Suppression Of Delayed-type Hypersensitivity Research Articles

Orally Administered Exosomes Suppress Mouse Delayed-Type Hypersensitivity by Delivering miRNA-150 to Antigen-Primed Macrophage APC Targeted by Exosome-Surface Anti-Peptide Antibody Light Chains.

We previously discovered suppressor T cell-derived, antigen (Ag)-specific exosomes inhibiting mouse hapten-induced contact sensitivity effector T cells by targeting antigen-presenting cells (APCs). These suppressive exosomes acted Ag-specifically due to a coating of antibody free light chains (FLC) from Ag-activated B1a cells. Current studies are aimed at determining if similar immune tolerance could be induced in cutaneous delayed-type hypersensitivity (DTH) to the protein Ag (ovalbumin, OVA). Intravenous administration of a high dose of OVA-coupled, syngeneic erythrocytes similarly induced CD3+CD8+ suppressor T cells producing suppressive, miRNA-150-carrying exosomes, also coated with B1a cell-derived, OVA-specific FLC. Simultaneously, OVA-immunized B1a cells produced an exosome subpopulation, originally coated with Ag-specific FLC, that could be rendered suppressive by in vitro association with miRNA-150. Importantly, miRNA-150-carrying exosomes from both suppressor T cells and B1a cells efficiently induced prolonged DTH suppression after single systemic administration into actively immunized mice, with the strongest effect observed after oral treatment. Current studies also showed that OVA-specific FLC on suppressive exosomes bind OVA peptides suggesting that exosome-coating FLC target APCs by binding to peptide-Ag-major histocompatibility complexes. This renders APCs capable of inhibiting DTH effector T cells. Thus, our studies describe a novel immune tolerance mechanism mediated by FLC-coated, Ag-specific, miRNA-150-carrying exosomes that act on the APC and are particularly effective after oral administration.

Early IFNγ-Mediated and Late Perforin-Mediated Suppression of Pathogenic CD4 T Cell Responses Are Both Required for Inhibition of Demyelinating Disease by CNS-Specific Autoregulatory CD8 T Cells.

Pathogenesis of immune-mediated demyelinating diseases like multiple sclerosis (MS) is thought to be governed by a complex cellular interplay between immunopathogenic and immunoregulatory responses. We have previously shown that central nervous system (CNS)-specific CD8 T cells have an unexpected protective role in the mouse model of MS, experimental autoimmune encephalomyelitis (EAE). In this study, we interrogated the suppressive potential of PLP178-191-specific CD8 T cells (PLP-CD8). Here, we show that PLP-CD8, when administered post-disease onset, rapidly ameliorated EAE progression, and suppressed PLP178-191-specific CD4 T cell responses as measured by delayed-type hypersensitivity (DTH). To accomplish DTH suppression, PLP-CD8 required differential production of perforin and IFNγ. Perforin was not required for the rapid suppressive action of these cells, but was critical for maintenance of optimal longer term DTH suppression. Conversely, IFNγ production by PLP-CD8 was necessary for swift DTH suppression, but was less significant for maintenance of longer term suppression. These data indicate that CNS-specific CD8 T cells employ an ordered regulatory mechanism program over a number of days in vivo during demyelinating disease and have mechanistic implications for this immunotherapeutic approach.

Neuroantigen-specific CD8 T cells inhibit ongoing demyelinating disease by autoregulating CD4 T cell responses using temporally distinct IFNγ- and perforin-dependent mechanisms.

Abstract Pathogenesis of immune-mediated demyelinating diseases like multiple sclerosis (MS) is thought to be governed by a complex cellular interplay between immunopathological and immunoregulatory responses. We have previously shown that neuroantigen-specific CD8 T cells have an unexpected protective role in the mouse model of MS, experimental autoimmune encephalomyelitis (EAE). In this study, we interrogated the immunotherapeutic potential of PLP178–191-specific CD8 T cells. Here, we show that PLP178–191-specific CD8 T cells, when administered post-disease onset, swiftly ameliorated EAE progression and suppressed PLP178–191-specific CD4 T cell responses as measured by delayed-type hypersensitivity (DTH). To accomplish DTH suppression, PLP178–191-specific CD8 T cells required differential production of perforin and IFNγ. Perforin was ancillary for the rapid suppressive action of PLP178–191-specific CD8 T cells, but was necessary for maintenance of optimal longer term DTH suppression. Conversely, IFNγ production by PLP178–191-specific CD8 T cells was necessary for swift DTH suppression, but was less significant for maintenance of longer term suppression. These data indicate that neuroantigen-specific CD8 T cells employ an ordered regulatory mechanism program over a number of days in vivo during demyelinating disease and have mechanistic implications for this immunotherapeutic approach.

Pretreatment antigen-specific immunity and regulation - association with subsequent immune response to anti-tumor DNA vaccination

BackgroundImmunotherapies have demonstrated clinical benefit for many types of cancers, however many patients do not respond, and treatment-related adverse effects can be severe. Hence many efforts are underway to identify treatment predictive biomarkers. We have reported the results of two phase I trials using a DNA vaccine encoding prostatic acid phosphatase (PAP) in patients with biochemically recurrent prostate cancer. In both trials, persistent PAP-specific Th1 immunity developed in some patients, and this was associated with favorable changes in serum PSA kinetics. In the current study, we sought to determine if measures of antigen-specific or antigen non-specific immunity were present prior to treatment, and associated with subsequent immune response, to identify possible predictive immune biomarkers.MethodsPatients who developed persistent PAP-specific, IFNγ-secreting immune responses were defined as immune “responders.” The frequency of peripheral T cell and B cell lymphocytes, natural killer cells, monocytes, dendritic cells, myeloid derived suppressor cells, and regulatory T cells were assessed by flow cytometry and clinical laboratory values. PAP-specific immune responses were evaluated by cytokine secretion in vitro, and by antigen-specific suppression of delayed-type hypersensitivity to a recall antigen in an in vivo SCID mouse model.ResultsThe frequency of peripheral blood cell types did not differ between the immune responder and non-responder groups. Non-responder patients tended to have higher PAP-specific IL-10 production pre-vaccination (p = 0.09). Responder patients had greater preexisting PAP-specific bystander regulatory responses that suppressed DTH to a recall antigen (p = 0.016).ConclusionsWhile our study population was small (n = 38), these results suggest that different measures of antigen-specific tolerance or regulation might help predict immunological outcome from DNA vaccination. These will be prospectively evaluated in an ongoing randomized, phase II trial.

Serotonin signalling is crucial in the induction of PUVA-induced systemic suppression of delayed-type hypersensitivity but not local apoptosis or inflammation of the skin.

Psoralen and UVA (PUVA) has immunosuppressive and proapoptotic effects, which are thought to be responsible alone or in combination for its therapeutic efficacy. However, the molecular mechanism by which PUVA mediates its effects is not well understood. Activation of the serotonin (5-hydroxytryptamine, 5-HT) pathway has been suggested to be involved in the modulation of T-cell responses and found to mediate UVB-induced immune suppression. In particular, the activation of the 5-HT2A receptor has been proposed as one mechanism responsible for UV-induced immune suppression. We therefore hypothesized that 5-HT may play a role in PUVA-induced effects. The model of systemic suppression of delayed-type hypersensitivity (DTH) to Candida albicans was used to study immune function after exposure of C3H and KIT(W) (-Sh/W-Sh) mice to a minimal inflammatory dose of topical PUVA. The intra-peritoneal injection of the 5-HT2 receptor antagonist ketanserin or cyproheptadine or an anti-5-HT antibody immediately before PUVA exposure entirely abrogated suppression of DTH but had no significant effect on inflammation, as measured by swelling and cellular infiltration of the skin, and apoptosis as determined by the number of sunburn cells in C3H mice. Importantly, the systemic injection of 5-HT recapitulated PUVA immune suppression of DTH but did not induce inflammation or apoptosis in the skin. KIT(W) (-Sh/W-Sh) mice (exhibiting myelopoietic abnormalities, including lack of 5-HT-containing mast cells) were resistant to PUVA-induced suppression of DTH but not local skin swelling. Thus, this points towards a crucial role of 5-HT signalling in PUVA-induced immune suppression but not inflammation or apoptosis insitu in the skin.

Ag and IL‐2 immune complexes efficiently expand Ag‐specific Treg cells that migrate in response to chemokines and reduce localized immune responses

An intravenous administration of a high-dose antigen (Ag) can induce immune tolerance and suppress the immune response, but the mechanism remains unclear. We recently proved that a combined i.v. administration of OVA and IL-2-anti-IL-2 Ab immune complexes (IL-2 ICs) efficiently expands OVA-specific Treg cells in the thymus and induces their migration into peripheral blood, by using OVA-specific TCR Tg-expressing DO11.10 mice. Here, we demonstrate that the expanded OVA-specific Treg cells rapidly move into the air pouch after OVA injection in DO11.10 mice. The migration was inhibited by blocking the axis of a chemokine receptor, CCR2. Moreover, prior treatment with OVA and IL-2 ICs enhanced OVA-specific Treg-cell migration and inhibited OVA-induced delayed-type hypersensitivity (DTH) reactions in the skin of BM chimeric mice with 15% of T cells expressing OVA-specific TCR. Blocking the CCR2 axis reversed this suppression of DTH in these mice. Furthermore, prior treatment with OVA and IL-2 ICs effectively reduced DTH reactions even in WT mice possessing only a very small population of OVA-specific T cells. Thus, the treatment with Ag and IL-2 ICs can efficiently expand Ag-specific Treg cells with the capacity to migrate and reduce localized immune responses.

Eye‐Mediated Induction of Specific Immune Tolerance to Encephalitogenic Antigens

Administration of antigens into the anterior chamber (AC) of the eye induces a form of antigen-specific immune tolerance termed anterior chamber-associated immune deviation (ACAID). This immune tolerance effectively impairs host delayed-type hypersensitivity (DTH) responses. We hypothesized that ACAID could be generated in BALB/c mice following AC inoculation of the encephalitogenic antigens myelin oligodendrocyte glycoprotein (MOG) and myelin basic protein (MBP). We used DTH assays and local adoptive transfer (LAT) assays to test whether MOG/MBP-induced ACAID following their administration into the AC, whether they elicited this immune tolerance via CD8(+) T cells, and whether their AC coadministration (MOG/MBP) induced specific immune tolerance to one or both antigens. We showed that MOG/MBP-induced AC-mediated specific immune tolerance, as evident from impaired DTH responses. This antigen-driven DTH suppression was solely mediated via splenic CD8(+) T cells as confirmed by LAT assays. Finally, a single AC injection with both antigens was sufficient to induce specific immune tolerance to these antigens, as evident from DTH and LAT assays. ACAID T-cell regulation could be used as a therapeutic tool in the treatment of complicated autoimmune diseases that involve multiple antigens such as multiple sclerosis.

Modulation of cellular immunity by antibodies against calreticulin

Although caltreticulin (CRT) is mainly a residential ER protein, it is also expressed on the membrane surface of various types of cells exhibiting multiple functions. We report here that intraperitoneal administration of a soluble recombinant CRT fragment (rCRT/39-272) led to a substantial decrease in delayed type hypersensitivity (DTH) responses in BALB/c mice and EAE in C57BL/6 mice. In the recall response against keyhole limpet hemocyanin (KLH) in vitro, draining lymph node cells from the rCRT/39-272-treated mice produced less IFN-γ but more IL-4 as compared with the cells from the control group. The immunomodulating effect of intraperitoneally administered rCRT/39-272 was attributed to anti-CRT Abs thereby induced, because, in passive transfer experiments, the CRT-specific antiserum could suppress DTH in BALB/c mice. B-cell-deficient μMT mice were not susceptible to rCRT/39-272-mediated DTH suppression. Furthermore, CRT appears on the surface of murine T cells soon after activation and remains detectable (at relatively low level) by flow cytometry for approximately 5 days in vitro. Anti-CRT Abs were able to inhibit AKT phosphorylation, proliferation, and cytokine production by activated murine T cells. We propose that cell surface CRT could play a role in the function of effector T cells and may be considered a target for immunological manipulation.

Inhibition of delayed-type hypersensitivity by iron oxide nanoparticle administration is predominantly via suppressing T helper 1 cell-mediated immunity

Inhibition of delayed-type hypersensitivity by iron oxide nanoparticle administration is predominantly via suppressing T helper 1 cell-mediated immunity

Immune Amplification of Murine CD8+ Suppressor T Cells Induced via An Immune-Privileged Site: Quantifying Suppressor T Cells Functionally

BackgroundCD8+ suppressor T cells exert antigen-specific suppression of the expression of hypersensitivity by activated T cells. Therefore, CD8+ suppressor T cells serve a major regulatory role for the control of active immunity. Accordingly, the number and/or activity of CD8+ suppressor T cells should be influenced by an immune response to the antigen. To test this hypothesis we used an adoptive transfer assay that measures the suppression of the expression of delayed-type hypersensitivity (DTH) by CD8+ suppressor T cells to quantify the antigen-specific suppression of DTH by these suppressor T cells.MethodsSuppressor T cells were induced in the spleens of mice by the injection of antigen into the anterior chamber of an eye. Following this injection, the mice were immunized by the same antigen injected into the anterior chamber. Spleen cells recovered from these mice (AC-SPL cells) were titrated in an adoptive transfer assay to determine the number of AC-SPL cells required to effect a 50% reduction of antigen-induced swelling (Sw50) in the footpad of immunized mice challenged by antigen.ResultsSuppression of the expression of DTH is proportional to the number of AC-SPL cells injected into the site challenged by antigen. The number of AC-SPL cells required for a 50% reduction in DTH-induced swelling is reduced by injecting a cell population enriched for CD8+ AC-SPL cells. Immunizing the mice receiving intracameral antigen to the same antigen decreases the RSw50 of AC-SPL cells required to inhibit the expression of DTH.ConclusionsThe results provide the first quantitative demonstration that the numbers of antigen-specific splenic CD8+ suppressor T cells are specifically amplified by antigen during an immune response.

Tumor-Derived Exosomes Confer Antigen-Specific Immunosuppression in a Murine Delayed-Type Hypersensitivity Model

Exosomes are endosome-derived small membrane vesicles that are secreted by most cell types including tumor cells. Tumor-derived exosomes usually contain tumor antigens and have been used as a source of tumor antigens to stimulate anti-tumor immune responses. However, many reports also suggest that tumor-derived exosomes can facilitate tumor immune evasion through different mechanisms, most of which are antigen-independent. In the present study we used a mouse model of delayed-type hypersensitivity (DTH) and demonstrated that local administration of tumor-derived exosomes carrying the model antigen chicken ovalbumin (OVA) resulted in the suppression of DTH response in an antigen-specific manner. Analysis of exosome trafficking demonstrated that following local injection, tumor-derived exosomes were internalized by CD11c+ cells and transported to the draining LN. Exosome-mediated DTH suppression is associated with increased mRNA levels of TGF-β1 and IL-4 in the draining LN. The tumor-derived exosomes examined were also found to inhibit DC maturation. Taken together, our results suggest a role for tumor-derived exosomes in inducing tumor antigen-specific immunosuppression, possibly by modulating the function of APCs.

Systemic Low-Dose UVB Inhibits CD8 T Cells and Skin Inflammation by Alternative and Novel Mechanisms

Exposure to UVB radiation before antigen delivery at an unirradiated site inhibits functional immunological responses. Mice treated dorsally with suberythemal low-dose UVB and immunized with ova in abdominal skin generated ova-specific CD8 T cells with a significantly decreased activation, expansion, and cytotoxic activity compared with unirradiated mice. UVB also impaired the delayed-type hypersensitivity (DTH) reaction to ova. Transfer of CD4⁺CD25⁺cells from UVB-exposed mice did not suppress the ova-specific CD8 T-cell response or DTH reaction in unexposed mice, confirming that systemic low-dose UVB does not induce long-lived functional regulatory CD4⁺CD25⁺ T cells. Repairing cyclobutane pyrimidine dimer-type DNA damage and blocking aryl hydrocarbon receptor signaling also did not reverse the immunosuppressive effect of UVB on ova-specific CD8 T cells and DTH, suggesting that cyclobutane pyrimidine dimers and the aryl hydrocarbon receptor are not required in systemic low-dose UVB-induced immunosuppression. The known UVB chromophore, cis-urocanic acid, and reactive oxygen species triggered the inhibition of DTH caused by UVB, but they were not involved in the modulation of CD8 T cells. These findings indicate that systemic low-dose UVB impedes the primary response of antigen-specific CD8 T cells by a novel mechanism that is independent of pathways known to be involved in systemic suppression of DTH.

Ein Januskopf?

Interferon alpha (IFN-α) and interferon beta (IFN-β) are naturally occurring cytokines, which belong to the type I interferons and share the same receptor leading to very similar therapeutic effects. The immunomodulatory effect of type I interferons includes modulation of antibody production, inhibition of lymphocyte proliferation, inhibition of delayed-type hypersensitivity and enhancement of T-cell and NK-cell cytotoxicity. An increasing number of open clinical studies and case reports have demonstrated the efficacy of IFN-α for severe ocular inflammation in patients with Behçet's disease and of interferon-β, which has been used mainly for the treatment of multiple sclerosis.

Sepsis-induced apoptosis leads to active suppression of delayed-type hypersensitivity by CD8+ regulatory T cells through a TRAIL-dependent mechanism.

Patients who survive severe sepsis often display severely compromised immune function. One hallmark of such immune suppression in septic patients is an impaired delayed-type hypersensitivity (DTH) response, manifested by a loss of skin testing to recall Ags. Because sepsis induces significant apoptosis in lymphoid and myeloid cells, and apoptotic cells are themselves tolerogenic, we tested the hypothesis that suppression of DTH is mediated by tolerogenic properties of the apoptotic cells generated during sepsis. Mice subjected to cecal ligation and puncture demonstrated a loss of DTH for the 7 d following cecal ligation and puncture; however, the immune response returned to normal by day 10. Blocking sepsis-induced apoptosis via Bcl-2 overexpression or Bim deficiency prevented the loss of DTH. Importantly, injection of apoptotic cells into Bim-/- mice prevented an effective DTH response, thereby suggesting a causal link between apoptotic cells and immune suppression. Surprisingly, when TRAIL null mice were examined, we found that these animals had significant apoptosis but retained their DTH responses. Further studies revealed that apoptotic cells generated during sepsis induced a CD8+ regulatory T cell that suppressed DTH by TRAIL production. These results establish a link between apoptotic cells and immune suppression during sepsis and suggest TRAIL may be a viable therapeutic target for boosting the adaptive immune response following sepsis.

Sepsis-induced immunosuppression is mediated by TRAIL-expressing CD8+ regulatory T cells (87.13)

Abstract Patients who survive severe sepsis often display severely compromised immune function. One hallmark of such immune suppression in septic patients is an impaired delayed-type hypersensitivity (DTH) response, manifested by a loss of skin testing to recall antigens. Since sepsis induces significant apoptosis in lymphoid and myeloid cells and apoptotic cells are themselves tolerogenic, we tested the hypothesis that suppression of DTH is mediated by tolerogenic properties of the apoptotic cells generated during sepsis. Mice subjected to cecal ligation and puncture (CLP) demonstrated a loss of DTH for the 7 days following CLP; however, the immune response returned to normal by day 10. Blocking sepsis-induced apoptosis via Bcl-2 overexpression or Bim deficiency prevented the loss of DTH. Importantly, injection of apoptotic cells into Bim-/- mice prevented an effective DTH response, thereby suggesting a causal link between apoptotic cells and immune suppression. Surprisingly, when Trail-/- mice were examined, we found that these animals had significant apoptosis but retained their DTH responses. Further studies revealed that apoptotic cells generated during sepsis induced a CD8+ regulatory T cell (Treg) that mediated suppressed DTH by TRAIL production. These results establish a link between apoptotic cells and immune suppression during sepsis, and suggest TRAIL may be a viable therapeutic target for boosting the adaptive immune response following sepsis.

Hypersensitivity and oral tolerance in the absence of a secretory immune system

Mucosal immunity protects the epithelial barrier by immune exclusion of foreign antigens and by anti-inflammatory tolerance mechanisms, but there is a continuing debate about the role of secretory immunoglobulins (SIgs), particularly SIgA, in the protection against allergy and other inflammatory diseases. Lack of secretory antibodies may cause immune dysfunction and affect mucosally induced (oral) tolerance against food antigens. We used polymeric Ig receptor (pIgR) knockout (KO) mice, which cannot export SIgA or SIgM, to study oral tolerance induction by ovalbumin (OVA) feeding and for parenteral antigen sensitization in the same animal. Remarkable systemic hyperreactivity was observed in pIgR KO mice, as 50% died after intradermal OVA challenge, which was not seen in similarly sensitized and challenged wild-type (WT) mice. Oral tolerance induced by OVA completely protected the sensitized pIgR KO mice against anaphylaxis and suppressed antibody levels (particularly IgG1) as well as delayed-type hypersensitivity (DTH) to OVA. Delayed-type hypersensitivity to a bystander antigen, human serum albumin, was also suppressed and T-cell proliferation against OVA in vitro was reduced in tolerized compared with non-tolerized pIgR KO mice. This effect was largely mediated by CD25+ T cells. Adoptive transfer of splenic putative regulatory T cells (CD4+ CD25+) obtained from OVA-fed pIgR KO mice to naïve WT mice mediated suppression of DTH against OVA after sensitization of the recipients. Compensatory regulatory T-cell function becomes critical in pIgR-deficient mice to avoid the potentially catastrophic effects of systemic immune hyperreactivity, presumably resulting from defective secretory antibody-mediated immune exclusion of microbial components.

Inhibition of Delayed-Type Hypersensitivity by Cucurbitacin R through the Curbing of Lymphocyte Proliferation and Cytokine Expression by Means of Nuclear Factor AT Translocation to the Nucleus

Cucurbitacin R is known to exhibit an anti-inflammatory effect in different experimental models of inflammation. In this article, we outline the effect of cucurbitacin R on T lymphocyte proliferation, cytokine production, and nuclear factor activation, as well as its influence on various experimental models of delayed-type hypersensitivity (DTH) in mice. Cucurbitacin R reduced the proliferation of phytohemagglutinin A-stimulated human T lymphocytes (IC(50), 18 microM), modifying the cell cycle, as well as the production of cytokines [interleukin (IL)-2, IL-4, IL-10, and especially interferon-gamma] and the induction of the principal cyclins implicated in the cell cycle (A(1), B(1), D(2), and E). These effects are brought on by a novel, selective inhibition of nuclear factor AT (NFAT) by cucurbitacin R, with no concomitant effect on other transcription factors such as activator protein-1. In addition, we tested the in vivo effects of cucurbitacin R in three experimental models of DTH, as well as its effects on T lymphocyte proliferation, the cell cycle, cytokines, and cyclins. Although cucurbitacin R was found to reduce the inflammatory response brought on by both oxazolone and dinitrofluorobenzene, its activity was even more pronounced against sheep red blood cell-induced edema in mouse paws, with a clear reduction in the production of IL-1beta, IL-4, and tumor necrosis factor alpha in the inflamed paw. In conclusion, cucurbitacin R has the potential to be a new immunosuppressive agent with antiproliferative effects through the inhibition of the NFAT with anti-inflammatory activity in DTH reactions.

T cell sensitivity to TGF- is required for the effector function but not the generation of splenic CD8+ regulatory T cells induced via the injection of antigen into the anterior chamber

The introduction of antigen into the anterior chamber (AC) of the eye induces the production of antigen-specific splenic CD8+ regulatory T cells (AC-SPL cells) that suppress a delayed-type hypersensitivity (DTH) reaction in immunized mice. Because the generation of these regulatory T cells is also induced by exposure to transforming growth factor (TGF)-β and antigen or F4/80+ cells exposed to TGF-β and antigen in vitro, we investigated (i) whether these cells are produced in dominant negative receptor for transforming growth factor β receptor type II (dnTGFβRII) or Cbl-b−/− mice whose T cells are resistant to TGF-β, (ii) whether DTH is suppressed by wild type (WT) CD8+ AC-SPL cells in Cbl-b−/− and dnTGFβRII mice and (iii) the effect of antibodies to TGF-β on the suppression of DTH by CD8+ AC-SPL cells. DnTGFβRII immunized and Cbl-b−/− mice produced splenic CD8+ regulatory cells after the intracameral injection of antigen and immunization. The suppression of a DTH reaction by CD8+ AC-SPL cells in WT mice was blocked by the local inclusion of antibodies to TGF-β when WT splenic CD8+ AC-SPL cells were injected into the DTH reaction site. Moreover, the DTH reaction in immunized dnTGFβRII and Cbl-b−/− mice was not suppressed by the transfer of WT CD8+ AC-SPL cells to the site challenged with antigen. In aggregate, these observations suggest that T cell sensitivity to TGF-β is not an obligate requirement for the in vivo induction of CD8+ AC-SPL T cells but the suppression of an in vivo DTH reaction by CD8+ AC-SPL cells is dependent on TGF-β.

Induction of regulatory dendritic cells by topical application of NF-κB decoy oligodeoxynucleotides

Dendritic cells (DC) have a key role in inducing an immune response, but DC in different maturation states are responsible for inducing tolerance. Topical application of nuclear factor (NF)-κB decoy oligodeoxynucleotides (ODN) induces antigen-specific peripheral tolerance in delayed-type hypersensitivity (DTH) to ovalbumin (OVA) by expanding CD4 +CD25 + regulatory T cells and by inhibiting DC migration. Herein we describe how topical NF-κB decoy ODN modulate DC maturation with respect to their migration, phenotype, and cytokine profiles. Topical application of NF-κB decoy ODN after OVA sensitization delayed the migration of Langerhans cells (LC) into draining lymph nodes, and morphologically mature LC remained in the peripheral tissue 2 days longer than in OVA-sensitized mice without application of NF-κB decoy ODN. During migration, NF-κB decoy-treated DC preferentially expressed inhibitory B7 molecules (i.e., B7-H1, B7-DC, and B7-H3) compared to OVA-sensitized DC without NF-κB decoy ODN, whereas co-stimulatory molecules (MHC class II, B7-1 and B7-2) were upregulated. Adoptive transfer of NF-κB decoy-treated DC inhibited DTH induction in prophylactic and therapeutic experiments. Inhibition of DTH by DC transfer was antigen-specific in vivo. This decoy ODN strategy might be useful for regulating immunity through DC.

Immunomodulatory Activities of Kolaviron, a Mixture of Three Related Biflavonoids of Garcinia kola Heckel

The immunomodulatory properties of kolaviron (KV), a mixture of three related biflavonoids of Garcinia kola Heckel (Clusiaceae), were investigated. The study was conducted using in vitro and in vivo immunocompetent and immunocompromised animal models. KV (250 and 500 mg/kg) produced a dose-dependent and significant (p < 0.05) inhibition of delayed-type hypersensitivity in rats and also caused a significant (p < 0.05) increase in the primary and secondary sheep erythrocytes-specific antibody titres in rats. In vitro, KV inhibited the classical complement system at concentrations greater than 100 μg/ml. The administration of KV ameliorated the cyclophosphamide-induced leukopenia and increased the proportion of lymphocytes count in rats after 14 days of treatment. Administration of KV on alternate days after immunosuppression with cyclophospamide increased the rate of excision wound closure and reduced epithelialization period from 21.75 to 15.5 days. This study established the immunomodulatory and immunorestorative properties of KV, which could be harnessed for possible clinical benefits to immunodeficient patients.