Interference of cephalosporins with immune response: effects of cefonicid on human T-helper cells.

To determine the immunosuppressive effect(s) of cephalosporin cefonicid (CEFO) on human T-helper cells (Th), we exposed human peripheral blood mononuclear cells (PBMC) to various concentrations of CEFO during in vitro stimulation with a panel of T-lymphocyte stimulators that activate different Th/antigen presenting cell (APC) pathways. We evaluated the proliferation and IL-2 production induced by influenza virus (FLU), allogeneic lymphocytes (ALLO), xenogeneic mouse splenocytes (XENO) or phytohemagglutinin (PHA). The proliferative responses to FLU and XENO were much more depressed by CEFO than those to ALLO or PHA. After 7 days of culture with the highest dose of CEFO tested (200 mg/l) the stimulation index (stimulated/unstimulated culture) was near to 0 in FLU and XENO treated cultures, indicating that the response against these antigens was completely abrogated. The responses to ALLO and PHA were also impaired, but not abrogated (stimulation index greater than 1). Since FLU and XENO utilize the CD4+ Th/self-APC pathway our data suggested that this pathway was extremely sensitive to CEFO-induced inhibition both when the response requires memory Th cells (FLU) and virgin Th cells (XENO). The incubation with CEFO (200 mg/l) reduced the IL-2 production by XENO, FLU and ALLO to less than 20% of control cultures, while paradoxically increases to 120% the production by PHA.     

Dissociation of immunologic and virologic responses to highly active antiretroviral therapy

OBJECTIVE: Immunologic markers, levels of HIV DNA, and infectious HIV were compared in partial responders (PR) to HAART who had high plasma HIV RNA levels but stable or increasing levels of CD4+ peripheral blood mononuclear cells (PBMC), and patients with complete failure (CF) who had very low or decreasing levels of CD4+ PBMC and high plasma HIV RNA levels. DESIGN AND METHODS: CD4 and CD8 levels were monitored by flow cytometry. Beta2-microglobulin (beta2M) and neopterin levels were measured by quantitative enzyme immunoassays. Plasma and PBMC from 11 PR and 13 CF were analyzed for infectious HIV levels in limiting dilution cultures. Polymerase chain reaction (PCR) assays were used to quantify cellular HIV DNA and plasma HIV RNA. RESULTS: In comparison with CF, PR had little or no CD4+ cell loss, a substantial increase in CD8+ cells, significantly fewer positive plasma HIV cultures (p = .03), lower frequencies of infectious HIV in total PBMC (p = .005) and in CD4+ PBMC (p < .001), and lower frequencies of HIV DNA in CD4+ PBMC (p = .007). CONCLUSIONS: Lower levels of infectious HIV and a lower frequency of CD4+ PBMC that contain "productive" HIV DNA in PR as compared with CF may contribute to the stable or increasing CD4+ PBMC levels of the PR. However, HAART may also have effects on lymphocyte homeostasis independent of its antiviral activity.     

Frequencies of HIV-reactive B cells in seropositive and seronegative individuals.

Peripheral blood mononuclear cells (PBMC) from HIV-infected seropositive (HIV+) but not from normal, seronegative (HIV-) individuals are known to produce anti-HIV antibodies in vitro, in the absence or presence of pokeweed mitogen (PWM). Previous studies showed that up to 20-40% of spontaneously immunoglobulin-secreting B cells from HIV+ individuals are HIV-specific. To analyse the frequency of anti-HIV B cells among 'total' peripheral blood B cells in the present study, we used a limiting dilution assay in which EL-4 thymoma cells induce clones of immunoglobulin-secreting cells in activated as well as resting B cells. Anti-HIV B cells were detected not only in 11/12 HIV+ individuals (with frequencies from 1/910 to 1/21,500 B cells cultured; one negative test was from a person undergoing seroconversion), but also in 4/9 HIV- normal blood donors (1/16,200 to 1/49,000 B cells cultured) and in 3/6 newborns from HIV- mothers (1/11,800 to 1/26,600 B cells cultured). The mean frequency was nine times higher in the HIV+ individuals than in the normal donors. As in previous studies, only the cells from HIV+ individuals generated anti-HIV antibodies in PBMC bulk cultures with or without PWM. The relative proportion of specific anti-HIV antibody/total immunoglobulin in PBMC bulk cultures was 800 times higher by the mean than in EL-4 B cell cultures from HIV+ individuals (whereby the total immunoglobulin secretion for equal numbers of B cells cultured was 500 times lower for PBMC). These different results obtained with different assays suggest that in seropositives most anti-HIV B cells belong to an activated B compartment which is quite small, even in a disease with B cell hyperactivity. Therefore, the specific B cells are strongly diluted among the EL-4 cell-responsive, total B cells. On the other hand, the EL-4 assay can detect HIV-reactive B cells in the B cell repertoire of normal, non-infected individuals.     

T helper cell dysfunction in systemic lupus erythematosus (SLE): Relation to disease activity

Patients with systemic lupus erythematosus (SLE) are known to have defects in both humoral and cellular immunity. The significance of defective T cell-mediated immunity and its relationship to disease activity have not been clearly established. We studiedin vitro T helper cell (Th) function in 150 SLE outpatients and correlated Th function with validated measures of disease activity. Interleukin 2 (IL-2) production by peripheral blood mononuclear cells (PBMC) was measured after stimulation with the recall antigens influenza A virus (FLU) and tetanus toxoid (TET), irradiated allogeneic peripheral blood mononuclear cells (ALLO), and phytohemagglutinin (PHA). We observed three patterns of Th response: (1) 76 of 150 (50%) of patients responded to the recall antigens FLU and/or TET, ALLO, and PHA; (2) 62 of 150 (42%) of patients did not respond to recall antigens but responded to ALLO and PHA; and (3) 12 of 150 (8%) of patients did not respond to either recall antigens or ALLO antigens. This diminished T cell function was correlated with higher disease activity as measured by four scales of clinical activity, such that individuals who exhibited morein vitro immune dysfunction presented with significant increases in their clinical activity indicies. The alterations in T cell function could not be accounted for by medication doses alone. Thus, SLE patients have multiple distinct defects at the level of the Th cell which are associated with clinical measures of disease activity.     

Macrophages,Multinucleated Giant Cells,and Apoptosis in HIV+Patients and Normal Blood Donors

Clearance of apoptotic debris is carried out by cells of the monocyte/macrophage lineage and, as other macrophage functions, it can be altered in AIDS, leading to the accumulation of apoptotic cells observed in this disease. In this study we evaluated the ability of macrophages from human immunodeficiency virus (HIV)-infected patients to differentiate and to clear apoptotic debris in prolongedin vitrocultures. Peripheral blood mononuclear cells (PBMC) from infected hemophilia patients were cultured in the absence of exogenously added stimulators and the organization and morphological characteristics of the cultures were analyzed and correlated with clinical staging of the patients. Cell aggregates of different sizes involving macrophages and lymphocytes were formed in cultures from asymptomatic HIV⁺patients (CDC groups II–III) and controls and in 4/7 group IV C2 HIV⁺patients. In order to obtain viable and organized cultures, cells had to be handled carefully, allowing contact and undisturbed sedimentation in round-bottom tubes. Multinucleated giant cells (MGC) were formed through macrophage fusion after 5 days of culture in HIV⁻controls, group II and III patients, and some of the group IV C2 patients, while scarce formation of MGC was observed in AIDS patients or patients with advanced HIV disease. This paucity was correlated with impaired dead cell removal and accumulation of apoptotic debris. Viability of macrophages and MGC was reduced after 15 days. MGC and the macrophages (either free or in cell aggregates) were able to remove dead cells, clearing the cultures of cell debris. Furthermore, in group II and III HIV⁺hemophilic patients, increased macrophage–MGC phagocytic activity, suggestingin vivoactivation, was frequently observed. In HIV⁺patients with AIDS or advanced HIV disease (CDC groups IV A, IV C1, and IV D) dead cell removal was impaired and apoptotic debris accumulated. Long-term cultures of unstimulated PBMC are an interesting model for studying the role of macrophages and/or MGC in the removal of dead cells as well as examining the cellular milieu in which HIV replicates in an individual host.     

Expression of Regeneration and Tolerance Factor Correlates Directly with Human Immunodeficiency Virus Infection and Inversely with Hepatitis C Virus Infection

Hepatitis C virus (HCV) and human immunodeficiency virus (HIV) cause two of the most prevalent debilitating viral infections. HIV appears to induce a skewing toward a Th2 response, while in HCV infection a Th1 response appears to dominate. Regeneration and tolerance factor (RTF) may participate in driving or sustaining a Th2 cytokine response. The expression of RTF on CD3⁺ T cells of HIV-seropositive (HIV⁺) individuals is increased. The purpose of this study was to compare the expression of RTF during HIV infections with that during HCV infections. Three-color flow-cytometric analysis of peripheral blood collected from HIV⁺ HCV-seropositive (HCV⁺), HIV- and HCV-seropositive (HIV⁺ HCV⁺), and HIV- and HCV-seronegative (HIV⁻ HCV⁻) individuals was performed. Levels of RTF expression on T-lymphocyte subsets from these groups were compared, as were levels of RTF expression on activated T cells expressing CD38 and HLA-DR, to determine the relationship of RTF expression to these infections. We demonstrated that the expression of RTF on surfaces of T cells from HIV⁺ individuals is upregulated and that its expression on T cells from HCV⁺ individuals is downregulated. A twofold increase in the mean channel fluorescence of RTF on CD3⁺ T cells was seen in both HIV⁺ and HIV⁺ HCV⁺ individuals compared to HIV⁻ HCV⁻ individuals. HCV⁺ individuals had lower levels of RTF expression than HIV⁻ HCV⁻ individuals (P < 0.005 for CD4⁺; P < 0.0005 for CD8⁺). In terms of percentages of T cells expressing RTF, the groups were ranked as follows: HIV⁺ > HIV⁺ HCV⁺ > HIV⁻ HCV⁻ > HCV⁺. The results indicate that RTF expression correlates with HIV-associated immune activation and may be associated with Th2-type responses.     

Individual variation in the frequency of HLA class II-specific cytotoxic T lymphocyte precursors

The frequencies of HLA class II-specific cytotoxic T lymphocyte precursors (CTLp) were studied in number of unrelated individuals using a limiting dilution analysis system optimized for the detection of CD4+ CTLp. Peripheral blood mononuclear cells (PBMC) were enriched for CD4+ T cells by immunomagnetic depletion of CD8+ T cells. In some allogeneic combinations high CTLp frequencies were obtained with no significant difference between PBMC and CD4-enriched PBMC populations. In other combinations CTLp frequencies in CD4-enriched PBMC were found to be at least twentyfold lower than in the starting, unfractionated PBMC, suggesting a predominance in these pairs of CD8+ CTLp. In addition there was variation in CTLp frequencies against the same set of HLA class II gene products between individuals, and variation in CTLp frequencies against different HLA class II gene products within individuals. The HLA class II specificity of the assay system was demonstrated unequivocally with detection of CTLp against HLA-DR1 expressed on a murine L cell transfectant.     

Tumour necrosis factor (TNF) and TNF-related molecules in HIV-1+ individuals: relationship with in vitro Thl/Th2-type response

We examined the secretion and expression by peripheral blood mononuclear cells (PBMC) of TNF-α and TNF-related molecules with regard to Th1/Th2-type cytokine production. In 76 HIV⁺ patients at different disease stages and in 25 controls we measured cytokine (TNF-α/β, interferon-gamma (IFN-γ), IL-2, IL-4, IL-10), and activation marker secretion (sCD4, sCD8, sCD30) in phytohaemagglutinin (PHA)-stimulated and unstimulated PBMC cultures by ELISA, and membrane-bound TNF-α and CD30 expression by flow cytometry. We found an expansion of the TNF system in HIV⁺ individuals, that positively correlated with TNF-α, IFN-γ and sCD8, probably representing activation of the cytotoxic compartment. In advanced disease these correlations disappeared, and TNF-α and TNF-related molecules positively correlated with IL-10. Our results are in line with the hypothesis that an expanded TNF system is immunopathological in conjunction with Th2-type immunity in the advanced stage of disease and with the inexorable progression to disease seen when both IL-10 and TNF-α are elevated.     

Co-receptor and co-stimulation blockade for mixed chimerism and tolerance without myelosuppressive conditioning

Background

For immune monitoring studies during HIV vaccine clinical trials, whole blood specimens from HIV seropositive (HIV⁺) patients may be collected at multiple sites and sent to a central location for peripheral blood mononuclear cell (PBMC) isolation, cryopreservation and functional evaluation. In this study we show a comparison of two PBMC preparation options, Ficoll density gradient separation (Ficoll) and Cell Preparation Tubes (CPT) using shipped whole blood specimens from 19 HIV⁺ patients (CD4 > 350, viral load < 50). The pre- and post- cryopreservation performance of samples collected by these two methods were compared by assessment of antigen-specific IFNγ expression in CD8⁺ and CD8^- T cells, cellular viability, and cellular recovery.

Results

The results indicate that cryopreserved PBMC samples tested for CMV- and HIV- specific interferon-gamma (IFNγ) expression performed equivalent to the respective fresh PBMC processed under both collection conditions. Compared to fresh PBMC, the viability was significantly lower for cryopreserved PBMC derived using Ficoll, although it was never less than 90%. There were no significant differences in the IFNγ response, viability, or recovery between cryopreserved PBMC derived by Ficoll and by CPT.

Conclusion

These data suggest that CPT is an efficient system for the collection and cryopreservation of functionally active HIV⁺ PBMC, as well as a viable alternative to Ficoll gradient separation.     

Dysregulated production of interleukin-10 (IL-10) and IL-12 by peripheral blood lymphocytes from human immunodeficiency virus-infected individuals is associated with altered proliferative responses to recall antigens.

The loss of immune function following infection with human immunodeficiency virus (HIV) may result from altered production of immunoregulatory cytokines such as interleukin-10 (IL-10) and IL-12. In this study, we analyzed IL-10 and IL-12 production by mitogen-stimulated peripheral blood mononuclear cells (PBMC) from HIV+ individuals and correlated their levels with proliferative responses to the recall antigens HIV p25 and influenza virus. We report two distinct groups of HIV+ patients. One group produced small amounts of IL-10, had PBMC that proliferated in response to recall antigens, and demonstrated enhanced recall antigen-induced proliferation upon addition of anti-IL-10 antibodies and/or IL-12. Conversely, the second group produced high levels of IL-10, had PBMC that failed to proliferate to recall antigens, and did not demonstrate enhanced proliferation upon addition of anti-IL-10 antibodies and/or IL-12. Mitogen-stimulated PBMC from both groups produced significantly lower levels of IL-12 than did those from HIV- controls. Analysis of the source of the IL-10-producing cell subset in PBMC demonstrated that in HIV+ individuals, IL-10 is produced by monocytes, while in HIV- controls, it is produced by both T cells and monocytes. Taken together, our results suggest that monocytes from HIV+ individuals secrete decreased amounts of IL-12, a Th1-type cytokine, which may lead to the development of Th2-type responses characterized by high IL-10 secretion and immune dysfunction.     

Limiting dilution analysis of specific in vitro anti-herpes simplex virus antibody production by human lymphocytes.

An enzyme linked immunosorbent assay (ELISA) system to study specific anti-herpes simplex virus (HSV) antibody production in vitro by human peripheral blood mononuclear cells (PBMC) has been developed. HSV specific antibody production was detected in culture supernatants of PBMC from HSV seropositive healthy individuals by stimulating with optimal concentrations of HSV antigen without mitogens. To investigate the specificity of the resulting antibody, a limiting dilution analysis was performed as follows. PBMC from HSV-1 seropositive and HSV-2 seronegative individuals were stimulated by wild type HSV-1 (KOS), glycoprotein C deletion mutant of HSV-1 (MP), and wild type HSV-2 (186), and the precursor frequencies of B cells which produce antibodies to HSV-1 (KOS), HSV-1 (MP) and HSV-2 (186) were then estimated. When PBMC from five individuals were stimulated by HSV-1 (KOS), the estimated precursor frequencies of B cells which produced antibodies to HSV-1 (KOS), HSV-1 (MP), and HSV-2 (186) were 1/79,000 to 1/37,000, 1/104,000 to 1/52,000. and 1/78,000 to 1/101,000, respectively. On the other hand, when PBMC were stimulated by HSV-1 (MP) and HSV-2 (186), the precursor frequencies of B cells which produced antibody to HSV-1 (KOS) were the same as those to HSV-1 (MP) and HSV-2 (186), respectively. By using the experimental systems reported here, it became possible to determine clearly the immune status to HSV type-specific and type-common antigens and to each viral glycoprotein.     

Changes to the cytokine microenvironment in the genital tract mucosa of HIV+ women

As previous studies have indicated that genital tract mucosal T cell function may be impaired in HIV infection, we investigated the T cell cytokine mRNA in the genital tract mucosa of HIV-infected women to determine if there are alterations in the cytokine profile which may explain the T cell impairment. The in situ hybridization technique was used to investigate the T helper-1 (Th1: IL-2, interferon-gamma (IFN-γ)) and Th2 cytokine (IL-4, IL-5, IL-10) mRNA profile in cervical biopsies from 10 HIV⁺ and 10 HIV^? subjects. Cervical intraepithelial neoplasia (CIN) and genital infection had previously been excluded and the distribution of immunocompetent cells within the cervical mucosa was known for each subject. Non-parametric tests were used to compare the optical density (OD) of cytokine mRNA in the HIV⁺ and HIV^? groups. Comparisons were also made between peripheral CD4 lymphocyte counts, cervical CD4/CD8 T lymphocyte ratios and cytokine mRNA OD in HIV⁺ subjects. The HIV⁺ women had significantly higher mRNA OD for the Th2 cytokines IL-4, IL-5 and IL-10 than HIV^? women. There was also significantly lower IL-2 mRNA OD in the former group. HIV⁺ women had lower IFN-γ mRNA than HIV^? women, but the difference was not statistically significant. There was no correlation between cytokine mRNA OD and peripheral CD4 count or cervical CD4/CD8 ratio. The predominance of Th2 cytokines, which are immuno-inhibitory, in the cervical mucosa of HIV⁺ women may underlie the impaired cytotoxic potential observed in the CD8⁺ T lymphocytes and may contribute to the susceptibility of HIV-infected women to recurrent genital tract infections and cervical neoplasia.     

Frequencies of T cells secreting IL-2 and/or IL-4 among unprimed CD4+ populations. Evidence that clones secreting IL-2 and IL-4 give rise to clones which secrete only IL-4

We have utilized a limiting dilution assay, involving a minimum of in vitro culture, to determine the frequencies of CD4+ T cells which have the capacity to secrete IL-2 (Th1), IL-4 (Th2) or IL-2 and IL-4 (Th0). CD4+ lymph node cells obtained from unimmunized mice were found to contain 40% Th1, 34% Th2, and 26% Th0 cells. The fact that Th0 cells could be identified in cell populations obtained from unimmunized mice suggested a possible role for Th0 in the differentiation pathways of Th1 and Th2. Antigen-specific Th0 clones were thus established and observed to convert to a Th2 phenotype after prolonged culture. The relevance of these findings is discussed in the context of current models of CD4+ T cell subsets.     

CD40 ligand and IFN-γ synergistically restore IL-12 production in HIV-infected patients

IL-12 production in HIV-infected (HIV⁺) individuals is severely impaired after stimulation by bacterial products or T cell-dependent stimuli. Because CD40-CD40 ligand (CD40L) interactions are the major mechanism involved in the T cell-dependent activation of antigen-presenting cells, we investigated whether this pathway was functional in HIV⁺ donors. CD40 expression was increased on freshly isolated monocytes from HIV⁺ individuals compared to HIV⁻ donors. However, equivalent CD40 expression was obtained in the two groups after cytokine stimulation. Since CD40 expression was intact in HIV⁺ donors' cells, we determined whether IL-12 production could be restored by providing exogenous T cell-dependent stimuli, CD40L and IFN-γ, at the time of bacterial stimulation. IL-12 production was not altered by CD40L alone, was increased by IFN-γ, and was synergistically restored to normal values by IFN-γ + CD40L. This combination was more efficient for enhancing IL-12 production than granulocyte-macrophage colony-stimulating factor + CD40L or neutralizing anti-IL-10 antibody + CD40L. CD40L did not affect IL-10 production, whereas IFN-γ significantly decreased it. This study demonstrates that the defect in IL-12 production by leukocytes from HIV⁺ donors can be overcome in vitro if the interacting cells are provided with the right T cell-dependent co-stimuli.     

Leishmania-specific T cells expressing interferon-gamma (IFN-gamma) and IL-10 upon activation are expanded in individuals cured of visceral leishmaniasis.

Peripheral blood mononuclear cells (PBMC) from patients who have recovered from visceral leishmaniasis often respond to Leishmania antigens in vitro by production of both IL-4, IFN-gamma and IL-10. In order to establish the cellular sources of these cytokines, we activated cells from individuals with a history of visceral leishmaniasis with Leishmania antigen for 6 days in culture, and identified cytokine production at the single-cell level by flow cytometry. The cytokines were only found in CD3+ cells and among these mainly within the CD4+ subset. The percentage of cytokine-producing cells was compared in Leishmania-activated PBMC cultures from the previous patients and from individuals living in a village where leishmaniasis does not occur. The percentage of IL-10- and IFN-gamma-containing cells was significantly higher in the previous patients than in the controls, indicating that Leishmania-specific T cells producing IL-10 and/or IFN-gamma had been expanded as a result of the infection. The cytokine-producing cells in the previous patients could be divided into three types: (i) cells producing IFN-gamma only; (ii) cells producing IL-4 only; and (iii) cells producing IFN-gamma and IL-10 simultaneously. The first and second group of cells can be described as Th1- and Th2-type cells, respectively. The third group could be a regulatory subset of T cells important for maintaining a balance between Th1- and Th2-type cells in these individuals.     

Lymph nodes from HIV-infected individuals harbor mature dendritic cells and increased numbers of PD-L1+ conventional dendritic cells

The immune response induced by dendritic cells (DC) during the HIV infection has been of remarkable interest because of the therapeutic potential of DC for vaccine development. However, their beneficial or detrimental contribution in HIV infection remains unclear. The activation state of DC in lymph nodes (LN) is essential to induce T cell responses against HIV. In the present study, we characterized the immunophenotype and function of conventional (cDC) and plasmacytoid (pDC) dendritic cells from peripheral blood (PB) and LN of HIV⁺ individuals. We observed that the frequency of PB pDC was decreased and exhibited an immature phenotype; whereas in the LN, activated pDC accumulated (CD40⁺ and CD83⁺). In addition, the frequency of PB cDC from HIV⁺ individuals was decreased and exhibited an immature phenotype, whereas LN harbored activated and mature cDC (CD40⁺, CD83⁺, CD80⁺ and CD86⁺). However, an increased number of PD-L1⁺ cDC was also observed in the LN. Moreover, pDC and cDC were able to produce inflammatory cytokines (IFN-α, TNF-α and IL-12) after TLR stimulation. These findings suggests that LN cDC expressing PD-L1 from HIV⁺ individuals may negatively impact the generation of HIV-specific T cells and that DC might be contributing to tissue chronic immune activation.     

Divergent regulation of HIV-1 replication in PBMC of infected individuals by CC chemokines: suppression by RANTES, MIP-1alpha, and MCP-3, and enhancement by MCP-1

We investigated the role of different CC chemokines, including regulated upon activation normal T cell expressed and secreted (RANTES), macrophage inflammatory protein-lalpha (MIP-1alpha), monocyte chemotactic protein-1 (MCP-1), and MCP-3 on virus replication in cultures established from CD8+ T cell-depleted peripheral blood mononuclear cells (PBMC) of HIV-infected individuals that were either cocultivated with allogeneic T cell blasts (ATCB) of uninfected individuals or directly stimulated by mitogen plus interleukin-2. RANTES was the only chemokine that showed a clear-cut suppressive effect on HIV replication in both culture systems, although inhibitory effects were frequently also observed with MIP-1alpha, MCP-3, and, occasionally, with MCP-1. In contrast, MCP-1 frequently enhanced HIV production in most patients' cultures or cocultures that were characterized by secreting relatively low levels (<20 ng/mL) of MCP-1. When CD8-depleted PBMC of HIV+ individuals were cocultivated with ATCB of uninfected healthy donors, a positive correlation was observed between MCP-1 concentrations and the enhancement of HIV-1 replication occurring after depletion of CD8+ cells from donors' cells. Depletion of CD14+ cells (monocytes) from ATCB resulted in the down-regulation of virus replication during co-cultivation with CD8-depleted PBMC of infected individuals. Of interest, MCP-1 up-regulated HIV production in these CD14-depleted ATCB cocultures. Altogether these observations suggest that MCP-1 may represent an important factor enhancing HIV spreading, particularly in anatomical sites, such as the brain, where infection of macrophages and microglial cells plays a dominant role.     

NK cells are primed by ANRS MVAHIV‐infected DCs,via a mechanism involving NKG2D and membrane‐bound IL‐15, to control HIV‐1 infection in CD4+ T cells

Natural killer (NK) cells are the major antiviral effector cell population of the innate immune system. It has been demonstrated that NK‐cell activity can be modulated by the interaction with dendritic cells (DCs). The HIV‐1 vaccine candidate Modified Vaccinia Ankara encoding an HIV polypeptide (MVA_HIV), developed by the French National Agency for Research on AIDS (ANRS), has the ability to prime NK cells to control HIV‐1 infection in DCs. However, whether or not MVA_HIV‐primed NK cells are able to better control HIV‐1 infection in CD4⁺ T cells, and the mechanism underlying the specific priming, remain undetermined. In this study, we show that MVA_HIV‐primed NK cells display a greater capacity to control HIV‐1 infection in autologous CD4⁺ T cells. We also highlight the importance of NKG2D engagement on NK cells and DC‐produced IL‐15 to achieve the anti‐HIV‐1 specific priming, as blockade of either NKG2D or IL‐15 during MVA_HIV‐priming lead to a subsequent decreased control of HIV‐1 infection in autologous CD4⁺ T cells. Furthermore, we show that the decreased control of HIV‐1 infection in CD4⁺ T cells might be due, at least in part, to the decreased expression of membrane‐bound IL‐15 (mbIL‐15) on DCs when NKG2D is blocked during MVA_HIV‐priming of NK cells.     

Cytologic features of mycobacterial pleuritis: logistic regression and statistical analysis of a blinded,case-controlled study

Tuberculous pleural effusions are characterized by lymphocytosis; the significance of mesothelial cells is uncertain, as are the cytologic features in concurrent human immunodeficiency virus (HIV) infection. This blinded study compared 38 culture-positive pleural fluids (6 HIV⁺) with 38 controls from benign exudative processes. Logistic regression analysis selected mature lymphocytes as most predictive of positive culture, and mesothelial cells and eosinophils as negative predictors. Mesothelial cells were scant (<10% of nucleated cells) in 36/38 cases with mycobacteria (sensitivity 95%); if these cells were <10%, tuberculosis was virtually ruled out in HIV⁻ patients. Specificity was maximized (82%) when mesothelial cells <10% were combined with lymphocytes <50%; positive predictive value with this combination was 76%, but was raised to 96% if moderate/marked cellularity was also identified. Among tuberculosis cases, reactive mesothelial cells differentiated HIV⁺ from HIV⁻ patients; there was no other significant difference. Diagn. Cytopathol. 1998;19:173–176. © 1998 Wiley-Liss, Inc.     

Differential production of IL-10 by T cells and monocytes of HIV-infected individuals: association of IL-10 production with CD28-mediated immune responsiveness

Immune unresponsiveness in HIV-1 infection can result from impaired signals delivered by the costimulatory CD28-B7 pathway and the altered production of immunoregulatory cytokines, in particular IL-10, whose production is altered in HIV-1 infection. In this study we investigate IL-10 regulation in T cells and monocytes from HIV⁺ individuals, and its association with CD28-mediated T cell proliferation. IL-10 production as analysed in T cell- and monocyte-depleted peripheral blood mononuclear cells (PBMC), and by intracellular staining at the single-cell level, reveals a defect in IL-10 production by CD4⁺ and CD8⁺ T cells, whereas monocytes constitute the major IL-10-producing cell type. To investigate the impact of IL-10 on immune responsiveness, CD28-mediated proliferative responses in HIV⁺ individuals were correlated with PHA-induced IL-10 production. CD4⁺ T cells expressed CD28, yet exhibited markedly reduced CD28-mediated cell proliferation. This CD28-mediated CD4⁺ T cell proliferation was found to be inversely associated with the levels of PHA-induced IL-10 production and could be restored, at least in part, by anti-IL-10 antibodies. These results suggest that IL-10 production is differentially regulated in T cells and monocytes of HIV⁺ individuals, and that IL-10 may have a role in inducing immune unresponsiveness by modulating the CD28-B7 pathway.