InVivoMAb anti-mouse CD86 (B7-2)

Catalog #BE0025
Product Citations:
12
Clone:
GL-1
Reactivities:
Mouse

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Product Details

The GL-1 monoclonal antibody reacts with mouse CD86 also known as B7-2. CD86 is an 80 kDa Ig superfamily member. CD86 is expressed by activated T and B cells, macrophages, and dendritic cells. This ligand binds to CD28 to provide a costimulatory signal necessary for T cell activation and survival, and cytokine production. Additionally, CD80 binds to CTLA-4 which inhibits T cells. This antibody has been shown to block CD86 in vivo and inhibit the priming of cytotoxic T cells.

Specifications

Isotype Rat IgG2a, κ
Recommended Isotype Control(s) InVivoMAb rat IgG2a isotype control, anti-trinitrophenol
Recommended Dilution Buffer InVivoPure pH 7.0 Dilution Buffer
Conjugation This product is unconjugated. Conjugation is available via our Antibody Conjugation Services.
Immunogen LPS-activated CBA/Ca mouse splenic B cells
Reported Applications in vivo CD86 blockade
Flow cytometry
Formulation PBS, pH 7.0
Contains no stabilizers or preservatives
Endotoxin <2EU/mg (<0.002EU/μg)
Determined by LAL gel clotting assay
Purity >95%
Determined by SDS-PAGE
Sterility 0.2 µm filtration
Production Purified from cell culture supernatant in an animal-free facility
Purification Protein G
RRID AB_1107678
Molecular Weight 150 kDa
Storage The antibody solution should be stored at the stock concentration at 4°C. Do not freeze.
In vivo CD86 blockade
Marshall, D., et al. (2014). "Differential requirement for IL-2 and IL-15 during bifurcated development of thymic regulatory T cells" J Immunol 193(11): 5525-5533. PubMed

The developmental pathways of regulatory T cells (T(reg)) generation in the thymus are not fully understood. In this study, we reconstituted thymic development of Zap70-deficient thymocytes with a tetracycline-inducible Zap70 transgene to allow temporal dissection of T(reg) development. We find that T(reg) develop with distinctive kinetics, first appearing by day 4 among CD4 single-positive (SP) thymocytes. Accepted models of CD25(+)Foxp3(+) T(reg) selection suggest development via CD25(+)Foxp3(-) CD4 SP precursors. In contrast, our kinetic analysis revealed the presence of abundant CD25(-)Foxp3(+) cells that are highly efficient at maturing to CD25(+)Foxp3(+) cells in response to IL-2. CD25(-)Foxp3(+) cells more closely resembled mature T(reg) both with respect to kinetics of development and avidity for self-peptide MHC. These population also exhibited distinct requirements for cytokines during their development. CD25(-)Foxp3(+) cells were IL-15 dependent, whereas generation of CD25(+)Foxp3(+) specifically required IL-2. Finally, we found that IL-2 and IL-15 arose from distinct sources in vivo. IL-15 was of stromal origin, whereas IL-2 was of exclusively from hemopoetic cells that depended on intact CD4 lineage development but not either Ag-experienced or NKT cells.

In vivo CD86 blockade, Flow Cytometry
Moser, E. K., et al. (2014). "Late engagement of CD86 after influenza virus clearance promotes recovery in a FoxP3+ regulatory T cell dependent manner" PLoS Pathog 10(8): e1004315. PubMed

Influenza A virus (IAV) infection in the respiratory tract triggers robust innate and adaptive immune responses, resulting in both virus clearance and lung inflammation and injury. After virus clearance, resolution of ongoing inflammation and tissue repair occur during a distinct recovery period. B7 family co-stimulatory molecules such as CD80 and CD86 have important roles in modulating T cell activity during the initiation and effector stages of the host response to IAV infection, but their potential role during recovery and resolution of inflammation is unknown. We found that antibody-mediated CD86 blockade in vivo after virus clearance led to a delay in recovery, characterized by increased numbers of lung neutrophils and inflammatory cytokines in airways and lung interstitium, but no change in conventional IAV-specific T cell responses. However, CD86 blockade led to decreased numbers of FoxP3+ regulatory T cells (Tregs), and adoptive transfer of Tregs into alphaCD86 treated mice rescued the effect of the blockade, supporting a role for Tregs in promoting recovery after virus clearance. Specific depletion of Tregs late after infection mimicked the CD86 blockade phenotype, confirming a role for Tregs during recovery after virus clearance. Furthermore, we identified neutrophils as a target of Treg suppression since neutrophil depletion in Treg-depleted mice reduced excess inflammatory cytokines in the airways. These results demonstrate that Tregs, in a CD86 dependent mechanism, contribute to the resolution of disease after IAV infection, in part by suppressing neutrophil-driven cytokine release into the airways.

In vivo CD86 blockade
Srivastava, S., et al. (2014). "Type I interferons directly inhibit regulatory T cells to allow optimal antiviral T cell responses during acute LCMV infection" J Exp Med 211(5): 961-974. PubMed

Regulatory T (T reg) cells play an essential role in preventing autoimmunity but can also impair clearance of foreign pathogens. Paradoxically, signals known to promote T reg cell function are abundant during infection and could inappropriately enhance T reg cell activity. How T reg cell function is restrained during infection to allow the generation of effective antiviral responses remains largely unclear. We demonstrate that the potent antiviral type I interferons (IFNs) directly inhibit co-stimulation-dependent T reg cell activation and proliferation, both in vitro and in vivo during acute infection with lymphocytic choriomeningitis virus (LCMV). Loss of the type I IFN receptor specifically in T reg cells results in functional impairment of virus-specific CD8(+) and CD4(+) T cells and inefficient viral clearance. Together, these data demonstrate that inhibition of T reg cells by IFNs is necessary for the generation of optimal antiviral T cell responses during acute LCMV infection.

In vivo CD86 blockade
Arjunaraja, S., et al. (2012). "Structurally identical capsular polysaccharide expressed by intact group B streptococcus versus Streptococcus pneumoniae elicits distinct murine polysaccharide-specific IgG responses in vivo" J Immunol 188(11): 5238-5246. PubMed

We previously reported distinct differences in the murine in vivo Ig polysaccharide (PS)-specific responses to intact Streptococcus pneumoniae compared with responses to Neisseria meningitidis and that in each case, the bacterial subcapsular domain markedly influences the Ig response to the associated PS. In light of potentially unique contributions of biochemically distinct capsular PS and/or their characteristic attachments to the underlying bacterium, it remains unresolved whether different bacterial subcapsular domains can exert differential effects on PS-specific Ig responses to distinct bacterial pathogens. In this report, we used a mutant strain of group B Streptococcus (Streptococcus agalactiae) type III (GBS-III) that expresses desialylated capsular polysaccharide of GBS-III, biochemically identical to capsular pneumococcal polysaccharide type 14 (PPS14) of Streptococcus pneumoniae (intact inactivated Streptococcus pneumoniae, capsular type 14, Pn14), directly to compare the in vivo PPS14-specific IgG responses to two distinct gram-positive bacteria. Although both GBS-III and Pn14 elicited relatively rapid primary PPS14-specific IgG responses dependent on CD4(+) T cells, B7-dependent costimulation, and CD40-CD40L interactions, only GBS-III induced a highly boosted ICOS-dependent PPS14-specific IgG response after secondary immunization. Of note, priming with Pn14 and boosting with GBS-III, although not isolated PPS14, elicited a similar boosted PPS14-specific IgG response that was dependent on CD4(+) T cells during secondary immunization, indicating that Pn14 primes for memory but, unlike GBS-III, fails to elicit it. The inability of Pn14 to elicit a boosted PPS14-specific IgG response was overcome by coimmunization with unencapsulated GBS-III. Collectively, these data establish that structurally identical capsular PS expressed by two distinct gram-positive extracellular bacteria can indeed elicit distinct PS-specific IgG responses in vivo.

In vivo CD86 blockade
Kastenmuller, W., et al. (2011). "Regulatory T cells selectively control CD8+ T cell effector pool size via IL-2 restriction" J Immunol 187(6): 3186-3197. PubMed

Regulatory T cells (Treg) are key players in maintaining immune homeostasis but have also been shown to regulate immune responses against infectious pathogens. Therefore, Treg are a promising target for modulating immune responses to vaccines to improve their efficacy. Using a viral vector system, we found that Treg act on the developing immune response early postinfection by reducing the extent of dendritic cell costimulatory molecule expression. Due to this change and the lower IL-2 production that results, a substantial fraction of CD8(+) effector T cells lose CD25 expression several days after activation. Surprisingly, such Treg-dependent limitations in IL-2 signaling by Ag-activated CD8(+) T cells prevent effector differentiation without interfering with memory cell formation. In this way, Treg fine-tune the numbers of effector T cells generated while preserving the capacity for a rapid recall response upon pathogen re-exposure. This selective effect of Treg on a subpopulation of CD8(+) T cells indicates that although manipulation of the Treg compartment might not be optimal for prophylactic vaccinations, it can be potentially exploited to optimize vaccine efficacy for therapeutic interventions.

    • Cancer Research
    • ,
    • Mus musculus (House mouse)
    EMT activates exocytotic Rabs to coordinate invasion and immunosuppression in lung cancer.

    In Proceedings of the National Academy of Sciences of the United States of America on 11 July 2023 by Xiao, G. Y., Tan, X., et al.

    PubMed

    Epithelial-to-mesenchymal transition (EMT) underlies immunosuppression, drug resistance, and metastasis in epithelial malignancies. However, the way in which EMT orchestrates disparate biological processes remains unclear. Here, we identify an EMT-activated vesicular trafficking network that coordinates promigratory focal adhesion dynamics with an immunosuppressive secretory program in lung adenocarcinoma (LUAD). The EMT-activating transcription factor ZEB1 drives exocytotic vesicular trafficking by relieving Rab6A, Rab8A, and guanine nucleotide exchange factors from miR-148a-dependent silencing, thereby facilitating MMP14-dependent focal adhesion turnover in LUAD cells and autotaxin-mediated CD8+ T cell exhaustion, indicating that cell-intrinsic and extrinsic processes are linked through a microRNA that coordinates vesicular trafficking networks. Blockade of ZEB1-dependent secretion reactivates antitumor immunity and negates resistance to PD-L1 immune checkpoint blockade, an important clinical problem in LUAD. Thus, EMT activates exocytotic Rabs to drive a secretory program that promotes invasion and immunosuppression in LUAD.

    • Mus musculus (House mouse)
    • ,
    • Immunology and Microbiology
    Mouse T cell priming is enhanced by maturation-dependent stiffening of the dendritic cell cortex.

    In eLife on 27 July 2020 by Blumenthal, D., Chandra, V., et al.

    PubMed

    T cell activation by dendritic cells (DCs) involves forces exerted by the T cell actin cytoskeleton, which are opposed by the cortical cytoskeleton of the interacting antigen-presenting cell. During an immune response, DCs undergo a maturation process that optimizes their ability to efficiently prime naïve T cells. Using atomic force microscopy, we find that during maturation, DC cortical stiffness increases via a process that involves actin polymerization. Using stimulatory hydrogels and DCs expressing mutant cytoskeletal proteins, we find that increasing stiffness lowers the agonist dose needed for T cell activation. CD4+ T cells exhibit much more profound stiffness dependency than CD8+ T cells. Finally, stiffness responses are most robust when T cells are stimulated with pMHC rather than anti-CD3ε, consistent with a mechanosensing mechanism involving receptor deformation. Taken together, our data reveal that maturation-associated cytoskeletal changes alter the biophysical properties of DCs, providing mechanical cues that costimulate T cell activation. © 2020, Blumenthal et al.

    • Mus musculus (House mouse)
    • ,
    • Immunology and Microbiology
    The E3 ubiquitin ligase MARCH1 regulates antimalaria immunity through interferon signaling and T cell activation.

    In Proceedings of the National Academy of Sciences of the United States of America on 14 July 2020 by Wu, J., Xia, L., et al.

    PubMed

    Malaria infection induces complex and diverse immune responses. To elucidate the mechanisms underlying host-parasite interaction, we performed a genetic screen during early (24 h) Plasmodium yoelii infection in mice and identified a large number of interacting host and parasite genes/loci after transspecies expression quantitative trait locus (Ts-eQTL) analysis. We next investigated a host E3 ubiquitin ligase gene (March1) that was clustered with interferon (IFN)-stimulated genes (ISGs) based on the similarity of the genome-wide pattern of logarithm of the odds (LOD) scores (GPLS). March1 inhibits MAVS/STING/TRIF-induced type I IFN (IFN-I) signaling in vitro and in vivo. However, in malaria-infected hosts, deficiency of March1 reduces IFN-I production by activating inhibitors such as SOCS1, USP18, and TRIM24 and by altering immune cell populations. March1 deficiency increases CD86+DC (dendritic cell) populations and levels of IFN-γ and interleukin 10 (IL-10) at day 4 post infection, leading to improved host survival. T cell depletion reduces IFN-γ level and reverse the protective effects of March1 deficiency, which can also be achieved by antibody neutralization of IFN-γ. This study reveals functions of MARCH1 (membrane-associated ring-CH-type finger 1) in innate immune responses and provides potential avenues for activating antimalaria immunity and enhancing vaccine efficacy.

    • Mus musculus (House mouse)
    • ,
    • Immunology and Microbiology
    T cell priming is enhanced by maturation-dependent stiffening of the dendritic cell cortex

    Preprint on BioRxiv : the Preprint Server for Biology on 23 June 2019 by Blumenthal, D., Avery, L., et al.

    PubMed

    h4>ABSTRACT/h4> T cell activation by dendritic cells (DCs) involves forces exerted by the T cell actin cytoskeleton, which are opposed by the cortical cytoskeleton of the interacting APC. During an immune response, DCs undergo a maturation process that optimizes their ability to efficiently prime naïve T cells. Using atomic force microscopy, we find that during maturation, DC cortical stiffness increases via process that involves actin polymerization. Using stimulatory hydrogels and DCs expressing mutant cytoskeletal proteins, we find that increasing stiffness lowers the agonist dose needed for T cell activation. CD4 + T cells exhibit much more profound stiffness-dependency than CD8 + T cells. Finally, stiffness responses are most robust when T cells are stimulated with pMHC rather than anti-CD3ε, consistent with a mechanosensing mechanism involving receptor deformation. Taken together, our data reveal that maturation-associated cytoskeletal changes alter the biophysical properties of DCs, providing mechanical cues that costimulate T cell activation.

    • Block
    • ,
    • Mus musculus (House mouse)
    • ,
    • Immunology and Microbiology
    Unregulated antigen-presenting cell activation by T cells breaks self tolerance.

    In Proceedings of the National Academy of Sciences of the United States of America on 15 January 2019 by Yi, J., Jung, J., et al.

    PubMed

    T cells proliferate vigorously following acute depletion of CD4+ Foxp3+ T regulatory cells [natural Tregs (nTregs)] and also when naive T cells are transferred to syngeneic, nTreg-deficient Rag1-/- hosts. Here, using mice raised in an antigen-free (AF) environment, we show that proliferation in these two situations is directed to self ligands rather than food or commensal antigens. In both situations, the absence of nTregs elevates B7 expression on host dendritic cells (DCs) and enables a small subset of naive CD4 T cells with high self affinity to respond overtly to host DCs: bidirectional T/DC interaction ensues, leading to progressive DC activation and reciprocal strong proliferation of T cells accompanied by peripheral Treg (pTreg) formation. Likewise, high-affinity CD4 T cells proliferate vigorously and form pTregs when cultured with autologous DCs in vitro in the absence of nTregs: this anti-self response is MHCII/peptide dependent and elicited by the raised level of B7 on cultured DCs. The data support a model in which self tolerance is imposed via modulation of CD28 signaling and explains the pathological effects of superagonistic CD28 antibodies.

    • Biochemistry and Molecular biology
    • ,
    • Mus musculus (House mouse)
    Low-Protein Diet Induces IRE1α-Dependent Anticancer Immunosurveillance.

    In Cell Metabolism on 3 April 2018 by Rubio-Patiño, C., Bossowski, J. P., et al.

    PubMed

    Dietary restriction (DR) was shown to impact on tumor growth with very variable effects depending on the cancer type. However, how DR limits cancer progression remains largely unknown. Here, we demonstrate that feeding mice a low-protein (Low PROT) isocaloric diet but not a low-carbohydrate (Low CHO) diet reduced tumor growth in three independent mouse cancer models. Surprisingly, this effect relies on anticancer immunosurveillance, as depleting CD8+ T cells, antigen-presenting cells (APCs), or using immunodeficient mice prevented the beneficial effect of the diet. Mechanistically, we established that a Low PROT diet induces the unfolded protein response (UPR) in tumor cells through the activation of IRE1α and RIG1 signaling, thereby resulting in cytokine production and mounting an efficient anticancer immune response. Collectively, our data suggest that a Low PROT diet induces an IRE1α-dependent UPR in cancer cells, enhancing a CD8-mediated T cell response against tumors. Copyright © 2018 Elsevier Inc. All rights reserved.

    • Mus musculus (House mouse)
    • ,
    • Cardiovascular biology
    • ,
    • Immunology and Microbiology
    Pulmonary Dendritic Cell Subsets Shape the Respiratory Syncytial Virus-Specific CD8+ T Cell Immunodominance Hierarchy in Neonates.

    In The Journal of Immunology on 1 January 2017 by Malloy, A. M., Ruckwardt, T. J., et al.

    PubMed

    Young infants are generally more susceptible to viral infections and experience more severe disease than do adults. CD8+ T cells are important for viral clearance, and although often ineffective in neonates they can be protective when adequately stimulated. Using a murine CB6F1/J hybrid model of respiratory syncytial virus (RSV) infection, we previously demonstrated that the CD8+ T cell immunodominance hierarchy to two RSV-derived epitopes, KdM282-90 and DbM187-195, was determined by the age at infection. To determine whether age-dependent RSV-specific CD8+ T cell responses could be modified through enhanced innate signaling, we used TLR4 or TLR9 agonist treatment at the time of infection, which remarkably changed the neonatal codominant response to an adult-like KdM282-90 CD8+ T cell immunodominant response. This shift was associated with an increase in the number of conventional dendritic cells, CD11b+ and CD103+ dendritic cells, in the lung-draining lymph node, as well as increased expression of the costimulatory molecule CD86. The magnitude of the KdM282-90 CD8+ T cell response in TLR agonist-treated neonates could be blocked with Abs against CD80 and CD86. These studies demonstrate the age-dependent function of conventional dendritic cells, their role in determining immunodominance hierarchy, and epitope-specific CD8+ T cell requirements for costimulation, all of which influence the immune response magnitude. The unique impact of TLR agonists on neonatal T cell responses is important to consider for RSV vaccines designed for young infants.

    • Immunology and Microbiology
    Late engagement of CD86 after influenza virus clearance promotes recovery in a FoxP3+ regulatory T cell dependent manner.

    In PLoS Pathogens on 1 August 2014 by Moser, E. K., Hufford, M. M., et al.

    PubMed

    Influenza A virus (IAV) infection in the respiratory tract triggers robust innate and adaptive immune responses, resulting in both virus clearance and lung inflammation and injury. After virus clearance, resolution of ongoing inflammation and tissue repair occur during a distinct recovery period. B7 family co-stimulatory molecules such as CD80 and CD86 have important roles in modulating T cell activity during the initiation and effector stages of the host response to IAV infection, but their potential role during recovery and resolution of inflammation is unknown. We found that antibody-mediated CD86 blockade in vivo after virus clearance led to a delay in recovery, characterized by increased numbers of lung neutrophils and inflammatory cytokines in airways and lung interstitium, but no change in conventional IAV-specific T cell responses. However, CD86 blockade led to decreased numbers of FoxP3+ regulatory T cells (Tregs), and adoptive transfer of Tregs into αCD86 treated mice rescued the effect of the blockade, supporting a role for Tregs in promoting recovery after virus clearance. Specific depletion of Tregs late after infection mimicked the CD86 blockade phenotype, confirming a role for Tregs during recovery after virus clearance. Furthermore, we identified neutrophils as a target of Treg suppression since neutrophil depletion in Treg-depleted mice reduced excess inflammatory cytokines in the airways. These results demonstrate that Tregs, in a CD86 dependent mechanism, contribute to the resolution of disease after IAV infection, in part by suppressing neutrophil-driven cytokine release into the airways.

    • Immunology and Microbiology
    Quantitative and qualitative deficits in neonatal lung-migratory dendritic cells impact the generation of the CD8+ T cell response.

    In PLoS Pathogens on 1 February 2014 by Ruckwardt, T. J., Malloy, A. M., et al.

    PubMed

    CD103+ and CD11b+ populations of CD11c+MHCIIhi murine dendritic cells (DCs) have been shown to carry antigens from the lung through the afferent lymphatics to mediastinal lymph nodes (MLN). We compared the responses of these two DC populations in neonatal and adult mice following intranasal infection with respiratory syncytial virus. The response in neonates was dominated by functionally-limited CD103+ DCs, while CD11b+ DCs were diminished in both number and function compared to adults. Infecting mice at intervals through the first three weeks of life revealed an evolution in DC phenotype and function during early life. Using TCR transgenic T cells with two different specificities to measure the ability of CD103+ DC to induce epitope-specific CD8+ T cell responses, we found that neonatal CD103+ DCs stimulate proliferation in a pattern distinct from adult CD103+ DCs. Blocking CD28-mediated costimulatory signals during adult infection demonstrated that signals from this costimulatory pathway influence the hierarchy of the CD8+ T cell response to RSV, suggesting that limited costimulation provided by neonatal CD103+ DCs is one mechanism whereby neonates generate a distinct CD8+ T cell response from that of adults.

    • Immunology and Microbiology
    Resolution of experimental lung injury by monocyte-derived inducible nitric oxide synthase.

    In The Journal of Immunology on 1 September 2012 by D'Alessio, F. R., Tsushima, K., et al.

    PubMed

    Although early events in the pathogenesis of acute lung injury (ALI) have been defined, little is known about the mechanisms mediating resolution. To search for determinants of resolution, we exposed wild type (WT) mice to intratracheal LPS and assessed the response at intervals to day 10, when injury had resolved. Inducible NO synthase (iNOS) was significantly upregulated in the lung at day 4 after LPS. When iNOS-/- mice were exposed to intratracheal LPS, early lung injury was attenuated; however, recovery was markedly impaired compared with WT mice. iNOS-/- mice had increased mortality and sustained increases in markers of lung injury. Adoptive transfer of WT (iNOS+/+) bone marrow-derived monocytes or direct adenoviral gene delivery of iNOS into injured iNOS-/- mice restored resolution of ALI. Irradiated bone marrow chimeras confirmed the protective effects of myeloid-derived iNOS but not of epithelial iNOS. Alveolar macrophages exhibited sustained expression of cosignaling molecule CD86 in iNOS-/- mice compared with WT mice. Ab-mediated blockade of CD86 in iNOS-/- mice improved survival and enhanced resolution of lung inflammation. Our findings show that monocyte-derived iNOS plays a pivotal role in mediating resolution of ALI by modulating lung immune responses, thus facilitating clearance of alveolar inflammation and promoting lung repair.

    • Immunology and Microbiology
    Abrogation of CD40-CD154 signaling impedes the homeostasis of thymic resident regulatory T cells by altering the levels of IL-2, but does not affect regulatory T cell development.

    In The Journal of Immunology on 15 August 2012 by Cuss, S. M. & Green, E. A.

    PubMed

    Identification of costimulatory signals required for murine regulatory T (Treg) cell development relies on measuring the frequency of total thymic Treg cells. However, the thymus contains both resident and newly developed Treg cells; whether such signals target both populations is unknown. In this study, we show that CD40-CD154 blockade specifically targeted thymic resident Treg cells, but not, as was previously believed, newly developed Treg cells. Unlike CD28-CD80/CD86 signals, CD40-CD154 signals were not required for Treg cell precursor development. Instead we demonstrate that homeostatic proliferation of thymic resident Treg cells was dependent on CD40-CD154 signals maintaining IL-2 levels. Furthermore, in newborn mice, where all Treg cells are newly developed, blockade of CD40-CD154 signals had no effect on thymic Treg numbers or their proliferation. Our studies highlight the complexity in the study of thymic Treg cell development due to the heterogeneity of thymic Treg cells.

    • Immunology and Microbiology
    Structurally identical capsular polysaccharide expressed by intact group B streptococcus versus Streptococcus pneumoniae elicits distinct murine polysaccharide-specific IgG responses in vivo.

    In The Journal of Immunology on 1 June 2012 by Arjunaraja, S., Paoletti, L. C., et al.

    PubMed

    We previously reported distinct differences in the murine in vivo Ig polysaccharide (PS)-specific responses to intact Streptococcus pneumoniae compared with responses to Neisseria meningitidis and that in each case, the bacterial subcapsular domain markedly influences the Ig response to the associated PS. In light of potentially unique contributions of biochemically distinct capsular PS and/or their characteristic attachments to the underlying bacterium, it remains unresolved whether different bacterial subcapsular domains can exert differential effects on PS-specific Ig responses to distinct bacterial pathogens. In this report, we used a mutant strain of group B Streptococcus (Streptococcus agalactiae) type III (GBS-III) that expresses desialylated capsular polysaccharide of GBS-III, biochemically identical to capsular pneumococcal polysaccharide type 14 (PPS14) of Streptococcus pneumoniae (intact inactivated Streptococcus pneumoniae, capsular type 14, Pn14), directly to compare the in vivo PPS14-specific IgG responses to two distinct gram-positive bacteria. Although both GBS-III and Pn14 elicited relatively rapid primary PPS14-specific IgG responses dependent on CD4(+) T cells, B7-dependent costimulation, and CD40-CD40L interactions, only GBS-III induced a highly boosted ICOS-dependent PPS14-specific IgG response after secondary immunization. Of note, priming with Pn14 and boosting with GBS-III, although not isolated PPS14, elicited a similar boosted PPS14-specific IgG response that was dependent on CD4(+) T cells during secondary immunization, indicating that Pn14 primes for memory but, unlike GBS-III, fails to elicit it. The inability of Pn14 to elicit a boosted PPS14-specific IgG response was overcome by coimmunization with unencapsulated GBS-III. Collectively, these data establish that structurally identical capsular PS expressed by two distinct gram-positive extracellular bacteria can indeed elicit distinct PS-specific IgG responses in vivo.

    • Immunology and Microbiology
    Regulatory T cells selectively control CD8+ T cell effector pool size via IL-2 restriction.

    In The Journal of Immunology on 15 September 2011 by Kastenmüller, W., Gasteiger, G., et al.

    PubMed

    Regulatory T cells (Treg) are key players in maintaining immune homeostasis but have also been shown to regulate immune responses against infectious pathogens. Therefore, Treg are a promising target for modulating immune responses to vaccines to improve their efficacy. Using a viral vector system, we found that Treg act on the developing immune response early postinfection by reducing the extent of dendritic cell costimulatory molecule expression. Due to this change and the lower IL-2 production that results, a substantial fraction of CD8(+) effector T cells lose CD25 expression several days after activation. Surprisingly, such Treg-dependent limitations in IL-2 signaling by Ag-activated CD8(+) T cells prevent effector differentiation without interfering with memory cell formation. In this way, Treg fine-tune the numbers of effector T cells generated while preserving the capacity for a rapid recall response upon pathogen re-exposure. This selective effect of Treg on a subpopulation of CD8(+) T cells indicates that although manipulation of the Treg compartment might not be optimal for prophylactic vaccinations, it can be potentially exploited to optimize vaccine efficacy for therapeutic interventions.