Suppression of murine IgE responses with amino acid polymer/allergen conjugates. V. By intranasal administration

Serum IgE antibody responses were generated in mice by intranasal exposure to grass pollen extract. Primary IgE responses were suppressed by the concomitant intranasal administration of a conjugate of polysarcosine and pollen extract which has been shown to be a potent tolerogen when given parenterally. Partial suppression of boosted IgE responses was observed when the conjugate was applied intranasally with a secondary challenge of unmodified extract. The data suggest that clinical schedules of intranasal application of tolerogenic conjugates can be devised to bring about specific IgE suppression.     

Characterization of the Mouse and Rat IgE Antibody Responses to Timothy Pollen by Means of Crossed Radioimmunoelectrophoresis

The IgE antibody responses to timothy pollen allergens in one rat strain and five mouse strains were investigated by means of crossed radioimmunoelectrophoresis. The rodent strains were selected for their capacity to respond with IgE antibody production. When sensitized parenterally with the antigen mixed in alum, the animals produced IgE antibodies to essentially the same antigens in timothy pollen as timothy sensitive patients have been shown to do. Thus, the allergenicity of the complex mixture of antigens in a timothy extract is similarly expressed in animals immunized parenterally with alum as in patients sensitized by inhalation.     

Induction of antibody responses to new B cell epitopes indicates vaccination character of allergen immunotherapy.

Whether the modulation of antibody responses can contribute to the improvement of clinical symptoms in patients receiving allergen immunotherapy represents a controversial issue. We have used purified [seven recombinant (r) and one natural] timothy grass pollen allergens as well as recombinant B cell epitope-containing fragments of the major timothy grass pollen allergen, Phl p 1, to investigate humoral immune responses in eight allergic patients receiving grass pollen-specific immunotherapy. We found that the administration of aluminium hydroxide-adsorbed grass pollen extract induced complex changes in allergen/epitope-specific antibody responses: increases in IgG subclass (IgG1, IgG2, IgG4) responses against allergens recognized before the therapy were observed. All eight patients started to mount IgE and IgG4 responses to continuous Phl p 1 epitopes not recognized before the therapy and a de novo induction of IgE antibodies against new allergens was found in one patient. Evidence for a protective role of IgG antibodies specific for continuous Phl p 1 epitopes was provided by the demonstration that preincubation of rPhl p 1 with human serum containing therapy-induced Phl p 1-specific IgG inhibited rPhl p 1-induced histamine release from basophils of a grass pollen-allergic patient. Our finding that immunotherapy induced antibody responses against previously not recognized B cell epitopes indicates the vaccination character of this treatment. The fact that patients started to mount de novo IgE as well as protective IgG responses against epitopes may explain the unpredictability of specific immunotherapy performed with allergen extracts and emphasizes the need for novel forms of component-resolved immunotherapy.     

The role of major olive pollen allergens Ole e 1, Ole e 9, and Ole e 10 on mice sensitization.

BACKGROUND: Olive pollen is an important cause of allergy in Mediterranean countries. To date, 10 allergens (Ole e 1 to Ole e 10) have been isolated and characterized. Animal models of olive pollen allergy are suitable tools for testing the efficacy and safety of new forms of immunotherapy. OBJECTIVES: To characterize the immune response in mice sensitized with olive pollen extract and to compare it with that of allergic patients. METHODS: BALB/c mice were sensitized by 4 intraperitoneal injections of olive pollen extract in aluminum hydroxide. The allergic state was proved by measuring serum specific IgG1 and total IgE antibody levels. The IgG1 responses to olive pollen allergens were assayed by immunoblotting and enzyme-linked immunosorbent assay. Competition experiments between human IgE and mouse IgG1 binding to olive pollen allergens were performed. RESULTS: Sensitization with olive pollen extract induced high levels of specific IgG1 and total IgE in all tested animals. Immunoblotting experiments showed that the mouse IgG1 binding pattern to pollen extract was complex and heterogeneous, as occurs with human IgE. High IgG1 antibody levels to the major olive pollen allergens described for humans were detected in serum samples from sensitized mice, whereas minor olive pollen allergens induced no significant IgG1 response. Coincubation of mouse serum samples with a cocktail of Ole e 1, Ole e 9, and Ole e 10 resulted in a significant decrease (60%) in IgG1 binding to olive pollen extract. Specific mouse IgG1 strongly inhibited human IgE binding to olive pollen allergens. CONCLUSIONS: This mouse model of olive pollen sensitization mimics immunologic features of human pollinosis and could be a useful tool for designing novel forms of immunotherapy for olive pollen allergy based on allergen cocktails.     

Basophil histamine release in patients with hay fever. Results compared with specific IgE and total IgE during immunotherapy.

Histamine release from leucocytes was demonstrated in grass pollen hay fever patients on in vitro challenge with extract of Pleum pratense (timothy). No release was found in persons without a history of grass pollen allergy. During preseasonal hyposensitization the following tendencies were found in cell sensitivity to allergen as well as in specific IgE antibody level of serum: an initial increase at the beginning of the therapy followed by a decrease during the pollen season. This is in contrast to untreated hay fever patients in whom an increase or no change at all of cell sensitivity and specific IgE was observed in the pollen season. Immunotherapy, therefore, can prevent such an increase in the pollen season. The mechanism might be due to a depression of the IgE production. In untreated as well as in treated patients the cell sensitivity was found to be significantly correlated to the grass specific IgE determined by RAST but not to the total serum level of IgE estimated by RIST. It seems likely that the sensitivity would be useful for evaluating the degree of allergy in grass pollen hay fever patients treated or not treated with immunotherapy.     

Measurement of the absolute levels of IgE antibodies in patients with ragweed hay fever: Effect of immunotherapy on seasonal changes and relationship to IgG antibodies

The effect of immunotherapy with aqueous ragweed pollen extract on changes in IgE antibody was analyzed in 40 untreated patients with ragweed hay fever and compared to changes in 63 treated patients. Treated patients received cumulative doses prior to and during treatment ranging from 1.4 × 10⁵ to 4.8 × 10⁶ protein nitrogen units (PNU). IgG antibody to ragweed antigen E (AgE) was measured by radioimmunoprecipitation, while IgE antibody to allergens in crude ragweed extract was measured by the radioallergosorbent test (RAST). The RAST procedure was calibrated using a serum whose content of IgE antibody in nanograms per milliliter had been determined by immunoabsorption, and with this method the absolute quantities of IgE antibodies to ragweed allergens could be measured. Control experiments indicated that the IgG antibodies in the sera of the treated patients did not interfere with the measurements of IgE antibodies. The levels of IgE antibody in serum varied from less than 5 ng/ml to approximately 3,000 ng/ml. IgE antibodies decreased from October, 1973, to July, 1974, and rose sharply from July to October, 1974, following the pollination season. In both untreated and treated patient groups the magnitudes of the decreases were related (p < 0.001) to the levels of IgE antibody in October, and the magnitudes of the rises were related to the levels of IgE antibody in July. In the treated patients with IgE antibody less than 71 ng/ml in October, the rate of decrease (October to July) was less than in the untreated patients. Comparison of the rises in IgE antibody from July to October revealed that these were partially suppressed in the treated group (p < 0.001), and this effect was most marked in patients with July levels less than 36 ng/ml. Levels of IgG antibody to AgE in the treated patients were approximately 70-fold greater than in untreated patients and showed little change over the study period. The levels of IgG and IgE antibody in the treated patients were positively correlated (p < 0.001) at all time periods, and patients with high levels of IgG antibody also had greater declines and rises in IgE antibodies. The results indicate that immunotherapy is associated with (1) a reduction in the seasonal decrease in IgE antibody from October to July in patients with the low levels of IgE antibody, (2) a partial suppression of the rises in IgE antibody from July to October, and (3) that both these effects are related to the level of IgE antibody before the change. In many treated patients both IgE and IgG antibodies were low in spite of parenteral administration of ragweed extract. This result is consistent with the view that overall humoral immunologic reactivity to ragweed antigens is reduced in these patients.     

Hazelnut Allergy: evidence that hazelnut can directly elicit specific IgE antibody response via activating type 2 cytokines in mice

BACKGROUND: Hazelnut is one of the major tree nuts that causes potentially fatal food allergy, with underlying mechanisms that are unclear at present. One suggestion is that hazelnut allergy results from immune crossreactivity of IgE antibodies produced against certain aeroallergens. We tested the hypothesis that hazelnut is intrinsically capable of eliciting an allergic response using a mouse model. METHODS: Groups of mice were injected intraperitoneally with hazelnut/filbert protein extract with or without alum as an adjuvant, and hazelnut-specific antibody (IgE, IgG1) responses were examined using optimized enzyme-linked immunosorbent assay. Hazelnut-specific type 2 and type 1 cytokine responses were evaluated by ex vivo antigen-mediated activation of spleen cells. RESULTS: Hazelnut elicited robust IgE and IgG1 antibody responses. Timecourse and dose-response analyses further provided evidence for memory type 2-dependent antibody responses to hazelnuts. Hazelnut-specific IgE response in two strains of mice with different MHC haplotypes and IgE response to hazelnut without the use of alum adjuvant asserted that hazelnut is intrinsically an allergenic food. The type 2 cytokine analyses revealed that hazelnut sensitization results from activation of IL-4 and IL-5, thus providing a mechanistic basis for hazelnut-specific IgE response. CONCLUSION: Our data argue that hazelnut - a widely consumed food - is intrinsically an allergenic food capable of directly eliciting hazelnut-binding specific IgE antibodies viaactivation of type 2 cytokines in mice.     

Effect of seasonal exposure to pollen on specific bronchial sensitivity in allergic patients

Bronchial provocation tests with aerosol of birch extract were performed before and after pollen season in 11 sensitized subjects. Changes of metacholine bronchial responsiveness and serum-specific IgE level were also assessed. In five patients who did not take steroids to control their symptoms, both early and late asthmatic responses to inhaled allergen were enhanced after season, whereas IgE serum level, but not methacholine sensitivity, was significantly increased. In six patients who needed steroids, neither responses to allergen nor IgE serum level and methacholine sensitivity were significantly changed after season. For the whole group, the increase in immediate bronchial sensitivity to allergen was positively correlated with the increase in specific IgE antibodies. We conclude that seasonal exposure to pollen has, in sensitized patients, a priming effect on bronchial mucosa that may be blunted by steroid treatment. The increased production of specific IgE antibodies appears to be an important mechanism for this priming effect.     

Evolution of IgM, IgE and IgG(1-4 )antibody responses in early childhood monitored with recombinant allergen components: implications for class switch mechanisms

The formation of IgE antibodies against environmental allergens represents the hallmark of type I allergy. Data from in vitro cultured cells and experimental animal models provide controversial evidence for isotype switching from IgM to IgE production via sequential as well as non-sequential (i.e. direct) class switch. We analyzed the evolution of IgE responses in 11 children developing birch pollen and/or grass pollen allergy during the first 7 years of life using purified recombinant allergen molecules (major birch pollen allergen, Bet v 1; major timothy grass pollen allergens, Phl p 1, Phl p 2, Phl p 5). Demographic, clinical and serological data indicated a postnatal sensitization to pollen allergens. A parallel development of IgG(1-4) and IgE responses to recombinant allergen molecules compatible with a strictly sequential class switch to IgE was observed only in one child. The only partly synchronized and dissociated development of allergen-specific antibody responses found in all other cases can be best explained by a partly sequential class switch involving few switch stations or, more likely, by direct class switching. Kinetics and courses of allergen-specific antibody responses (IgM, IgG(1-4), IgE) during the first years of life suggest that, once established, allergen-specific IgE responses are driven by antigen contact rather than by cytokines controlling class switch to IgE.     

Adjuvant activity of diesel-exhaust particulates for the production of IgE antibody in mice

The prevalence rate of allergic rhinitis caused by pollen has strikingly increased in Japan in the last three decades. The number of diesel cars in use has also rapidly increased in the country. This fact urged us to study the effects of particulates emitted from diesel cars on the production of IgE antibody. The primary IgE antibody responses in mice immunized with intraperitoneal injection of ovalbumin (OA) mixed with diesel-exhaust particulates (DEP) were higher than those in the animals immunized with OA alone. This effect of DEP on the production of IgE antibody in mice was also demonstrated when mice were immunized with repeated injections of dinitrophenylated-OA. In addition, persistent IgE-antibody response to major allergen of Japanese cedar pollen (JCPA), a most common pollen causing allergic rhinitis in Japan, was observed in mice immunized with JCPA mixed with DEP but not in the animals immunized with JCPA alone. The results do indicate that the adjuvant activity of DEP can not be excluded as a possible cause of the associated change in the number of diesel cars and allergic rhinitis caused by pollen in Japan.     

Suppression of the IgE antibody response in mice to kentucky blue grass pollen allergens

Reagins in murine strains A/HeJ, RF/J C3H/HeJ and B6D2F1 were induced by immunization, in the presence of A1(OH)3, with the retentate (R) obtained by dialysis from the aqueous extract of Kentucky blue grass pollen (KBG-Aq. ext.). Administration of doses of R ranging from 50-200 microgram resulted in IgE antibody responses which were sustained for periods of the order of 6 months. The possibility of suppressing the anti-R IgE antibody response in sensitized A/HeJ mice was tested by the administration into these animals for a period of 14 weeks, biweekly injections of a skin-active, immunogenic fraction (DI) isolated from the dialysate of KBG-Aq. ext. This treatment effectively suppressed the secondary IgE antibody response to R and markedly increased levels of hemagglutinating antibodies. On the basis of the fact that DI comprised only 1.5% of the parent fraction KBG-Aq. ext. and since it was capable of modulating the immune response to R as described, it is suggested that DI may prove to be a useful agent for the immunotherapy of allergies to KBG pollen.     

The proliferative response and immunoglobulin production in peripheral blood lymphocytes stimulated with Japanese cedar pollen antigens]

Peripheral blood mononuclear cells taken from 38 normal subjects and 50 Japanese cedar pollinosis patients were cultured with or without mitogens or Japanese cedar pollen antigens to study the proliferative response and immunoglobulin production in periphral blood lymphocytes. When stimulated with Con A or anti-CD 40 mAb, the proliferative responses in the patient group were significantly higher than those in the normal group, and when stimulated with anti-CD 40 mAb, the IgG 2 production was markedly dominant among the IgE and IgG subclass productions in both groups. When stimulated with Japanese cedar pollen antigens, the proliferative responses in the patient group were markedly augmented in comparison with the normal group, and showed a correlation with the serum anti-cedar IgE antibody titers in the patient group. In regard to the immunoglobulin production in peripheral blood lymphocytes stimulated with Japanese cedar pollen antigens, the IgE productions in the patient group were significantly higher than those in the normal group, and showed a weak correlation with the serum anti-cedar IgE antibody titers in the patient group. The IgG productions were, however, slightly enhanced by the stimulation with Japanese cedar pollen antigens in both of the normal and patient groups. While it could not be clearly demonstrated which subclass of IgG was responsible for the enhancement of IgG production, there were some cases of relatively higher responses of IgG 2 or IgG 4 production. Though the IgG 4 productions in the patient group were significantly higher than those in normal group, there was no clear correlation with the serum anti-cedar IgE antibody titers in the patient group. On the other hand, it seems to be noteworthy that a weak negative correlation was recognized between the IgG 2 productions and the IgG 4 productions, and between the IgG 4 productions and the IgE productions. Considering these results in the present study, it was concluded to be difficult to identify a IgG 4 high responder in a course of clinical immunotherapy through the in vitro IgG 4 production or other related reactions as attempted in this study.     

In vitro production of IgE by human peripheral blood mononuclear cells. IV. Modulation by allergen of the spontaneous IgE antibody biosynthesis.

Peripheral blood lymphocytes (PBL) from a proportion of grass-sensitive patients, studied during or immediately after the grass pollination period, showed spontaneous production in vitro of grass-specific IgE antibody, whereas PBL from atopic patients sensitive to allergens other than grass pollens or non-atopic individuals did not. Pre-incubation of IgE antibody producing PBL from grass-sensitive patients with minute amounts of a mixed grass pollen (MGP) extract or Rye grass antigen Group I (Rye I) usually resulted in a reduction of the spontaneous production in vitro of IgE protein and in a marked inhibition of the spontaneous production in vitro of grass-specific IgE antibody. This antigen-specific inhibition was not mediated by T lymphocytes, but it was apparently due to a signal directly delivered by antigen to the spontaneously IgE antibody producing cells. The results support the concept that the activity of cells responsible for the persistent IgE antibody formation in vitro in atopic patients can be modulated by antigen.     

A Case of Occupational Rhinitis Induced by Maize Pollen Exposure in a Farmer: Detection of IgE-Binding Components

Corn is a major staple food, along with rice and wheat, in many parts of the world. There are several reports of hypersensitivity to maize pollen. However, cases of occupational allergic rhinitis induced by inhalation of maize pollen are very rare. We herein report the case of a 67-year-old male with occupational rhinitis caused by occupational exposure to maize pollen in a cornfield. He showed positive responses to maize pollen, as well as grass pollens, in skin prick tests. A high level of serum immunoglobulin E (IgE) specific to maize pollen extracts was detected by an enzyme-linked immunosorbent assay (ELISA). Laboratory tests showed a high serum level of total IgE (724 kU/L) and a high level of IgE specific to maize pollen (8.32 kU/L) using the Immuno-CAP system. Occupational rhinitis was confirmed by a nasal provocation test with maize pollen extracts. IgE ELISA inhibition tests showed antibody cross-reactivity between maize pollen and grass pollen extracts. IgE immunoblotting using maize pollen extracts demonstrated a 27 kDa IgE-binding component. These findings suggest that maize pollen can induce IgE-mediated occupational rhinitis in exposed workers.     

Oral tolerance induction in dermatophagoides pteronyssinus-sensitized mice induces inhibition of IgE response and upregulation of TGF-beta secretion.

Oral antigen administration induces peripheral tolerance in naive animals. Studies of oral tolerance induction in sensitized mice have clinical relevance as a strategy to modulate allergy. In this study, the A/Sn mice sensitized with extract of Dermatophagoides pteronyssinus (Dp) and submitted to oral Dp administration showed a marked decrease in IgE anti-Dp antibody production compared with sensitized phosphate-buffered saline (PBS)-fed mice. T cells from Dp-fed mice cocultured with spleen cells from PBS-fed mice were able to inhibit IgE anti-Dp antibody production and did not interfere in IgG1 antibody levels. The analysis of cytokine profile after Dp feeding showed a significant decrease in interleukin-4 (IL-4), IL-5, and IL-13 antigen-induced secretion levels by spleen cells, without shifting to IL-2 and interferon-gamma (IFN-gamma) production. Both transforming growth factor-beta (TGF-beta) baseline and TGF-beta antigen-stimulated levels were increased in Dp-fed mice. The effects of regulatory cytokines on anti-Dp IgE antibody production were investigated in vitro. The addition of recombinant TGF-beta (rTGF-beta) to spleen cell cultures stimulated by Dp inhibited IgE antibody secretion in both mouse groups. Neutralizing antibodies to IL-4, but not anti-TGF-beta, induced a marked inhibition of IgE production. Therefore, a negative modulatory effect on IgE response by inhibition of the axis Th2 was observed in sensitized Dp-fed mice, possibly mediated by induction of regulatory cytokines.     

Shorter Dosing Intervals of Sublingual Immunotherapy Lead to More Efficacious Treatment in a Mouse Model of Allergic Inflammation

Current day practice of sublingual immunotherapy (SLIT) includes varying modalities of treatment that differ with regard to formulation, dosing and administration regimens. The aim of this study was to explore the importance of the dosing intervals in SLIT. The immunological effect of increased SLIT dosing frequency was tested in a mouse model of allergic inflammation. Mice sensitized to Phleum pratense (Phl p) were SLIT‐treated with the same weekly cumulative dose administered with different administration frequencies. A SLIT sham‐treated group was also included. All mice were challenged intra‐nasally with Phl p extract following SLIT. Local and systemic cytokine production, eosinophil infiltration into airways and the development of Phl p‐specific antibody responses were determined. Higher frequency of sublingual administration of allergen extract has a profound positive impact on the effect of SLIT, measured as induction of IgG and IgA antibodies. The once daily SLIT was the only treatment regimen being able to reduce all systemic Th2 cytokines and systemic IgE antibody responses when compared to sham‐treated mice after the intra‐nasal challenge period. The group receiving SLIT with the highest frequency of administration had the most pronounced effect of the treatment. In the same group, there was also a higher degree of protection against increase in IgE antibody levels after intra‐nasal challenge with the allergen, our data demonstrate that a once daily regimen is more efficacious than regimens where SLIT, with the same weekly cumulative allergen dose, is administered with longer intervals but higher doses.     

Suppressive versus stimulatory effects of allergen/cholera toxoid (CTB) conjugates depending on the nature of the allergen in a murine model of type I allergy.

Recent reports have demonstrated that feeding small amounts of antigen conjugated to the B subunit of cholera toxin (CTB) suppress immune responses in experimental models of certain Th1-based autoimmune diseases. We have established a model of aerosol sensitization leading to Th2-mediated allergic immune responses in BALB/c mice. In the present study two different antigens, the dietary antigen ovalbumin (OVA) and the inhalant allergen Bet v 1 (the major birch pollen allergen), chemically coupled to recombinant CTB were tested for their potential to influence Th2-like immune responses. Intranasal administration of OVA-CTB prior to sensitization with OVA led to a significant decrease of antigen-specific IgE antibody levels, but a marked increase of OVA-specific IgG2a antibodies as compared to non-pretreated, sensitized animals. Antigen-specific lympho-proliferative responses in vitro were reduced by 65% in the pretreated group; IL-5 and IL-4, but not IFN-gamma, production were markedly decreased in responder cells of lungs and spleens of nasally pretreated mice. In contrast, mucosal administration of rBet v 1-CTB conjugates prior to sensitization led to an up-regulation of allergen-specific IgE, IgG1 and IgG2a, increased in vitro lympho-proliferative responses as well as augmented production of IL-5, IL-4, IL-10 and IFN-gamma. Intranasal administration prior to sensitization of unconjugated allergens showed also contrasting effects: OVA could not significantly influence antigen-specific antibody or cytokine production, whereas intranasal pretreatment with unconjugated Bet v 1 suppressed allergen-specific immune responses in vivo and in vitro. These results demonstrated that the two antigens--in conjugated as in unconjugated form--had different effects on the Th2 immune responses. We therefore conclude that the tolerogenic or immunogenic properties of CTB--and probably also other antigen-delivery systems--strongly depend on the nature of the coupled antigen-allergen.     

Immunostimulatory oligodeoxynucleotide induces TH1 immune response and inhibition of IgE antibody production to cedar pollen allergens in mice

BACKGROUND: Immunotherapy for cedar pollinosis makes use of multiple injections of allergens, but its effectiveness remains controversial. Recent studies indicate that immunization with certain protein antigens and immunostimulatory DNA sequence (ISS) oligodeoxynucleotides (ODNs) represent a potential approach to allergen-specific immunotherapy. OBJECTIVE: We determined whether the coadministration of 2 major protein allergens, Cry j 1 and Cry j 2, of Japanese cedar pollen and ISS-ODN (5'-TGACTCTGAACGTTCGAGATGA-3') improves the immune responses induced by protein allergens in BALB/c mice. METHODS: Mice were primed intradermally with allergens or ISS-ODN in saline solution and boosted with allergens in alum, and other mice were primed with allergens in alum and boosted with allergens/ISS-ODN. Allergen-specific IgG2a and IgG1 antibody responses were measured by means of ELISA in sera after ODN injection, and allergen-specific IgE antibody production was measured by the passive cutaneous anaphylaxis reaction. IFN-gamma and IL-4 releases were also measured by ELISA in the supernatants of allergen-stimulated spleen cells. RESULTS: The coadministration of allergens/ISS-ODN increased IgG2a titers and IFN-gamma release in both groups of mice, whereas it decreased IgG1 titers and IL-4 release in comparison with control mice injected with allergens/mutant ODN. The coadministration additionally inhibited IgE antibody production. CONCLUSION: The data demonstrate that the coadministration of cedar pollen allergens and ISS-ODNs before secondary T(H2) and IgE responses or during ongoing primary T(H2) and IgE responses brings about a T(H1)-shifted immune response and inhibition of IgE antibody production, suggesting that this coadministration strategy may provide a novel type of immunotherapy for cedar pollinosis.     

Intranasal administration of allergen increases specific IgE whereas intranasal omalizumab does not increase serum IgE levels—A pilot study

Background

Administration of the therapeutic anti‐IgE antibody omalizumab to patients induces strong increases in IgE antibody levels.

Objective

To investigate the effect of intranasal administration of major birch pollen allergen Bet v 1, omalizumab or placebo on the levels of total and allergen‐specific IgE in patients with birch pollen allergy.

Methods

Based on the fact that intranasal allergen application induces rises of systemic allergen‐specific IgE, we performed a double‐blind placebo‐controlled pilot trial in which birch pollen allergic subjects were challenged intranasally with omalizumab, placebo or birch pollen allergen Bet v 1. Total and allergen‐specific IgE, IgG and basophil sensitivity were measured before and 8 weeks after challenge. For control purposes, total, allergen‐specific IgE levels and omalizumab‐IgE complexes as well as specific IgG levels were studied in subjects treated subcutaneously with either omalizumab or placebo. Effects of omalizumab on IgE production by IL‐4/anti‐CD40‐treated PBMCs from allergic patients were studied in vitro.

Results

Intranasal challenge with Bet v 1 induced increases in Bet v 1‐specific IgE levels by a median of 59.2%, and this change differed significantly from the other treatment groups (P = .016). No relevant change in allergen‐specific and total IgE levels was observed in subjects challenged with omalizumab. Addition of omalizumab did not enhance IL‐4/anti‐CD40‐induced IgE production in vitro. Significant rises in total IgE (mean IgE before: 131.83 kU/L to mean IgE after: 505.23 kU/L) and the presence of IgE‐omalizumab complexes were observed after subcutaneous administration of omalizumab.

Conclusion

Intranasal administration of allergen induced rises of allergen‐specific IgE levels, whereas intranasal administration of omalizumab did not enhance systemic total or allergen‐specific IgE levels.     

Suppressive versus stimulatory effects of allergen/cholera toxoid (CTB) conjugates depending on the nature of the allergen in a murine model of type I allergy.

Recent reports have demonstrated that feeding small amounts of antigen conjugated to the B subunit of cholera toxin (CTB) suppress immune responses in experimental models of certain T(h)1-based autoimmune diseases. We have established a model of aerosol sensitization leading to T(h)2-mediated allergic immune responses in BALB/c mice. In the present study two different antigens, the dietary antigen ovalbumin (OVA) and the inhalant allergen Bet v 1 (the major birch pollen allergen), chemically coupled to recombinant CTB were tested for their potential to influence T(h)2-like immune responses. Intranasal administration of OVA-CTB prior to sensitization with OVA led to a significant decrease of antigen-specific IgE antibody levels, but a marked increase of OVA-specific IgG2a antibodies as compared to non-pretreated, sensitized animals. Antigen-specific lympho-proliferative responses in vitro were reduced by 65% in the pretreated group; IL-5 and IL-4 production were decreased in responder cells of lungs and spleens of nasally pretreated mice. In contrast, mucosal administration of rBet v 1-CTB conjugates prior to sensitization led to an up-regulation of allergen-specific IgE, IgG1 and IgG2a, increased in vitro lympho-proliferative responses as well as augmented production of IL-5, IL-4, IL-10 and IFN-gamma. Intranasal administration prior to sensitization of unconjugated allergens showed also contrasting effects: OVA could not significantly influence antigen-specific antibody or cytokine production, whereas intranasal pretreatment with unconjugated Bet v 1 suppressed allergen-specific immune responses in vivo and in vitro. These results demonstrated that the two antigens-in conjugated as in unconjugated form-had different effects on the T(h)2 immune responses. We therefore conclude that the tolerogenic or immunogenic properties of CTB-and probably also other antigen-delivery systems-strongly depend on the nature of the coupled antigen-allergen.