibility to HIV-1 infection is variable in individual CD4+ T cells. Five CD4+ T cell clones were isolated from an HIV-1-seronegative donor and were investigated for their susceptibility to HIV-1 infection. Four CD4+ T cell clones were resistant to infection by a macrophage-tropic (R5) HIV-1 isolate whereas one clone was fully permissive. The level of susceptibility to HIV-1 correlated inversely with beta-chemokine production, including RANTES (regulated on activation, normally T cell expressed and secreted), macrophage inflammatory protein 1alpha (MIP-1alpha), and MIP-1beta. Resistance to HIV-1 infection was abrogated by the combined use of neutralizing antibodies against these three beta-chemokines. Interestingly, a complete inhibition of HIV-1 infection was observed in peripheral blood mononuclear cells on infection induced by adding the culture supernatant or a small number of HIV-1-resistant cell clones. Our results suggest the presence of a clonal self-defense mechanism within the CD4+ T cell population in vivo that involves the secretion of beta-chemokines.     

Expression and function of CXC and CC chemokines in human malignant liver tumors: a role for human monokine induced by gamma-interferon in lymphocyte recruitment to hepatocellular carcinoma.

Chemotactic cytokines (chemokines) play an important role in the recruitment of lymphocytes to tissue by regulating cellular adhesion and transendothelial migration. This study examined the expression and function of CXC (human monokine induced by gamma-interferon [HuMig], interleukin-8 [IL-8], and interferon-inducible protein-10 [IP-10]) and CC (macrophage inflammatory protein-1alpha [MIP-1alpha], MIP-1beta, regulated upon activation normal T lymphocyte expressed and secreted (RANTES), and macrophage chemoattractant protein-1 [MCP-1]) chemokines and their respective receptors on lymphocytes infiltrating human liver tumors. Chemokine and chemokine receptor expression was assessed by immunohistochemistry, flow cytometry, in situ hybridization and ribonuclease (RNAse) protection assays and function by in vitro chemotaxis of tumor-derived lymphocytes to purified chemokines and to HepG2 tumor cell culture supernatants. Tumor-derived lymphocytes showed strong chemotactic responses to both CC and CXC chemokines in vitro and expressed high levels of CXCR3 (HuMig and IP-10 receptor) and CCR5 (RANTES, MIP-1alpha, and MIP-1beta receptor). Expansion of tumor-derived lymphocytes in recombinant IL-2 increased expression of CXCR3. The corresponding chemokines were detected on vascular endothelium (HuMig, IL-8, MIP-1alpha, and MIP-1beta) and sinusoidal endothelium (HuMig, MIP-1alpha, MIP-1beta) in hepatocellular carcinoma. In vitro, HepG2 cells secreted functional chemotactic factors for tumor-derived lymphocytes that could be inhibited using anti-CCR5 or anti-CXCR3 monoclonal antibodies (MoAbs). Thus, lymphocytes infiltrating human liver tumors express receptors for and respond to both CXC and CC chemokines. The relevant chemokine ligands are expressed in hepatocellular carcinoma (HCC), particularly HuMig, which was strongly expressed by tumor endothelium, suggesting that they play a role in lymphocyte recruitment to these tumors in vivo. The ability of HepG2 cells to secrete lymphocyte chemotactic factors in vitro suggests that the tumor contributes to lymphocyte recruitment in vivo.     

Aminooxypentane-RANTES, an inhibitor of R5 human immunodeficiency virus type 1, increases the interferon gamma to interleukin 10 ratio without impairing cellular proliferation.

Studies have demonstrated that the beta-chemokines RANTES, MIP-1alpha, and MIP-1beta suppress human immunodeficiency type 1 (HIV-1) replication in vitro. Infection with HIV-1 requires expression of CD4 antigen and the chemokine receptor CXCR4 (X4) or CCR5 (R5) on the surface of target cells. The engagement of these receptors with the viral surface proteins is essential for the membrane fusion process. This study investigated the anti-HIV-1 activity of a derivative of RANTES, the CCR5 antagonist aminooxypentane (AOP)-RANTES, on R5 HIV-1 isolates in peripheral blood mononuclear cells. In drug exposure experiments, AOP-RANTES efficiently inhibited viral replication of HIV-1 R5 strains, with a viral breakthrough observed after the withdrawal of the compound. The HIV-1-specific proliferative capacity was maintained under all conditions when compared with controls. An increase in IFN-gamma production accompanied by a parallel decrease in the generation of IL-10 was observed following the in vitro exposure of cells to AOP-RANTES in the presence of three of four HIV-1 R5 isolates. These experiments confirmed that the chemokine receptor antagonist AOP-RANTES was effective as an inhibitor of HIV-1 R5 strain infectivity in peripheral blood mononuclear cells. The capacity of this compound to maintain HIV-1-specific proliferative activity with a shift toward a type 1 cytokine profile makes this compound a unique molecule, one adopting an immunological pathway to limit HIV-1 infection.     

Chemokine receptor 5 and its ligands in the immune response to murine tuberculosis

SETTING: The ability of chemokines such as macrophage inflammatory protein (MIP)-1alpha, MIP-1beta, and regulated-upon-activation, normal T cell expressed and secreted (RANTES), to attract and activate T cells and monocytes, the building blocks of the granuloma, suggests that these chemokines may have a role in modulating immune responses to Mycobacterium tuberculosis infection. OBJECTIVE: We hypothesized that the chemokine receptor 5 (CCR5) ligands, MIP-1alpha, MIP-1beta and RANTES, are virulence correlates in M. tuberculosis infection and are indispensable to granuloma formation. DESIGN: The ability of virulent (H37Rv) and avirulent (H37Ra) strains of M. tuberculosis to induce chemokine production in vivo and in vitro was determined at protein and mRNA levels. We also compared bacterial burden, and granuloma numbers and size in H37Rv-infected CCR5-/- or wild-type C57BL/6 mice. RESULTS: In vivo, lung mRNA and protein measurements of MIP-1alpha, MIP-1beta and RANTES indicate significantly higher (p<0.05) values (days 14-28) in the H37Rv-infected than the H37Ra-infected mice. This is consistent with a higher infection burden of the virulent strain. However, in vitro alveolar macrophage stimulation by H37Rv or H37Ra yielded no significant differences in production of the three chemokines at all time points. Histological analysis of granulomas did not show any significant differences in granuloma numbers, size and M. tuberculosis growth in CCR5-/- compared to wild-type mice. CONCLUSIONS: The production of the CCR5 ligands, MIP-1alpha, MIP-1beta, and RANTES, does not clearly correlate with virulence of M. tuberculosis. These ligands and their receptors may not be indispensable to the development of granulomas in murine tuberculosis.     

HTLV-II down-regulates HIV-1 replication in IL-2-stimulated primary PBMC of coinfected individuals through expression of MIP-1alpha

The influence of human T-cell leukemia/lymphoma virus type II (HTLV-II) in individuals also infected with HIV-1 is poorly understood. To evaluate the reciprocal influence of HTLV-II and HIV-1 infection, primary peripheral blood mononuclear cell (PBMC) cultures from coinfected individuals were established in the presence of interleukin 2 (IL-2). In these cultures, the kinetics of HTLV-II replication always preceded those of HIV-1. Noteworthy, the kinetics of HIV-1 production were inversely correlated to the HTLV-II proviral load in vivo and its replication ex vivo. These observations suggested a potential interaction between the 2 retroviruses. In this regard, the levels of IL-2, IL-6, and tumor necrosis factor-alpha (TNF-alpha) were measured in the same coinfected PBMC cultures. Endogenous IL-2 was not produced, whereas IL-6 and TNF-alpha were secreted at levels compatible with their known ability to up-regulate HIV-1 expression. The HIV-suppressive CC-chemokines RANTES, macrophage inflammatory protein-1alpha (MIP-1alpha), and MIP-1beta were also determined in IL-2-stimulated PBMC cultures. Of interest, their kinetics and concentrations were inversely related to those of HIV-1 replication. Experiments were performed in which CD8(+) T cells or PBMCs from HTLV-II monoinfected individuals were cocultivated with CD4(+) T cells from HIV-1 monoinfected individuals separated by a semipermeable membrane in the presence or absence of antichemokine neutralizing antibodies. The results indicate that HTLV-II can interfere with the replicative potential of HIV-1 by up-regulating viral suppressive CC-chemokines and, in particular, MIP-1alpha. This study is the first report indicating that HTLV-II can influence HIV replication, at least in vitro, via up-regulation of HIV-suppressive chemokines. (Blood. 2000;95:2760-2769)     

HIV-1-suppressive factors are secreted by CD4+ T cells during primary immune responses

CD4+ T cells are required for immunity against many viral infections, including HIV-1 where a positive correlation has been observed between strong recall responses and low HIV-1 viral loads. Some HIV-1-specific CD4+ T cells are preferentially infected with HIV-1, whereas others escape infection by unknown mechanisms. One possibility is that some CD4+ T cells are protected from infection by the secretion of soluble HIV-suppressive factors, although it is not known whether these factors are produced during primary antigen-specific responses. Here, we show that soluble suppressive factors are produced against CXCR4 and CCR5 isolates of HIV-1 during the primary immune response of human CD4+ T cells. This activity requires antigenic stimulation of na?ve CD4+ T cells. One anti-CXCR4 factor is macrophage-derived chemokine (chemokine ligand 22, CCL22), and anti-CCR5 factors include macrophage inflammatory protein-1 alpha (CCL3), macrophage inflammatory protein-1 beta (CCL4), and RANTES (regulated upon activation of normal T cells expressed and secreted) (CCL5). Intracellular staining confirms that CD3+CD4+ T cells are the source of the prototype HIV-1-inhibiting chemokines CCL22 and CCL4. These results show that CD4+ T cells secrete an evolving HIV-1-suppressive activity during the primary immune response and that this activity is comprised primarily of CC chemokines. The data also suggest that production of such factors should be considered in the design of vaccines against HIV-1 and as a mechanism whereby the host can control infections with this virus.     

HIV type 2 primary isolates induce a lower degree of apoptosis "in vitro" compared with HIV type 1 primary isolates

To determine whether subtypes of HIV-1 and HIV-2 vary in their ability to induce T cell apoptosis in vitro, human peripheral blood mononuclear cells (PBMC) from healthy donors and CEM.NKR-CCR5 cells were infected with a variety of HIV-1 and HIV-2 isolates in vitro. Apoptotic cell levels and chemokine and cytokine production were analyzed. Significant variations in cytopathic effects following in vitro infection with primary isolates of HIV-1 or HIV-2 subtypes were observed in PBMCs. The percent of apoptotic cells from each individual ranged from 2 to 78% after HIV-1 infection and from 0 to 28% after HIV-2 infection (p < 0.01). We did not observe significant differences in the degree of apoptosis induced among cells infected with different HIV-1 group M subtypes or group O virus, nor among cells infected with different HIV-2 isolates. However, HIV-2 induced significantly lower degree of apoptosis overall in PBMC and CEM.NKR-CC5 cells when compared with HIV-1 subtypes (p < 0.0001). No significant differences were observed in the production of chemokines, such as RANTES, MIP-1alpha, and MIP-1beta, and cytokines, such as TNF-alpha and TNF-beta when PBMC cultures were infected with different HIV-1 subtype viruses, or HIV-2 isolates. In conclusion, HIV-2 isolates induced significantly lower levels of T cell apoptosis in both PBMC and CEM.NKR-CCR5 cells than HIV-1 isolates. No differences in T cell apoptosis levels were seen between different subtypes of HIV-1 group M or group O isolates. This is consistent with the mild clinical course of infection with HIV-2 that has been reported relative to that observed with HIV-1.