Inhibition Of IgE Production Research Articles

Daily intake of heat-killed Lactobacillus plantarum L-137 augments acquired immunity in healthy adults.

Heat-killed Lactobacillus plantarum strain L-137 (HK-LP) is a potent inducer of IL-12 in vitro as well as in vivo in mice. HK-LP has been shown to suppress IgE production against food allergens, as well as tumor growth in mice, through IL-12 production, which induces the T helper (Th) 1 type immune response. To determine whether the intake of HK-LP influences immune function and the quality of life (QOL), a randomized, double-blind, placebo-controlled, parallel study was conducted in healthy subjects. Sixty subjects (30 men and 30 women, mean age 56.3 y) were randomly assigned to receive a capsule containing 10 mg of HK-LP daily or a matching capsule for 12 wk. Biomarkers for innate immunity such as the natural killer activity of peripheral blood mononuclear cells, neutrophil phagocytosis, and cell surface expression of CD64 on monocytes were measured every 4 wk. Biomarkers for acquired immunity such as concanavalin A (Con A)-induced proliferation, percentages of INF-gamma and IL-4-producing cluster of differentiation (CD)4(+) T cells (Th1:Th2 ratio), and the serum IgG4:IgG ratio were measured every 4 wk or at wk 0 and wk 12. Health-related QOL was assessed using a self-rating questionnaire with 26 items. Among the measured biomarkers, the percent change in Con A-induced proliferation and the Th1:Th2 ratio in the HK-LP group was greater than those in the control group (P = 0.036 and P = 0.002, respectively). The degree of improvement in QOL was higher in the HK-LP group than in the control group at wk 8 (P = 0.049) and tended to be higher at wk 12 (P = 0.092). These results suggest that a daily intake of HK-LP augments acquired immunity, especially Th1-related immune functions in healthy subjects, thereby improving the health-related QOL.

Dendritic cells suppress IgE production in B cells

Ig class switch recombination (CSR) is triggered by the engagement of CD40 on B cells by CD40 ligand on T cells. In addition, recent studies have shown that dendritic cells (DCs) are able to directly control the CSR of B cells through B lymphocyte stimulator protein [or B cell activation factor belonging to the tumor necrosis factor family] and a proliferation-inducing ligand. We examined in this study the regulatory role of DCs in CSR and demonstrate that DCs selectively suppress IgE production from B cells stimulated by CD40 and IL-4 through two different mechanisms: by direct cell-cell interaction or by soluble factors including transforming growth factor-beta and IFN-gamma. In addition, distinct DCs utilize different mechanisms: immature bone marrow-derived dendritic cells (BMDCs) and primary lung DCs strongly inhibit IgE CSR. On the other hand, LPS-induced mature BMDCs lose the ability to inhibit IgE CSR but still suppress IgE production by decreasing IgE protein expression. These results indicate novel regulatory functions of DCs on IgE production.

Fucoidan prevents Cε germline transcription and NFκB p52 translocation for IgE production in B cells

Fucoidan, a dietary fiber contained in seaweed, reduces the increase of antigen-specific IgE in mice exposed to ovalbumin. In this study, we investigated the effect of fucoidan on IgE production and intracellular events in B cells in vitro. Fucoidan inhibited the production of IgE and Cε germline transcription in murine B cells induced by IL-4 (100 ng/ml) and anti-CD40 antibodies (10 μg/ml), whereas it stimulated cell proliferation. A significant effect of fucoidan on IgE production was observed when B cells were stimulated with a higher dose (5 μg/ml) of anti-CD40 antibodies, but not when stimulated with lower doses (1.25, 2.5 μg/ml), regardless of the IL-4 concentrations. Moreover, nuclear translocation of NFκB p52, but neither that of NFκB p65, nor the phosphorylation of JAK1 and STAT6 was reduced by fucoidan. These results suggest that fucoidan inhibited IgE production by preventing the NFκB p52-mediated pathways activated by CD40.

IgE isotype switch and IgE production are enhanced in IL-21-deficient but not IFN-γ-deficient mice in a Th2-biased response

IgE plays a critical role in the pathogenesis of allergy and asthma. Therefore, suppression of IgE production would provide therapeutic benefits to patients suffering from these diseases. We have reported that the production of IgE is regulated differently in the spleen vs. the draining lymph nodes (LN). IgE isotype switch and IgE producing B cell expansion occur in the draining LN after antigen (Ag) immunization, but do not happen in the spleen. In addition, a population of pre-existing IgE + cells is observed in the spleen of normal or sham immunized mice, but is not present in the draining LN. To further understand the regulation of IgE production in different lymphoid organs, and the potential inhibitory factors of IgE isotype switch in the spleen, the involvement of IL-21 and IFN-γ in regulating IgE production was investigated by using the IL-21 and the IFN-γ deficient mice. We found that in the absence of IL-21 IgE isotype switch and IgE + cell clonal expansion were dramatically enhanced in the spleen and IgE isotype switch was partially increased in the draining LN. In addition, IgE production of the pre-existing CD19 −CD5 +B220 low IgE + cells in the spleen was also increased in the absence of IL-21 under physiological conditions. In contrast, using the IFN-γ deficient mice, we did not observe a negative impact of IFN-γ on either IgE isotype switch or IgE production. Our data suggest that IL-21 appears to be a critical cytokine to keep low IgE levels under physiological and pathological conditions.

Intramuscular immunization with DNA construct containing Der p 2 and signal peptide sequences primed strong IgE production

Background Previous studies demonstrated that allergen gene vaccination induced TH1-skewed responses and inhibited IgE production. This study evaluated and characterized the immune responses induced by three DNA constructs encoding different forms of Der p 2 for safe and efficacious vaccination against mite allergy. Methods Mice were immunized intramuscularly with DNA constructs encoding a major mite allergen, Der p 2, without a signal peptide (p2), with a signal peptide (p52), and with a signal peptide plus lysosomal-targeting sequence (p52-LA), respectively, followed by TH2-skewed protein challenge. Antibody and T-cell cytokine responses were assessed by ELISA. Primed dendritic cells (DCs) were adoptively transferred to naïve mice and humoral responses were examined after protein challenge. The circulating Der p 2 protein was detected by sandwich ELISA. Results Mice immunized with p52-LA showed strong and clear-cut TH1-type response, as evident by high IFN-γ production and elevated levels of Der p 2-specific IgG2a production whereas construct p2 induced only moderate levels of TH1 response. In contrast, mice immunized with construct p52 showed a mixed TH1/TH2 phenotype and produced substantial circulating Der p 2 protein. Mice adoptively transferred with DCs primed by p52 construct, but not by the p2 or p52-LA constructs, were sensitized to produce high levels of Der p 2-specific IgE. Conclusions Immunization with DNA construct encoding a signal peptide could potentially prime TH2-skewed responses and IgE production. The additional inclusion of lysosomal-targeting sequences to such construct could improve the safety and efficacy of DNA vaccination against allergy.

Differential T Cell-Mediated Regulation of CD23 (FcεRII) in B Cells and Follicular Dendritic Cells

Differences in murine follicular dendritic cells (FDC)-CD23 expression under Th1 vs Th2 conditions prompted the hypothesis that T cells help regulate the phenotype of FDCs. FDCs express CD40, suggesting that T cell-CD40L and lymphokines may be involved in regulating FDC-CD23. To test this, highly enriched FDCs were incubated with CD40L trimer or anti-CD40 to mimic T cell signaling in the presence of IFN-gamma or IL-4. Surface expression of CD23 was determined by flow cytometry, whereas mRNA levels of CD23 and its isoforms CD23a and CD23b were independently measured by quantitative PCR. When FDCs were incubated with either CD40L trimer or agonistic anti-CD40 Ab, the expression of FDC-CD23 was increased both at the mRNA and protein levels. Moreover, engagement of FDC-CD40 enhanced mRNA levels for both CD23a and CD23b isoforms. In addition, IFN-gamma substantially enhanced CD23a and CD23b mRNA levels in CD40-stimulated FDCs. Curiously, IL-4 could also up-regulate FDC-CD23a but not -CD23b. Anti-IFN-gamma dramatically inhibited FDC-CD23 in mice immunized with CFA, whereas anti-IL-4 had only a modest inhibitory effect. In contrast with FDCs, IFN-gamma inhibited surface expression of murine B cell-CD23 as well as mRNA for B cell CD23a and -CD23b, whereas IL-4 dramatically enhanced message for both isoforms as well as protein expression. In short, CD23 was regulated very differently in FDCs and B cells. Previous studies suggest that high levels of FDC-CD23 inhibit IgE production, and this IFN-gamma and CD40L-mediated up-regulation of FDC-CD23 may explain, at least in part, why Th1 responses are associated with low IgE responses in vivo.

T regulatory cells in allergy: Novel concepts in the pathogenesis, prevention, and treatment of allergic diseases

The identification of T regulatory (T(Reg)) cells as key regulators of immunologic processes in peripheral tolerance to allergens has opened an important era in the prevention and treatment of allergic diseases. Both naturally occurring CD4(+)CD25(+) T(Reg) cells and inducible populations of allergen-specific IL-10-secreting T(R)1 cells inhibit allergen-specific effector cells in experimental models. Allergen-specific T(Reg) cell responses contribute to the control of allergic inflammation in several ways. Skewing of allergen-specific effector T cells to a T(Reg) phenotype appears to be a crucial event in the development of a healthy immune response to allergens and successful outcome in allergen-specific immunotherapy. The increased levels of IL-10 and TGF-beta produced by T(Reg) cells can potently suppress IgE production while simultaneously increasing the production of the noninflammatory antibody isotypes IgG4 and IgA, respectively. T(Reg) cells directly or indirectly suppress effector cells of allergic inflammation, such as mast cells, basophils, and eosinophils, and contribute to remodeling in asthma and atopic dermatitis. In addition, mediators of allergic inflammation that trigger cyclic AMP-associated G protein-coupled receptors, such as histamine receptor 2, might play a role in peripheral tolerance mechanisms against allergens. Current strategies for drug development and allergen-specific immunotherapy exploit these observations with the potential to provide cure for allergic diseases.

Are regulatory T cells the target of venom immunotherapy?

Allergen-specific immunotherapy is the only treatment that leads to lifelong tolerance to previously disease-causing allergens by restoring normal immunity against allergens. T-regulatory (TReg) cells are involved in preventing sensitization to allergens and represent a major target for venom- or other allergen-specific immunotherapy. Induction of peripheral tolerance in T cells, which is characterized mainly by suppressed proliferative and cytokine responses against the T-cell epitopes of major allergens, is an essential step in specific immunotherapy. It is initiated by the autocrine action of interleukin-10 and/or transforming growth factor-beta, which are produced by antigen-specific TReg cells. Tolerized T cells can be reactivated to produce distinct T-helper-1 or T-helper-2 cytokine patterns, thus directing allergen-specific immunotherapy toward successful or unsuccessful outcomes. TReg cells directly or indirectly influence effector cells of allergic inflammation, such as mast cells, basophils and eosinophils. In addition, there is accumulating evidence that they may suppress IgE production and induce IgG4 and IgA production against allergens. In addition, histamine released from mast cells and basophils may efficiently contribute to immunoregulation during specific immunotherapy, and affect TReg cells and the production of their cytokines via histamine receptor 2. By applying recent knowledge in TReg-cell-dependent mechanisms of peripheral tolerance, more rational and safer approaches to the prevention and cure of venom hypersensitivity may be developed in the future.

Phellinus linteus grown on germinated brown rice suppresses IgE production by the modulation of Th1/Th2 balance in murine mesenteric lymph node lymphocytes

We compared the immunomodulating effects of Phellinus linteus (PL), germinated brown rice (BR) and P. linteus grown on germinated brown rice (PB) on IgE production in murine mesenteric lymph node (MLN) lymphocytes. All extracts decreased IgE concentrations by 43--65% compared to control mice in both serum and MLN lymphocytes. In addition, PL and PB increased the proportion of CD4(+) T cells by 9% and 12% in MLN lymphocytes. IFN-gamma concentration, Th1 cytokine, was significantly increased by 44--67%, whereas IL-4 and IL-10 concentrations, Th2 cytokine, significantly decreased by 30--60% in the three treated groups compared to control group. These results suggest that PB suppresses IgE production through the modulation of Th1/Th2 balance to down-regulate Th2 response in MLN lymphocytes, even though a synergistic effect of PB was not found.

JTP-27536 [(+)-1,3-Dihydroxy-2-hydroxymethylpropyl-2-ammonium 2-[(R)-3-Cyclo-hexyl-1-phenylpropyl]-1,3-dioxo-2,3-dihydro-1H-isoindole-5-carboxylate Monohydrate], a Novel Inhibitor of Immunoglobulins and Interleukin-5 with Anti-Inflammatory Properties in Mouse Allergic Dermatitis Model

We report a novel synthetic compound JTP-27536 [(+)-1,3-dihydroxy-2-hydroxymethylpropyl-2-ammonium 2-[(R)-3-cyclohexyl-1-phenylpropyl]-1,3-dioxo-2,3-dihydro-1H-isoindole-5-carboxylate monohydrate] as an inhibitor of immunoglobulins (Igs) and interleukin (IL)-5 production in vitro and in vivo. JTP-27536 inhibited IgE production in mouse and human B cells with IC50 values of 2.5 and 2.1 microM, respectively, and the inhibition was stronger than that on IgG1 and IgM production (IC50 > 10 microM). JTP-27536 also inhibited IL-5 production in mouse splenocytes and human peripheral blood mononuclear cells with IC50 values of 3.3 and 1.3 microM, respectively, without affecting mouse interferon (IFN)-gamma, IL-2, IL-4, IL-10, or human IL-4 production. In contrast, prednisolone not only inhibited mouse IgE production but also mouse IFN-gamma, IL-2, IL-4, and IL-10 and human IL-4 and IL-5 production in vitro. The effect of suplatast tosilate, a Th2 cytokine inhibitor, on antibody and cytokine production was less potent than that of JTP-27536. In vivo animal experiments using dinitrophenylated ascaris-sensitized mice and 2,4,6-trinitro-1-chrolobenzene-induced chronic dermatitis mice showed that JTP-27536 was more potent than suplatast tosilate and comparable with prednisolone in inhibiting ear swelling, antigen-specific IgE and IL-5 production, and cell infiltrations into the inflamed tissue. These results indicate that JTP-27536 is an inhibitor of Igs, in particular IgE, and of IL-5, which has antiallergic properties in mouse dermatitis model, and suggest that an inhibitor of Igs and IL-5 like JTP-27536 may be useful as a drug for the treatment of allergic diseases.

CpG immunostimulatory sequences enhance contact hypersensitivity responses in mice.

Bacterial DNA and synthetic cytidine-phosphate-guanosine-oligodeoxynucleotides (CpG ODN) potently activate dendritic cells (DC) and therefore have been proposed as adjuvants for vaccination strategies. Although CpG ODN are considered as safe adjuvants this study shows that CpG ODN are responsible for enhanced antigen-specific skin inflammatory reactions. We used the murine model of contact hypersensitivity (CHS) to 2,4-dinitrofluorobenzene (DNFB) in which hapten-specific CD8+T cytotoxic 1 cells are effector cells. Subcutaneous injection of CpG ODN, 1 d before sensitization enhanced the CHS response to DNFB and resulted in increased recruitment of CD8+ T cells at the challenge sites, whereas control ODN injection did not have any effect. This effect was local and not systemic as it was only observed when DNFB was applied at the same site as the CpG motifs. CpG ODN-induced enhancement of CHS was due to increased antigen-presenting cell functions of DC since: (i) CpG ODN-injected skin revealed upregulated expression of major histocompatibility complex class II, CD80, and CD86 molecules and (ii) CpG ODN treatment of DNFB-derivatized DC enhanced the intensity of CHS responses after in vivo transfer. Taken together, the results show that CpG ODN may be responsible for immune side-effects such as worsening of T cell-mediated skin diseases.

Synthesis of IL-13 by human B lymphocytes: Regulation and role in IgE production

Background Our laboratory has demonstrated previously that human tonsillar B lymphocytes express IL-13 mRNA Objective We sought to investigate IL-13 production by human B cells and the association between B cell–derived IL-13 and IgE secretion. Methods Human B lymphocytes were isolated from tonsils and purified by means of rosetting with sheep RBCs or positive or negative selection with magnetic beads. They were stimulated with anti-CD40 antibodies with or without recombinant IL-4. Total mRNA was extracted, and IL-13 mRNA was measured by means of standard RT-PCR or by means of real-time PCR with commercially available primers. B cells were cultured with or without IL-13 neutralizing antibodies, and Cε transcripts and supernatant IgE levels were measured. Results IL-13 mRNA was detected in human B lymphocytes stimulated with anti-CD40 antibodies and IL-4 or IL-2 but not in unstimulated B cells. Real-time PCR demonstrated a 10- to 15-fold increase in IL-13 mRNA, maximizing at 36 hours. IL-13 protein was detected from B lymphocytes on day 3 and accumulated through day 7. The synthesis of IL-13 required both CD40 and IL-4 stimulation. The presence of IL-13 was confirmed by means of intracellular staining of cultured B lymphocytes and antigen-stimulated nasal biopsy specimens from atopic individuals. Addition of IL-13 neutralizing antibodies to purified B-cell cultures inhibited IgE production by up to 80% and diminished IgE (Cε) transcripts by 50%. Conclusion Human B lymphocytes express IL-13 mRNA after ligation of CD40 and the addition of cytokines. Human B lymphocytes produce significant IL-13, and neutralization of IL-13 impairs IgE synthesis. IL-13 might be an important autocrine growth factor for IgE-producing B lymphocytes.

Suppression of IgE production and modulation of Th1/Th2 cell response by electroacupuncture in DNP-KLH immunized mice

Effects of electroacupuncture (EA) on Th1/Th2 cell response were investigated in BALB/c mice immunized intraperitoneally with 2,4-dinitrophenylated keyhole limpet protein (DNP-KLH). Successive electroacupuncture stimulation on the ST36 acupoint was performed just after immunization. Serum levels of antigen-specific IgE and total IgE were significantly decreased compared with non-acupunctured controls. Production of the Th2-specific cytokines IL-4 and IL-13 in the anti-CD3 mAb-activated splenocytes was significantly suppressed in ST36 electroacupunctured mice compared with non-acupunctured mice. These results imply that successive electroacupuncture on ST36 can decrease the serum level of antigen-specific IgE and total IgE by suppression of the Th2 lineage development.

ＩｇＥ抗体誘発皮膚炎モデル動物および卵白アルブミン経口投与後の血中ＩｇＥ濃度に及ぼすにがりの作用

The effect of bittern on a mouse IgE-mediated dermatitis model was examined. Both the immediate- and delayed-type responses elicited by the IgE-antigen treatment were significantly suppressed in mice treated with bittern. On the other hand, MgCl2, the main component of bittern, failed to suppress either the immediate-or delayed-type response. Furthermore, bittern was found to inhibit IgE production in mice treated with ovalbumin. These results suggest that bittern may improve the pathological state of human atopic dermatitis.

Inhibition of T helper 2-type responses, IgE production and eosinophilia by synthetic lipopeptides.

In allergy and asthma, the fine balance between the T helper (Th) 1, Th2 and T regulatory cytokine responses appears to be shifted towards Th2. Here, we report that synthetic lipopeptides which contain the typical lipid part of the lipoprotein of gram-negative bacteria stimulate a distinct regulatory cytokine pattern and inhibit several Th2 cell-related phenomena. The most potent analogue of synthetic lipopeptides, lipopeptide CGP 40774 (LP40) was not active in MyD88-deficient mice and stimulated Toll-like receptor (TLR)-2, but not TLR-4. LP40 potentiated the production of IFN-gamma and IL-10, but not IL-4 and IL-5 by human T cells. In addition, triggering of TLR-2 by lipopeptides promoted the in vitro differentiation of naive T cells towards IL-10- and IFN-gamma-producing T cells and suppressed IL-4 production by Th2 cells. Accordingly, LP40 inhibited IgE production induced by allergen, anti-IgD antibody, Nippostrongylus brasiliensis or murine acquired immunodeficiency virus. Furthermore, ovalbumin-induced lung eosinophilic inflammation was abolished and Schistosoma mansoni egg-induced granuloma size and eosinophil counts were suppressed in mice by LP40. These results demonstrate that stimulation of TLR-2 by lipopeptides represents a novel way for possible treatment of allergy and asthma by regulating the disrupted cytokine balance.

Suppression of allergic reactions by dehulled adlay in association with the balance of TH1/TH2 cell responses.

Dehulled adlay is known as a natural Chinese medicine having antiallergic activity, although its mechanism remains unclear. This study examined the effects of dehulled adlay on antigen-specific antibody and cytokine production. Mice were immunized three times with ovalbumin (OVA) in alum adjuvant. It was found that oral administration of dehulled adlay in mice suppressed the production of IgE against OVA antigen. Serum anti-OVA IgG(2a) antibody levels were significantly increased in mice after oral administration of dehulled adlay. Furthermore, the production of IL-2 by OVA-stimulated splenocytes was augmented in dehulled adlay-fed mice. Although dehulled adlay had no effect on the serum anti-OVA IgG(1) antibody levels, it had a great capacity to reduce IL-5 secretion by means of OVA-stimulated splenocytes. Hydrothermal processes, including steaming and extrusion cooking, did not change the capacity of dehulled adlay to suppress IgE production. Three fractions of dehulled alday, including methanolic extract, warm water extract, and residue, were obtained. The methanolic extract exhibited the greatest capacity to reduce anti-OVA IgE production. These results suggest that dehulled adlay has a modulating ability to shift the balance from Th2 to Th1 dominance in the T cell mediated immune system and may be beneficial for the treatment of allergic disorders.

1?,25-dihydroxyvitamin?D3 inhibits anti-CD40 plus IL-4-mediated IgE productionin vitro

In the present study, we examined whether anti-CD40+IL-4-mediated B cell proliferation and immunoglobulin synthesis is affected by vitamin D (VD) and its low-hypercalcemic analogue EB1089 in Bcells from healthy donors. Analysis of vitamin D receptor (VDR) expression showed that only anti-CD40+IL-4-stimulated, but not resting B cells express VDR. Studies on B cell proliferation revealed that anti-CD40+IL-4-mediated proliferation of B cells was not affected by VD or EB1089. By contrast, IgE synthesis was markedly inhibited by both, VD and EB1089, starting at concentrations from 10(-10) M for VD and 10(-12) M for EB1089, with maximal inhibition at 10(-6) M (VD 85.5+/-9.7%; EB1089 77.3+/-10.8%). The production of the other Ig (IgA and IgG) was not significantly inhibited by VD after anti-CD40+IL-4 stimulation, and IgM production was only slightly reduced (18.7+/-7.9%). These observations were confirmed by intracellular staining of the different isotypes in B cells after anti-CD40+IL-4 stimulation, which showed a strong reduction of IgE(+) cells in the presence of VD. Analyses of molecules that are known to affect IgE production (CD23 and IL-6) revealed that these are not involved in VD-dependent inhibition of IgE production. By contrast, epsilon germ-line transcription was inhibited by VD (41.2+/-26.1%; n=5), as was NF-kappaB (p50 and p65) protein expression in stimulated cells. These data show that VD and its analogue EB1089 inhibit IgE production of anti-CD40+IL-4-stimulated B cells in vitro. The involved mechanism includes epsilon germ-line transcription, NF-kappaB activation and switch recombination suggesting that complex mechanisms of VD action in anti-CD40+IL-4-stimulated B cells are responsible.

1alpha,25-dihydroxyvitamin D3 inhibits anti-CD40 plus IL-4-mediated IgE production in vitro.

In the present study, we examined whether anti-CD40+IL-4-mediated B cell proliferation and immunoglobulin synthesis is affected by vitamin D (VD) and its low-hypercalcemic analogue EB1089 in Bcells from healthy donors. Analysis of vitamin D receptor (VDR) expression showed that only anti-CD40+IL-4-stimulated, but not resting B cells express VDR. Studies on B cell proliferation revealed that anti-CD40+IL-4-mediated proliferation of B cells was not affected by VD or EB1089. By contrast, IgE synthesis was markedly inhibited by both, VD and EB1089, starting at concentrations from 10(-10) M for VD and 10(-12) M for EB1089, with maximal inhibition at 10(-6) M (VD 85.5+/-9.7%; EB1089 77.3+/-10.8%). The production of the other Ig (IgA and IgG) was not significantly inhibited by VD after anti-CD40+IL-4 stimulation, and IgM production was only slightly reduced (18.7+/-7.9%). These observations were confirmed by intracellular staining of the different isotypes in B cells after anti-CD40+IL-4 stimulation, which showed a strong reduction of IgE(+) cells in the presence of VD. Analyses of molecules that are known to affect IgE production (CD23 and IL-6) revealed that these are not involved in VD-dependent inhibition of IgE production. By contrast, epsilon germ-line transcription was inhibited by VD (41.2+/-26.1%; n=5), as was NF-kappaB (p50 and p65) protein expression in stimulated cells. These data show that VD and its analogue EB1089 inhibit IgE production of anti-CD40+IL-4-stimulated B cells in vitro. The involved mechanism includes epsilon germ-line transcription, NF-kappaB activation and switch recombination suggesting that complex mechanisms of VD action in anti-CD40+IL-4-stimulated B cells are responsible.

Inhibition of IgE Production by the Imidazoquinoline Resiquimod in Nonallergic and Allergic Donors

The aim of this study was to examine whether the immune modulator resiquimod, which belongs like imiquimod to the imidazoquinolines, is capable of influencing IgE synthesis. Peripheral blood mono-nuclear cells from normal donors and patients with atopic dermatitis and with seasonal allergic rhinitis were analyzed in the presence of resiquimod, anti-CD40+interleukin-4 stimulation for induction of IgE, and anti-CD40+interleukin-4 in the presence of resiquimod, respectively. Our data show that spontaneous IgE production was inhibited in the presence of resiquimod, which was strongest at 10 ng per ml in both groups of allergic patients. Inhibition of IgE production after anti-CD40+interleukin-4 stimulation in the presence of resiquimod (10 ng per ml) was comparable between all the groups. In normal donors median inhibition of IgE synthesis was 93%, in seasonal allergic rhinitis patients 77%, and in patients with atopic dermatitis 72%. In order to rule out antiproliferative effects of resiquimod, which might influence IgE production, we also studied proliferation of peripheral blood mononuclear cells from normal donors, which remained unchanged in the presence of resiquimod at 0.1-10 ng per ml but was inhibited at 100 or 1000 ng per ml. In search of possible mechanisms responsible for the observed inhibition of IgE production, we analyzed the expression and production of molecules that are known to modulate IgE production, namely CD23 and interferon-gamma. CD23 expression on B cells was lower in the presence of resiquimod (10 ng per ml) in anti-CD40+interleukin-4 stimulated cells, whereas interferon-gamma was strongly induced (4-6-fold) by resiquimod (10 ng per ml). Furthermore, by using neutralizing interferon-gamma monoclonal antibodies, we show that inhibition of IgE production occurred in an interferon-gamma-dependent manner. Taken together our results show that resiquimod is a potent modulator of IgE production in vitro in normal but also in allergic donors.

Prolongation of heart allograft survival of rats treated by a Th2 inhibitor

In terms of Th1/Th2 balance in response to signals given during donor antigen presentation, induction of tolerance is more often correlated with Th2-type than with Th1-type reactions. However, in our study, heart allograft survival was prolonged by treatment of rats with a Th2 inhibitor. Suplatast tosilate (IPD; Taiho; Tokyo, Japan) is a novel immunoregulator that suppresses IgE production and eosinophil infiltration through selective inhibition of interleukin (IL)-4 and IL-5 synthesis by Th2-like cells but not IFN-γ production in Th1 cells. Five LEW rats of DA heart grafts were treated with IPD (100 μg/day, p.o.) for 10 days. Heart allograft survival of all IPD-treated cases was prolonged more than 14 days while the beating of heart grafts in control groups was stopped within 9 days. In an in vitro study, the cell proliferation both in Con A blast and in mixed lymphocyte reaction assay was suppressed by IPD in dose-dependent manner. We could at least in part conclude that Th2 inhibition might temporarily suppress heart allograft rejection.