Antigen presentation capacity and cytokine production by murine splenic dendritic cell subsets upon Salmonella encounter

Salmonella typhimurium is an intracellular bacterium that replicates in the spleen and mesenteric lymph nodes (MLN) of orally infected mice. However, little is known about the Ag presentation and cytokine production capacity of dendritic cells (DC), particularly CD8alpha(+), CD8alpha(-)CD4(-), and CD8alpha(-)CD4(+) DC, from these organs in response to SALMONELLA: Infection of purified splenic DC with S. typhimiurium expressing green fluorescent protein (GFP) and OVA revealed that all three splenic DC subsets internalize bacteria, and splenic as well as MLN DC process Salmonella for peptide presentation. Furthermore, presentation of Salmonella Ags on MHC-I and MHC-II was evident in both CD8alpha(+) and CD8alpha(-) splenic DC subsets. Direct ex vivo analysis of splenic DC from mice infected with GFP-expressing Salmonella showed that all three subsets harbored bacteria, and splenic DC purified from mice given Salmonella-expressing OVA presented OVA-derived peptides on MHC-I and MHC-II. Cytokine production analyzed by intracellular staining of splenic DC infected with GFP-expressing Salmonella revealed that TNF-alpha was produced by a large percentage of CD8alpha(-) DC, while only a minor proportion of CD8alpha(+) DC produced this cytokine following bacterial exposure. In contrast, the greatest number of IL-12p40-producing DC were among CD8alpha(+) DC. Experiments inhibiting bacterial uptake by cytochalasin D as well as use of a Transwell system revealed that bacterial contact, but not internalization, was required for cytokine production. Thus, DC in sites of Salmonella replication and T cell activation, spleen and MLN, respond to bacterial encounter by Ag presentation and produce cytokines in a subset-specific fashion.     

Endogenous granulocyte-macrophage colony-stimulating factor overexpression in vivo results in the long-term recruitment of a distinct dendritic cell population with enhanced immunostimulatory function

GM-CSF is critical for dendritic cell (DC) survival and differentiation in vitro. To study its effect on DC development and function in vivo, we used a gene transfer vector to transiently overexpress GM-CSF in mice. We found that up to 24% of splenocytes became CD11c+ and the number of DC increased up to 260-fold to 3 x 10(8) cells. DC numbers remained substantially elevated even 75 days after treatment. The DC population was either CD8alpha+CD4- or CD8alpha-CD4- but not CD8alpha+CD4+ or CD8alpha-CD4+. This differs substantially from subsets recruited in normal or Flt3 ligand-treated mice or using GM-CSF protein injections. GM-CSF-recruited DC secreted extremely high levels of TNF-alpha compared with minimal amounts in DC from normal or Flt3 ligand-treated mice. Recruited DC also produced elevated levels of IL-6 but almost no IFN-gamma. GM-CSF DC had robust immune function compared with controls. They had an increased rate of Ag capture and caused greater allogeneic and Ag-specific T cell stimulation. Furthermore, GM-CSF-recruited DC increased NK cell lytic activity after coculture. The enhanced T cell and NK cell immunostimulation by GM-CSF DC was in part dependent on their secretion of TNF-alpha. Our findings show that GM-CSF can have an important role in DC development and recruitment in vivo and has potential application to immunotherapy in recruiting massive numbers of DC with enhanced ability to activate effector cells.     

Two phenotypically distinct subsets of spleen dendritic cells in rats exhibit different cytokine production and T cell stimulatory activity

We recently reported that splenic dendritic cells (DC) in rats can be separated into CD4(+) and CD4(-) subsets and that the CD4(-) subset exhibited a natural cytotoxic activity in vitro against tumor cells. Moreover, a recent report suggests that CD4(-) DC could have tolerogenic properties in vivo. In this study, we have analyzed the phenotype and in vitro T cell stimulatory activity of freshly isolated splenic DC subsets. Unlike the CD4(-) subset, CD4(+) splenic DC expressed CD5, CD90, and signal regulatory protein alpha molecules. Both fresh CD4(-) and CD4(+) DC displayed an immature phenotype, although CD4(+) cells constitutively expressed moderate levels of CD80. The half-life of the CD4(-), but not CD4(+) DC in vitro was extremely short but cells could be rescued from death by CD40 ligand, IL-3, or GM-CSF. The CD4(-) DC produced large amounts of the proinflammatory cytokines IL-12 and TNF-alpha and induced Th1 responses in allogeneic CD4(+) T cells, whereas the CD4(+) DC produced low amounts of IL-12 and no TNF-alpha, but induced Th1 and Th2 responses. As compared with the CD4(+) DC that strongly stimulated the proliferation of purified CD8(+) T cells, the CD4(-) DC exhibited a poor CD8(+) T cell stimulatory capacity that was substantially increased by CD40 stimulation. Therefore, as previously shown in mice and humans, we have identified the existence of a high IL-12-producing DC subset in the rat that induces Th1 responses. The fact that both the CD4(+) and CD4(-) DC subsets produced low amounts of IFN-alpha upon viral infection suggests that they are not related to plasmacytoid DC.     

TNF-alpha-dependent and -independent maturation of dendritic cells and recruited CD11c(int)CD11b+ Cells during oral Salmonella infection

Maturation of dendritic cells (DC) is crucial for their ability to induce adaptive immunity. Although several mediators of DC maturation have been found, their contributions to DC maturation during infection are poorly understood. In this study we show that murine conventional (CD11c(high)) DC up-regulate costimulatory molecules in a subset-specific manner after oral Salmonella infection. Although both CD8alpha+ and CD8alpha- subsets increase CD86 expression, CD40 was preferentially up-regulated on CD8alpha+ DC, and CD80 was preferentially increased on CD8alpha- DC. In addition, high levels of CD80 and CD86 were found on CD11c(int)CD11b+ cells that accumulated in infected organs. Costimulatory molecules were simultaneously induced on CD11c(high) and CD11c(int)CD11b+ cells in Peyer's patches, mesenteric lymph nodes and spleen 5 days after infection despite different kinetics of peak bacterial burden in these organs. Up-regulation of costimulatory molecules occurred on all DC within the respective subset. Moreover, <1% of CD11c-expressing cells associated with Salmonella expressing enhanced GFP in vivo. Thus, DC maturation did not depend on bacterial uptake. Rather, infection-induced up-regulation of CD80, CD86, and CD40 on CD11c-expressing cells of mesenteric lymph nodes was dependent on TNFR type I (TNFRI) signaling. Although indirect up-regulation of costimulatory molecules on DC and CD11c(int)CD11b+ cells was TNFRI dependent, cells directly associated with Salmonella were able to mature independently of TNFRI signaling. Thus, Salmonella-induced TNF-alpha is an important mediator of indirect DC maturation during infection, whereas a TNF-alpha-independent maturation pathway contributes to direct maturation of bacteria-associated DC.     

Distinct subsets of dendritic cells regulate the pattern of acute xenograft rejection and susceptibility to cyclosporine therapy

We determined whether distinct subclasses of dendritic cells (DC) could polarize cytokine production and regulate the pattern of xenograft rejection. C57BL/6 recipients, transplanted with Lewis rat hearts, exhibited a predominantly CD11c(+)CD8alpha(+) splenic DC population and an intragraft cytokine profile characteristic of a Th1-dominant response. In contrast, BALB/c recipients of Lewis rat heart xenografts displayed a predominantly CD11c(+)CD8alpha(-) splenic DC population and IL-4 intragraft expression characteristic of a Th2 response. In addition, the CD11c(+)IL-12(+) splenic DC population in C57BL/6 recipients was significantly higher than that in BALB/c recipients. Adoptive transfer of syngeneic CD8alpha(-) bone marrow-derived DC shifted a Th1-dominant, slow cell-mediated rejection to a Th2-dominant, aggressive acute vascular rejection (AVR) in C57BL/6 mice. This was associated with a cytokine shift from Th1 to Th2 in these mice. In contrast, transfer of CD8alpha(+) bone marrow-derived DC shifted AVR to cell-mediated rejection in BALB/c mice and significantly prolonged graft survival time from 6.0 +/- 0.6 days to 14.2 +/- 0.8 days. CD8alpha(+) DC transfer rendered BALB/c mice susceptible to cyclosporine therapy, thereby facilitating long-term graft survival. Furthermore, CD8alpha(+) DC transfer in IL-12-deficient mice reconstituted IL-12 expression, induced Th1 response, and attenuated AVR. Our data suggest that the pattern of acute xenogeneic rejection can be regulated by distinct DC subsets.     

Immune evasion by Yersinia enterocolitica: differential targeting of dendritic cell subpopulations in vivo

CD4(+) T cells are essential for the control of Yersinia enterocolitica (Ye) infection in mice. Ye can inhibit dendritic cell (DC) antigen uptake and degradation, maturation and subsequently T-cell activation in vitro. Here we investigated the effects of Ye infection on splenic DCs and T-cell proliferation in an experimental mouse infection model. We found that OVA-specific CD4(+) T cells had a reduced potential to proliferate when stimulated with OVA after infection with Ye compared to control mice. Additionally, proliferation of OVA-specific CD4(+) T cells was markedly reduced when cultured with splenic CD8α(+) DCs from Ye infected mice in the presence of OVA. In contrast, T-cell proliferation was not impaired in cultures with CD4(+) or CD4(-)CD8α(-) DCs isolated from Ye infected mice. However, OVA uptake and degradation as well as cytokine production were impaired in CD8α(+) DCs, but not in CD4(+) and CD4(-)CD8α(-) DCs after Ye infection. Pathogenicity factors (Yops) from Ye were most frequently injected into CD8α(+) DCs, resulting in less MHC class II and CD86 expression than on non-injected CD8α(+) DCs. Three days post infection with Ye the number of splenic CD8α(+) and CD4(+) DCs was reduced by 50% and 90%, respectively. The decreased number of DC subsets, which was dependent on TLR4 and TRIF signaling, was the result of a faster proliferation and suppressed de novo DC generation. Together, we show that Ye infection negatively regulates the stimulatory capacity of some but not all splenic DC subpopulations in vivo. This leads to differential antigen uptake and degradation, cytokine production, cell loss, and cell death rates in various DC subpopulations. The data suggest that these effects might be caused directly by injection of Yops into DCs and indirectly by affecting the homeostasis of CD4(+) and CD8α(+) DCs. These events may contribute to reduced T-cell proliferation and immune evasion of Ye.     

Adoptive transfer of CD8alpha+ dendritic cells (DC) isolated from mice infected with Chlamydia muridarum are more potent in inducing protective immunity than CD8alpha- DC

Chlamydial infections are serious public health concerns worldwide. In this study, we examined the role of dendritic cell (DC) subsets in inducing protective immunity against chlamydial infection using an adoptive transfer approach. We found that CD11c+CD8alpha+ (double-positive, DP) DC, compared with CD11c+CD8alpha- (single-positive, SP) DC isolated from infected mice, are more potent inducers of protective immunity. Specifically, mice pretreated with DPDC from infected mice, upon infection with Chlamydia trachomatis mouse pneumonitis (MoPn), experienced significantly less severe body weight loss and in vivo chlamydial growth. Analysis of MoPn-driven cytokine production by immune cells revealed that mice that were treated with DPDC produced significantly higher levels of Th1 (TNF-alpha, IFN-gamma, and IL-12) but lower levels of Th2 (IL-4, IL-5, and IL-13)-related cytokines than the recipients of SPDC following infection challenge. Moreover, DPDC-treated mice displayed significantly higher levels of MoPn-specific IgG2a production and delayed-type hypersensitivity responses compared with SPDC-treated mice. Furthermore, DPDC isolated from infected mice produced higher amounts of IL-12 and IL-10 in vitro in comparison with SPDC. These data indicate that CD8alpha+ DC have a significantly higher capacity in inducing protective immunity compared with CD8alpha- DC, demonstrating the crucial role of DC1-like cells in eliciting protection against C. trachomatis infection.     

Cytokine production by mature and immature CD4-CD8- T cells. Alpha beta-T cell receptor+ CD4-CD8- T cells produce IL-4.

This study follows our previous investigation describing the production of four cytokines (IL-2, IL-4, IFN-gamma, and TNF-alpha) by subsets of thymocytes defined by the expression of CD3, 4, 8, and 25. Here we investigate in greater detail subpopulations of CD4-CD8- double negative (DN) thymocytes. First we divided immature CD25-CD4-CD8-CD3- (CD25- triple negative) (TN) thymocytes into CD44+ and CD44- subsets. The CD44+ population includes very immature precursor T cells and produced high titers of IL-2, TNF-alpha, and IFN-gamma upon activation with calcium ionophore and phorbol ester. In contrast, the CD44- subset of CD25- TN thymocytes did not produce any of the cytokines studied under similar activation conditions. This observation indicates that the latter subset, which differentiates spontaneously in vitro into CD4+CD8+, already resembles CD4+CD8+ thymocytes (which do not produce any of the tested cytokines). We also subdivided the more mature CD3+ DN thymocytes into TCR-alpha beta- and TCR-gamma delta-bearing subsets. These cells produced cytokines upon activation with solid phase anti-CD3 mAb. gamma delta TCR+ DN thymocytes produced IL-2, IFN-gamma and TNF-alpha, whereas alpha beta TCR+ DN thymocytes produced IL-4, IFN-gamma, and TNF-alpha but not IL-2. We then studied alpha beta TCR+ DN T cells isolated from the spleen and found a similar cytokine production profile. Furthermore, splenic alpha beta TCR+ DN cells showed a TCR V beta gene expression profile reminiscent of alpha beta TCR+ DN thymocytes (predominant use of V beta 8.2). These observations suggest that at least some alpha beta TCR+ DN splenocytes are derived from alpha beta TCR+ DN thymocytes and also raises the possibility that these cells may play a role in the development of Th2 responses through their production of IL-4.     

CD154 plays a central role in regulating dendritic cell activation during infections that induce Th1 or Th2 responses

We compared splenic DC activation during infection with either the Th2 response-inducing parasite Schistosoma mansoni or with the Th1 response-inducing parasite Toxoplasma gondii. CD8alpha(+) DC from schistosome-infected mice exhibited a 2- to 3-fold increase in the expression of MHC class II, CD80, and CD40 (but not CD86) compared with DC from uninfected control animals, while CD8alpha(-) DC exhibited a 2- to 3-fold increase in the expression of MHC class II and CD80 and no alteration, compared with DC from uninfected mice, in the expression of CD86 or CD40. Intracellular staining revealed that DC did not produce IL-12 during infection with S. mansoni. In contrast, infection with T. gondii resulted in a more pronounced increase in the expression of activation-associated molecules (MHC class II, CD80, CD86, and CD40) on both CD8alpha(-) and CD8alpha(+) splenic DC and promoted elevated IL-12 production by DC. Analysis of MHC class I and of additional costimulatory molecules (ICOSL, ICAM-1, OX40L, 4-1BBL, and B7-DC) revealed a generally similar pattern, with greater indication of activation in T. gondii-infected mice compared with S. mansoni-infected animals. Strikingly, the activation of DC observed during infection with either parasite was not apparent in DC from infected CD154(-/-) mice, indicating that CD40/CD154 interactions are essential for maintaining DC activation during infection regardless of whether the outcome is a Th1 or a Th2 response. However, the ability of this activation pathway to induce IL-12 production by DC is restrained in S. mansoni-infected, but not T. gondii-infected, mice by Ag-responsive CD11c(-) cells.     

Liver dendritic cells are less immunogenic than spleen dendritic cells because of differences in subtype composition

The unique immunological properties of the liver may be due to the function of hepatic dendritic cells (DC). However, liver DC have not been well characterized because of the difficulty in isolating adequate numbers of cells for analysis. Using immunomagnetic bead and flow cytometric cell sorting, we compared freshly isolated murine liver and spleen CD11c+ DC. We found that liver DC are less mature, capture less Ag, and induce less T cell stimulation than spleen DC. Nevertheless, liver DC were able to generate high levels of IL-12 in response to CpG stimulation. We identified four distinct subtypes of liver DC based on the widely used DC subset markers CD8alpha and CD11b. Lymphoid (CD8alpha+CD11b-) and myeloid (CD8alpha-CD11b+) liver DC activated T cells to a similar degree as did their splenic DC counterparts but comprised only 20% of all liver DC. In contrast, the two more prevalent liver DC subsets were only weakly immunostimulatory. Plasmacytoid DC (B220+) accounted for 19% of liver DC, but only 5% of spleen DC. Our findings support the widely held notion that liver DC are generally weak activators of immunity, although they are capable of producing inflammatory cytokines, and certain subtypes potently activate T cells.     

Cutting edge: generation of splenic CD8+ and CD8- dendritic cell equivalents in Fms-like tyrosine kinase 3 ligand bone marrow cultures

We demonstrate that functional and phenotypic equivalents of mouse splenic CD8(+) and CD8(-) conventional dendritic cell (cDC) subsets can be generated in vitro when bone marrow is cultured with fms-like tyrosine kinase 3 (flt3) ligand. In addition to CD45RA(high) plasmacytoid DC, two distinct CD24(high) and CD11b(high) cDC subsets were present, and these subsets showed equivalent properties to splenic CD8(+) and CD8(-) cDC, respectively, in the following: 1) surface expression of CD11b, CD24, and signal regulatory protein-alpha; 2) developmental dependence on, and mRNA expression of, IFN regulatory factor-8; 3) mRNA expression of TLRs and chemokine receptors; 4) production of IL-12 p40/70, IFN-alpha, MIP-1alpha, and RANTES in response to TLR ligands; 5) expression of cystatin C; and 6) cross-presentation of exogenous Ag to CD8 T cells. Furthermore, despite lacking surface CD8 expression, the CD24(high) subset contained CD8 mRNA and up-regulated surface expression when transferred into mice. This culture system allows access to bona fide counterparts of the splenic DC subsets.     

Differential production of IL-12, IFN-alpha, and IFN-gamma by mouse dendritic cell subsets

Dendritic cells (DC) not only stimulate T cells effectively but are also producers of cytokines that have important immune regulatory functions. In this study we have extended information on the functional differences between DC subpopulations to include differences in the production of the major immune-directing cytokines IL-12, IFN-alpha, and IFN-gamma. Splenic CD4(-)8(+) DC were identified as the major IL-12 producers in response to microbiological or T cell stimuli when compared with splenic CD4(-)8(-) or CD4(+)8(-) DC; however, all three subsets of DC showed similar IL-12 regulation and responded with increased IL-12 p70 production if IL-4 was present during stimulation. High level CD8 expression also correlated with extent of IL-12 production for DC isolated from thymus and lymph nodes. By using gene knockout mice we ruled out any role for CD8alpha itself, or of priming by T cells, on the superior IL-12-producing capacity of the CD8(+) DC. Additionally, CD8(+) DC were identified as the major producers of IFN-alpha compared with the two CD8(-) DC subsets, a finding that suggests similarity to the human plasmacytoid DC lineage. In contrast, the CD4(-)8(-) DC produced much more IFN-gamma than the CD4(-)8(+) or the CD4(+)8(-) DC under all conditions tested.     

Splenic dendritic cell subsets prime and boost CD8 T cells and are involved in the generation of effector CD8 T cells

The ability of the dendritic cell (DC) subsets, CD8alpha+ and CD8alpha- DCs, to initiate a CD8 T cell response or to activate memory CD8 T cells and generate effector CD8 T cells has been controversial. In this study, we analyse the capacity of splenic DC subsets to induce CD8 T cell responses to a CD8 T cell epitope (pb9) of a malaria antigen. The administration of peptide-pulsed CD8alpha- or CD8alpha+ DCs primes and boosts a primed CD8 T cell response against the malaria epitope. In vitro, depletion of CD11c(+) DCs from mouse splenocytes, immunised with recombinant vaccinia virus Ankara (MVA) expressing pb9 epitope, significantly reduced the generation of pb9-specific IFNgamma producing effector CD8 T cells, indicating that splenic DCs are involved in the development of pb9-specific IFNgamma producing effector cells. Taken together, this result shows that both DC subsets have the ability to prime and boost CD8 T cell responses and are involved in the activation of memory CD8 T cells.     

Induction of CTL and nonpolarized Th cell responses by CD8alpha(+) and CD8alpha(-) dendritic cells

Two distinct dendritic cell (DC) subpopulations have been evidenced in mice on the basis of their differential CD8alpha expression and their localization in lymphoid organs. Several reports suggest that CD8alpha(+) and CD8alpha(-) DC subsets could be functionally different. In this study, using a panel of MHC class I- and/or class II-restricted peptides, we analyzed CD4(+) and CD8(+) T cell responses obtained after i.v. injection of freshly purified peptide-pulsed DC subsets. First, we showed that both DC subsets efficiently induce specific CTL responses and Th1 cytokine production in the absence of CD4(+) T cell priming. Second, we showed that in vivo activation of CD4(+) T cells by CD8alpha(+) or CD8alpha(-) DC, injected i.v., leads to a nonpolarized Th response with production of both Th1 and Th2 cytokines. The CD8alpha(-) subset induced a higher production of Th2 cytokines such as IL-4 and IL-10 than the CD8alpha(+) subset. However, IL-5 was produced by CD4(+) T cells activated by both DC subsets. When both CD4(+) and CD8(+) T cells were primed by DC injected i.v., a similar pattern of cytokines was observed, but, under these conditions, Th1 cytokines were mainly produced by CD8(+) T cells, while Th2 cytokines were produced by CD4(+) T cells. Thus, this study clearly shows that CD4(+) T cell responses do not influence the development of specific CD8(+) T cell cytotoxic responses induced either by CD8alpha(+) or CD8alpha(-) DC subsets.     

Trypanosoma cruzi: flow cytometric analysis of lymphocyte subsets in susceptible and protected C3H/He mice.

Inbred strains of mice vary widely in their ability to survive infection with Trypanosoma cruzi. C3H/He mice are highly susceptible to infection with the Brazil strain T. cruzi, but can be protected by immunization with avirulent Corpus Christi strain parasites. We have examined, during the course of infection, the changes in lymphocyte populations in C3H/He mice that were infected but protected by immunization, infected but not immunized, immunized but not infected, and normal age-matched controls. Immunization- and/or infection-induced changes in lymphocyte populations in lymph nodes were unremarkable except for an increase in the percentage of Ig+ cells. Conversely, in the spleen the percentages of mu+ cells decreased and T cells increased in all manipulated animals. The increase in splenic T cell subsets in immunized only controls occurred simultaneously and thus the CD4:CD8 ratio remained similar to that of normal animals (approximately 2.2). Twenty days after infection, mice that were infected but not immunized (and thus would be expected to die 4-8 days later) showed a dramatic increase in the percentage of CD8+ cells which resulted in a decline in the CD4:CD8 ratio to 0.85. Mice protected by immunization had a CD4:CD8 ratio of 1.7 at this critical time point, which did, however, decline to 1.0 by Day 60. The percentages of all cell phenotypes examined in all mice had returned to normal levels 155 days after infection. These data suggest that alterations in the splenic CD4:CD8 ratio may be important in determining whether or not an animal can survive infection with the Brazil strain of T. cruzi.     

Relationships among murine CD11c(high) dendritic cell subsets as revealed by baseline gene expression patterns

The functional relationships and properties of different subtypes of dendritic cells (DC) remain largely undefined. To better characterize these cells, we used global gene analysis to determine gene expression patterns among murine CD11c(high) DC subsets. CD4(+), CD8alpha(+), and CD8alpha(-) CD4(-) (double negative (DN)) DC were purified from spleens of normal C57/BL6 mice and analyzed using Affymetrix microarrays. The CD4(+) and CD8alpha(+) DC subsets showed distinct basal expression profiles differing by >200 individual genes. These included known DC subset markers as well as previously unrecognized, differentially expressed CD Ags such as CD1d, CD5, CD22, and CD72. Flow cytometric analysis confirmed differential expression in nine of nine cases, thereby validating the microarray analysis. Interestingly, the microarray expression profiles for DN cells strongly resembled those of CD4(+) DC, differing from them by <25 genes. This suggests that CD4(+) and DN DC are closely related phylogenetically, whereas CD8alpha(+) DC represent a more distant lineage, supporting the historical distinction between CD8alpha(+) and CD8alpha(-) DC. However, staining patterns revealed that in contrast to CD4(+) DC, the DN subset is heterogeneous and comprises at least two subpopulations. Gene Ontology and literature mining analyses of genes expressed differentially among DC subsets indicated strong associations with immune response parameters as well as cell differentiation and signaling. Such associations offer clues to possible unique functions of the CD11c(high) DC subsets that to date have been difficult to define as rigid distinctions.     

Phenotypic and functional characterization of mouse hepatic CD8 alpha+ lymphoid-related dendritic cells

Recently, attention has focussed on phenotypic and functional differences between classic myeloid dendritic cells (DC), and DC that reportedly develop from an early, committed lymphoid precursor. In mice, DC from these separate hemopoietic lineages differ by their surface expression of CD8 alpha. We undertook a comparative study of CD8 alpha+ (CD11blow; lymphoid-related) and CD8 alpha- (CD11bhigh; myeloid) DC isolated from mouse liver. CD8 alpha+ and CD8 alpha- DC each constituted 相似文献   

Induction of protective immune responses against R5 human immunodeficiency virus type 1 (HIV-1) infection in hu-PBL-SCID mice by intrasplenic immunization with HIV-1-pulsed dendritic cells: possible involvement of a novel factor of human CD4(+) T-cell origin

The potential of a dendritic cell (DC)-based vaccine against human immunodeficiency virus type 1 (HIV-1) infection in humans was explored with SCID mice reconstituted with human peripheral blood mononuclear cells (PBMC). HIV-1-negative normal human PBMC were transplanted directly into the spleens of SCID mice (hu-PBL-SCID-spl mice) together with autologous mature DCs pulsed with either inactivated HIV-1 (strain R5 or X4) or ovalbumin (OVA), followed by a booster injection 5 days later with autologous DCs pulsed with the same respective antigens. Five days later, these mice were challenged intraperitoneally with R5 HIV-1(JR-CSF). Analysis of infection at 7 days postinfection showed that the DC-HIV-1-immunized hu-PBL-SCID-spl mice, irrespective of the HIV-1 isolate used for immunization, were protected against HIV-1 infection. In contrast, none of the DC-OVA-immunized mice were protected. Sera from the DC-HIV-1- but not the DC-OVA-immunized mice inhibited the in vitro infection of activated PBMC and macrophages with R5, but not X4, HIV-1. Upon restimulation with HIV-1 in vitro, the human CD4(+) T cells derived from the DC-HIV-1-immunized mice produced a similar R5 HIV-1 suppressor factor. Neutralizing antibodies against human RANTES, MIP-1alpha, MIP-1beta, alpha interferon (IFN-alpha), IFN-beta, IFN-gamma, interleukin-4 (IL-4), IL-10, IL-13, IL-16, MCP-1, MCP-3, tumor necrosis factor alpha (TNF-alpha), or TNF-beta failed to reverse the HIV-1-suppressive activity. These results show that inactivated HIV-1-pulsed autologous DCs can stimulate splenic resident human CD4(+) T cells in hu-PBL-SCID-spl mice to produce a yet-to-be-defined, novel soluble factor(s) with protective properties against R5 HIV-1 infection.