Increase in plasma IL-10 levels and rapid loss of CD4+ T cells among HIV-infected individuals in south India

Thymic Exhaustion and Increased Immune Activation Are the Main Mechanisms Involved in Impaired Immunological Recovery of HIV-Positive Patients under ART

Decades of studies in antiretroviral therapy (ART) have passed, and the mechanisms that determine impaired immunological recovery in HIV-positive patients receiving ART have not been completely elucidated yet. Thus, T-lymphocytes immunophenotyping and cytokines levels were analyzed in 44 ART-treated HIV-positive patients who had a prolonged undetectable plasma viral load. The patients were classified as immunological non-responders (INR = 13) and immunological responders (IR = 31), according to their CD4+ T cell levels. Evaluating pre-CD4+ levels, we observed a statistically significant trend between lower CD4+ T cell levels and INR status (Z = 3.486, p < 0.001), and during 18 months of ART, the CD4+ T cell levels maintained statistical differences between the INR and IR groups (WTS = 37.252, p < 0.001). Furthermore, the INRs were associated with an elevated age at ART start; a lower pre-treatment CD4+ T cell count and a percentage that remained low even after 18 months of ART; lower levels of recent thymic emigrant (RTE) CD4+ T cell (CD45RA + CD31+) and a naïve CD4+ T cell (CD45RA + CD62L+); higher levels of central memory CD4+ T cells (CD45RA-CD62L+); and higher immune activation by CD4+ expressing HLA-DR+ or both (HLA-DR+ and CD38+) when compared with IRs. Our study demonstrates that thymic exhaustion and increased immune activation are two mechanisms substantially implicated in the impaired immune recovery of ART-treated HIV patients.

Deficient IL-2 Produced by Activated CD56+ T Cells Contributes to Impaired NK Cell-Mediated ADCC Function in Chronic HIV-1 Infection

Background: Antibody-dependent cellular cytotoxicity (ADCC), which mainly mediated by natural killer (NK) cells, may play a critical role in human immunodeficiency virus type-1 (HIV-1) disease progression. However, the potential mechanisms that affecting NK-mediated ADCC response are still not well-elucidated. Methods: Antigen-antibody complex model of Ab-opsonized P815 cells was adopted to induce a typical non-specific ADCC response. The capacities of HIV-1 specific NK-ADCC were measured by using the combination model of gp120 protein and plasma of HIV-1 elite controllers. The levels of plasma cytokine were measured by ELISA. Anti-IL-2 blocking antibody was used to analyze the impact of activated CD56⁺ T cells on NK-ADCC response. Results: IL-2, IL-15, IFN-α, and IFN-β could effectively enhance the non-specific and HIV-1-specific NK-ADCC responses. Compared with healthy controls, HIV-1-infected patients showed decreased plasma IL-2 levels, while no differences of plasma IFN-α, IL-15, and IFN-β were presented. IL-2 production was detected from CD56⁺ T cells activated through antibody-dependent manner. The capability of NK-ADCC could be weakened by blocking IL-2 secretion from activated CD56⁺ T cells. Although no difference of frequencies of CD56⁺ T cells was found between HIV-1-infected patients and healthy controls, deficient IL-2 secretion from activated CD56⁺ T were found in chronic HIV-1 infection. Conclusions: The impaired ability of activated CD56⁺ T cells to secreting IL-2 might contribute to the attenuated NK cell-mediated ADCC function in HIV-1 infection.

The immunological response to syphilis differs by HIV status; a prospective observational cohort study

Background

It is not known if there is a difference in the immune response to syphilis between HIV-infected and uninfected individuals.

Methods

We prospectively recruited all patients with a new diagnosis of syphilis and tested their plasma for IFNα, IFNγ, IL-1β, IL-12p40, IL-12p70, IP-10, MCP-1, MIP-1α, MIP-1β, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10 and IL-17A at baseline pre-treatment and 6 months following therapy.

Results

A total of 79 HIV-infected [44 primary/secondary syphilis (PSS) and 35 latent syphilis (LS)] and 12 HIV-uninfected (10 PSS and 2 LS) cases of syphilis and 30 HIV-infected controls were included in the study. At the baseline visit, compared to the control group, concentrations of IL-10 were significantly elevated in the HIV-infected and uninfected groups. The level of IL-10 was significantly higher in the HIV-infected compared to the HIV-uninfected PSS group (25.3 pg/mL (IQR, 4.56–41.76) vs 2.73 pg/mL (IQR, 1.55–9.02), P = 0.0192). In the HIV-infected PSS group (but not the HIV-infected LS or HIV-uninfected PSS groups) the IP-10, MIP-1b, IL-6 and IL-8 were raised compared to the controls. IL-10 levels decreased but did not return to control baseline values by 6 months in HIV infected PSS and LS and HIV uninfected PSS.

Conclusion

PSS and LS in HIV-infected individuals is characterized by an increase in inflammatory and anti-inflammatory cytokines such as IL-10. The increase of IL-10 is greater in HIV-infected than uninfected individuals. Further work is required to ascertain if this is part of an immunological profile that correlates with adverse outcomes such as serofast syphilis and neurosyphilis, in HIV-infected individuals.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-017-2201-7) contains supplementary material, which is available to authorized users.

CD4+, CD8+, CD3+ cell counts and CD4+/CD8+ ratio among patients with mycobacterial diseases (leprosy, tuberculosis), HIV infections, and normal healthy adults: a comparative analysis of studies in different regions of India

In this study, we estimated the CD4+, CD8+, CD3+ cell counts and the CD4/CD8 ratio among normal healthy controls (adults and children), leprosy patients (without any complications and during reactional states), TB patients (with and without HIV), and HIV-positive patients (early infection and full-blown AIDS) and correlated the changes with disease progression. In our study, it was observed that among adults, CD4+ cell counts ranged from 518-1098, CD8+ from 312-952, whereas CD4/CD8 ratio from 0.75-2.30. Among children, both CD4+ and CD8+ cells were more and the CD4/CD8 ratio varied from 0.91-3.17. With regard to leprosy patients, we observed that CD4+ and CD8+ cell counts were lower among PB (pauci-bacillary) and MB (multi-bacillary) patients. CD4/CD8 ratio was 0.99 ± 0.28 among PB patients while the ratio was lower, 0.78 ± 0.20, among MB patients. CD4+ cell counts were raised during RR (reversal reactions) and ENL (erythema nodosum leprosum) among the PB and MB patients whereas the CD8+ cell counts were lower among PB and MB patients. CD4/CD8 ratio doubled during reactional episodes of RR and ENL. Among the HIV-negative tuberculosis (TB) patients, both the CD4+ and CD8+ cell counts were found to be less and the CD4/CD8 ratio varied between 0.53-1.75. Among the HIV-positive TB patients and HIV-positive patients, both the CD4+ and CD8+ cells were very less and ratio drops significantly. In the initial stages of infection, as CD4+ counts drop, an increase in the CD8+ cell counts was observed and the ratio declines. In full-blown cases, CD4+ cell counts were very low, 3-4 to 54 cells, CD8+ cells from 12-211 and the ratio drops too low. This study is the first of its kind in this region of the country and assumes importance since no other study has reported the values of CD4+ and CD8+ T-lymphocyte counts among patients with mycobacterial diseases (leprosy and TB), HIV infections along with normal healthy individuals of the region, and correlation with clinical presentations of patients.

Cytokine profiles at admission can be related to outcome in AIDS patients with cryptococcal meningitis

Cryptococcal meningitis (CM) remains as common life-threatening AIDS-defining illness mainly in resource-limited settings. Previous reports suggested that baseline cytokine profiles can be associated to fungal burden and clinical outcome. This study aimed to evaluate the baseline cytokine profiles in AIDS patients with CM and its relation with the outcome at weeks 2 and 10. Thirty AIDS patients with CM diagnosed by cerebrospinal fluid (CSF) Cryptococcus neoformans positive culture, India ink stain and cryptococcal antigen test were prospectively evaluated. As controls, 56 HIV-infected patients without CM and 48 non-HIV individuals were included. Baseline CSF and sera levels of IL-2, IL-4, IL-8, IL-10, IL-12p40, IL-17A, INF-γ and TNF-α were measured by ELISA. Of 30 CM patients, 24 (80%) were male, median age of 38.1. The baseline CSF high fungal burden and positive blood culture were associated with a positive CSF culture at week 2 (p = 0.043 and 0.029). Most CSF and sera cytokines presented higher levels in CM patients than control subjects (p < 0.05). CSF levels of IL-8, IL-12p40, IL-17A, TNF-α, INF-γ and sera TNF-α were significantly higher among survivors at weeks 2 and 10 (p < 0.05). Patients with increased intracranial pression exhibited CSF IL-10 high levels and poor outcome at week 10 (p = 0.032). Otherwise, baseline CSF log10 IFN-γ and IL-17A were negatively correlated with fungal burden (r = -0.47 and -0.50; p = 0.0175 and 0.0094, respectively). The mortality rate was 33% (10/30) at week 2 and 57% (17/30) at week 10. The severity of CM and the advanced immunodeficiency at admission were related to a poor outcome in these patients. Otherwise, the predominant Th1 cytokines profile among survivors confirms its pivotal role to infection control and would be a prognostic marker in cryptococcal meningitis.

Influence of cytokines on HIV-specific antibody-dependent cellular cytotoxicity activation profile of natural killer cells

There is growing interest in HIV-specific antibody-dependent cellular cytotoxicity (ADCC) as an effective immune response to prevent or control HIV infection. ADCC relies on innate immune effector cells, particularly NK cells, to mediate control of virus-infected cells. The activation of NK cells (i.e., expression of cytokines and/or degranulation) by ADCC antibodies in serum is likely subject to the influence of other factors that are also present. We observed that the HIV-specific ADCC antibodies, within serum samples from a panel of HIV-infected individuals induced divergent activation profiles of NK cells from the same donor. Some serum samples primarily induced NK cell cytokine expression (i.e., IFNγ), some primarily initiated NK cell expression of a degranulation marker (CD107a) and others initiated a similar magnitude of responses across both effector functions. We therefore evaluated a number of HIV-relevant soluble factors for their influence on the activation of NK cells by HIV-specific ADCC antibodies. Key findings were that the cytokines IL-15 and IL-10 consistently enhanced the ability of NK cells to respond to HIV-specific ADCC antibodies. Furthermore, IL-15 was demonstrated to potently activate “educated” KIR3DL1⁺ NK cells from individuals carrying its HLA-Bw4 ligand. The cytokine was also demonstrated to activate “uneducated” KIR3DL1⁺ NK cells from HLA-Bw6 homozygotes, but to a lesser extent. Our results show that cytokines influence the ability of NK cells to respond to ADCC antibodies in vitro. Manipulating the immunological environment to enhance the potency of NK cell-mediated HIV-specific ADCC effector functions could be a promising immunotherapy or vaccine strategy.

Enzymatic removal of mannose moieties can increase the immune response to HIV-1 gp120 in vivo

The Env glycoproteins gp120 and gp41 are used in humoral immunity-based vaccines against human immunodeficiency virus (HIV-1) infection. One among many obstacles to such a vaccine is the structural defenses of Env glycoproteins that limit their immunogenicity. For example, gp120 mannose residues can induce immunosuppressive responses in vitro, including IL-10 expression, via mannose C-type lectin receptors on antigen-presenting cells. Here, we have investigated whether mannose removal alters gp120 immunogenicity in mice. Administering demannosylated gp120 (D-gp120) in the T(H)2-skewing adjuvant Alum induced approximately 50-fold higher titers of anti-gp120 IgG, compared to unmodified gp120. While the IgG subclass profile was predominantly T(H)2-associated IgG1, Abs of the T(H)1-associated IgG2a and IgG3 subclasses were also detectable in D-gp120 recipients. Immunizing with D-gp120 also improved T-cell responses. Giving an IL-10 receptor blocking MAb together with unmodified gp120 in Alum increased the anti-gp120 IgG titer, implicating IL-10 as a possible mediator of auto-suppressive responses to gp120.

Altered cytokine profiles in patients with Chuvash polycythemia

Chuvash polycythemia results from a homozygous 598C>T mutation in exon 3 of the von Hippel-Lindau (VHL) gene. This disrupts the normoxia pathway for degrading hypoxia inducible factor (HIF)-1alpha and HIF-2alpha causing altered expression of HIF-1 and HIF-2 inducible genes. As hypoxia induces expression of pro-inflammatory cytokines, we hypothesized that there might be an elevation of Th1 cytokines in the setting of Chuvash polycythemia. We analyzed plasma concentrations of Th1 (interleukins-2 and 12, interferon-gamma, granulocyte-monocyte colony-stimulating factor, tumor necrosis factor-alpha) and Th2 cytokines (interleukins-4, 5, 10, and 13) using the Bio-Plex multiplex suspension array system in 34 VHL598C>T homozygotes and 32 VHL wild-type participants from Chuvashia. Concentrations of all the Th1 and Th2 cytokines measured were elevated in the VHL598C>T homozygotes compared with the control wild-type participants, but the ratios of Th1 to Th2 cytokines did not differ by genotype. In parallel, peripheral blood concentrations of CD4 positive T-helper cells and CD4/CD8 ratio were lower in the VHL598C>T homozygotes. In conclusion, the up-regulated hypoxic response in Chuvash polycythemia is associated with increased plasma products of both the Th1 and Th2 pathways, but the balance between the two pathways seems to be preserved.

Cocaine-mediated enhancement of virus replication in macrophages: implications for human immunodeficiency virus-associated dementia

Injection drug use has been recognized as a major risk factor for acquired immunodeficiency syndrome (AIDS) from the outset of the epidemic. Cocaine, one of the most widely abused drugs in the United States, can both impair the functions of macrophages and CD4(+) lymphocytes and also activate human immunodeficiency virus (HIV)-1 expression in these cells. Because the brain is the target organ for both cocaine and HIV, the objective of the present study was to explore the effects of cocaine on virus replication in macrophages, the target cells for the virus in the central nervous system (CNS). Cocaine markedly enhanced virus production in simian human immunodeficiency virus (SHIV)-infected monocyte-derived macrophages (MDMs) and in U1 cells, a chronically infected promonocytic cell line as monitored by enzyme-linked immunosorbent assay (ELISA) and immunocytochemistry. Cocaine treatment also resulted in the activation of nuclear factor (NF)-kappa B and transcriptional activation of the HIV-LTR (long terminal repeat) gag-GFP (green fluorescent protein). Analyses of chemokines in cocaine-treated macrophages by real-time reverse transcriptase-polymerase chain reaction (RT-PCR) and Luminex assays suggested increased expression of interleukin (IL)-10, a cytokine that is known to promote HIV replication in MDMs. In addition to enhancing IL-10 expression, cocaine also caused an up-regulation of the macrophage activation marker, human leukocyte antigen (HLA)-DR, in MDMs. The synergistic effect of cocaine on virus replication and its enhancement of host activation markers suggest that cocaine functions at multiple pathways to accelerate HIV-associated dementia (HAD).

Local immunity in Indian women with bacterial vaginosis

OBJECTIVES

To determine the immunoglobulin (Ig) and cytokine levels and degradation of Igs in the cervico-vaginal secretions (CVS) of non-pregnant Indian women of low socio economic status (LSES), with/without bacterial vaginosis (BV) and to assess the interactions among nutritional status, BV and local immunity.

METHODS

A descriptive study in non-pregnant women of LSES attending the gynecology out patient clinic at a local government hospital, Hyderabad, India. Two hundred non-pregnant women underwent clinical, anthropometrical and gynecological examination and were screened for BV. In a sub-sample of 80 with/without BV, levels of IL-10 and IL-12, IgA, IgM and IgG were determined in the CVS by ELISA and degradation of IgA and IgM by Western blotting. Statistical significance among the groups was tested using the non-parametric Mann-Whitney U-test.

RESULTS

Fifty seven percent of the women tested positive for BV. Women with BMI<16.0 had the highest BV positivity and the lowest IgA levels in CVS. Higher levels of IgA were observed in women with BMI>18.5. There was significant degradation of IgA and IgM in women with BV. IL-12 was undetectable while IL-10 was detected with higher means in CVS of women with BV.

CONCLUSIONS

Severe under-nutrition appears to be relevant to BV positivity and local immunity in these women. Greater degradation of IgA and IgM in BV suggests impaired local immunity.

HIV-specific CD8+ lymphocytes in semen are not associated with reduced HIV shedding

Sexual contact with HIV-infected semen is a major driving force behind the global HIV pandemic. Little is known regarding the immune correlates of virus shedding in this compartment, although HIV-1-specific CD8+ T cells are present in semen. We collected blood and semen from 27 chronically HIV-infected, therapy-naive men without common sexually transmitted infections or urethral inflammation and measured HIV-1 RNA viral load and cytokine/chemokine levels in both compartments. HIV-1 RNA levels were 10-fold higher in blood than semen, but discordantly high semen shedding was associated with higher semen levels of the proinflammatory cytokines IL-6, IL-8, IL-12, and IFN-gamma. Virus-specific CD8+ T cell epitopes were mapped in blood by IFN-gamma ELISPOT, using an overlapping HIV-1 clade B peptide matrix, and blood and semen CD8+ T cell responses were then assayed ex vivo using intracellular IFN-gamma staining. HIV-specific CD8+ responses were detected in 70% of semen samples, and their frequency was similar to or higher than blood. There was no correlation between the presence of virus-specific CD8+ T cells in semen and levels of HIV-1 RNA shedding. Among participants with detectable CD8+ IFN-gamma semen responses, their relative frequency was not associated with reduced HIV-1 RNA shedding, and their absolute number was correlated with higher levels of HIV-1 RNA semen shedding (r = 0.6; p = 0.03) and of several proinflammatory cytokines. Neither the presence nor the frequency of semen HIV-specific CD8+ T cell IFN-gamma responses in semen correlated with reduced levels of HIV RNA in semen.

Chronic immune activation associated with chronic helminthic and human immunodeficiency virus infections: role of hyporesponsiveness and anergy

Chronic immune activation is one of the hallmarks of human immunodeficiency virus (HIV) infection. It is present also, with very similar characteristics, in very large human populations infested with helminthic infections. We have tried to review the studies addressing the changes in the immune profiles and responses of hosts infected with either one of these two chronic infections. Not surprisingly, several of the immune derangements and impairments seen in HIV infection, and considered by many to be the "specific" effects of HIV, can be found in helminth-infected but HIV-noninfected individuals and can thus be accounted for by the chronic immune activation itself. A less appreciated element in chronic immune activation is the immune suppression and anergy which it may generate. Both HIV and helminth infections represent this aspect in a very wide and illustrative way. Different degrees of anergy and immune hyporesponsiveness are present in these infections and probably have far-reaching effects on the ability of the host to cope with these and other infections. Furthermore, they may have important practical implications, especially with regard to protective vaccinations against AIDS, for populations chronically infected with helminths and therefore widely anergic. The current knowledge of the mechanisms responsible for the generation of anergy by chronic immune activation is thoroughly reviewed.

HIV alters plasma and M. tuberculosis-induced cytokine production in patients with tuberculosis

To test the hypothesis that HIV infection brings about an alteration in the immune response to tuberculosis (TB), mycobacterial antigen-induced production and plasma levels of the inflammatory cytokine interferon-gamma (IFN-gamma) and its regulatory cytokines interleukin-12 (IL-12), IL-18, and IL-10 were determined in patients infected dually with HIV and TB and compared with individuals with either disease and with healthy controls. Peripheral blood mononuclear cells (PBMCs) of TB patients with HIV infection produced lesser amounts of IFN-gamma and IL-12 compared with TB patients without HIV infection after in vitro stimulation with mycobacterial antigens. There was no difference in antigen-induced IL-18 production in TB patients with or without HIV infection. The in vivo cytokine pattern did not correlate with that seen in vitro. Higher levels of IFN-gamma, IL-12, and IL-18 were detected in the plasma of TB patients infected with HIV compared with TB patients without HIV infection. The presence of significantly higher plasma levels of proinflammatory cytokines suggests a greater degree of immune activation in individuals with HIV and TB, particularly those with low CD4 counts. In vitro IL-10 production by HIV-positive TB patients was similar to that of the HIV-negative TB group and higher than in HIV-positive individuals without TB, but the plasma levels were similar. HIV infection downregulates the in vitro Th1 cytokine response to TB and simultaneously increases systemic levels of these cytokines.

Quantitation of simian cytokine and beta-chemokine mRNAs, using real-time reverse transcriptase-polymerase chain reaction: variations in expression during chronic primate lentivirus infection

Cytokines and beta-chemokines are important mediators of the immune system and are expressed in many infectious diseases. To study cytokine and beta-chemokine profiles during pathogenesis of lentiviral infection and progression to AIDS in rhesus macaques, we established new quantitative real-time reverse transcriptase-polymerase chain reaction (RT-PCR) assays based on TaqMan chemistry. Using synthetic RNA standards, we quantified mRNAs of IL-2, IL-4, IL-6, IL-10, IL-12 p40, interferon gamma (IFN-gamma), tumor necrosis factor alpha (TNF-alpha), RANTES, macrophage inflammatory protein 1 alpha (MIP-1 alpha), and MIP-1 beta in unstimulated peripheral blood mononuclear cells (PBMCs) and lymph nodes from macaques chronically infected with SIV or SHIV. Viremic monkeys with decreased CD4(+) T cell counts (<500 cells/microl) had significantly higher IL-10 mRNA expression than uninfected controls, which parallels the findings in HIV-1-infected humans. In addition, MIP-1 alpha, MIP-1 beta, and RANTES mRNA expression increased in viremic monkeys with decreased CD4(+) T cell counts; gene expression was inversely correlated with CD4(+) T cell counts, but not viral load. The newly established quantitative real-time RT-PCR assays will allow the determination of cytokine and beta-chemokine patterns in rhesus macaques in studies of microbial pathogenesis or vaccine development.

Contribution of immune activation to the pathogenesis and transmission of human immunodeficiency virus type 1 infection

The life cycle of human immunodeficiency virus type 1 (HIV-1) is intricately related to the activation state of the host cells supporting viral replication. Although cellular activation is essential to mount an effective host immune response to invading pathogens, paradoxically the marked systemic immune activation that accompanies HIV-1 infection in vivo may play an important role in sustaining phenomenal rates of HIV-1 replication in infected persons. Moreover, by inducing CD4+ cell loss by apoptosis, immune activation may further be central to the increased rate of CD4+ cell turnover and eventual development of CD4+ lymphocytopenia. In addition to HIV-1-induced immune activation, exogenous immune stimuli such as opportunistic infections may further impact the rate of HIV-1 replication systemically or at localized anatomical sites. Such stimuli may also lead to genotypic and phenotypic changes in the virus pool. Together, these various immunological effects on the biology of HIV-1 may potentially enhance disease progression in HIV-infected persons and may ultimately outweigh the beneficial aspects of antiviral immune responses. This may be particularly important for those living in developing countries, where there is little or no access to antiretroviral drugs and where frequent exposure to pathogenic organisms sustains a chronically heightened state of immune activation. Moreover, immune activation associated with sexually transmitted diseases, chorioamnionitis, and mastitis may have important local effects on HIV-1 replication that may increase the risk of sexual or mother-to-child transmission of HIV-1. The aim of this paper is to provide a broad review of the interrelationship between immune activation and the immunopathogenesis, transmission, progression, and treatment of HIV-1 infection in vivo.

Both Th1 and Th2 cytokines affect the ability of monoclonal antibodies to protect mice against Cryptococcus neoformans

Variable-region-identical mouse immunoglobulin G1 (IgG1), IgG2b, and IgG2a monoclonal antibodies to the capsular polysaccharide of Cryptococcus neoformans prolong the lives of mice infected with this fungus, while IgG3 is either not protective or enhances infection. CD4+ T cells are required for IgG1-mediated protection, and CD8+ T cells are required for IgG3-mediated enhancement. Gamma interferon is required for both effects. These findings revealed that T cells and cytokines play a role in the modulation of cryptococcal infection by antibodies and suggested that it was important to more fully define the cytokine requirements of each of the antibody isotypes. We therefore investigated the efficacy of passively administered variable-region-identical IgG1, IgG2a, IgG2b, and IgG3 monoclonal antibodies against intravenous infection with C. neoformans in mice genetically deficient in interleukin-12 (IL-12), IL-6, IL-4, or IL-10, as well as in the parental C57BL/6J strain. The relative inherent susceptibilities of these mouse strains to C. neoformans were as follows: IL-12(-/-) > IL-6(-/-) > C57BL/6J approximately IL-4(-/-) >> IL-10(-/-). This is consistent with the notion that a Th1 response is necessary for natural immunity against cryptococcal infection. However, none of the IgG isotypes prolonged survival in IL-12(-/-), IL-6(-/-), or IL-4(-/-) mice, and all isotypes significantly enhanced infection in IL-10(-/-) mice. These results indicate that passive antibody-mediated protection against C. neoformans requires both Th1- and Th2-associated cytokines and reveal the complexity of the mechanisms through which antibodies modulate infection with this organism.

Opposite effects of IL-10 on the ability of dendritic cells and macrophages to replicate primary CXCR4-dependent HIV-1 strains

We investigated the effect of IL-10 on replication of primary CXCR4-dependent (X4) HIV-1 strains by monocyte-derived dendritic cells (DCs) and macrophages (M Phis). M Phis efficiently replicated CXCR4-dependent HIV-1 (X4 HIV-1) strains NDK and VN44, whereas low levels of p24 were detected in supernatants of infected DCs. IL-10 significantly increased X4 HIV-1 replication by DCs but blocked viral production by M Phis as determined by p24 levels and semiquantitative nested PCR. IL-10 up-regulated CXCR4 mRNA and protein expression on DCs and M Phis, suggesting that IL-10 enhances virus entry in DCs but blocks an entry and/or postentry step in M Phis. The effect of IL-10 on the ability of DCs and M Phis to transmit virus to autologous CD4(+) T lymphocytes was investigated in coculture experiments. DCs exhibited a greater ability than did M Phis to transmit a vigorous infection to CD4(+) T cells despite their very low replication capacity. IL-10 had no effect on HIV-1 replication in DC:T cell cocultures but markedly decreased viral production in M Phi:T cell cocultures. These results demonstrate that IL-10 has opposite effects on the replication of primary X4 HIV-1 strains by DCs and M Phis. IL-10 increases X4-HIV-1 replication in DCs but does not alter their capacity to transmit virus to CD4(+) T lymphocytes. These findings suggest that increased levels of IL-10 observed in HIV-1-infected patients with disease progression may favor the replication of X4 HIV-1 strains in vivo.