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.     

Reducing allergenicity by altering allergen fold: a mosaic protein of Phl p 1 for allergy vaccination

Background:  The major timothy grass pollen allergen, Phl p 1, resembles the allergenic epitopes of natural group I grass pollen allergens and is recognized by more than 95% of grass-pollen-allergic patients. Our objective was the construction, purification and immunologic characterization of a genetically modified derivative of the major timothy grass pollen allergen, Phl p 1 for immunotherapy of grass pollen allergy.
Methods:  A mosaic protein was generated by PCR-based re-assembly and expression of four cDNAs coding for Phl p 1 fragments and compared to the Phl p 1 wild-type by circular dichroism analysis, immunoglobulin E (IgE)-binding capacity, basophil activation assays and enzyme-linked immunosorbent assay competition assays. Immune responses to the derivative were studied in BALB/c mice.
Results:  Grass-pollen-allergic patients exhibited greater than an 85% reduction in IgE reactivity to the mosaic as compared with the Phl p 1 allergen and basophil activation experiments confirmed the reduced allergenic activity of the mosaic. It also induced less Phl p 1-specific IgE antibodies than Phl p 1 upon immunization of mice. However, immunization of mice and rabbits with the mosaic induced IgG antibodies that inhibited patients' IgE-binding to the wild-type allergen and Phl p 1-induced degranulation of basophils.
Conclusion:  We have developed a strategy based on rational molecular reassembly to convert one of the clinically most relevant allergens into a hypoallergenic derivative for allergy vaccination.     

Allergen-specific immunotherapy with recombinant grass pollen allergens

BACKGROUND: Allergen-specific immunotherapy uses aqueous extracts of natural source materials as a basis for preparations to down regulate the allergic response. Recombinant DNA technology has enabled the cloning of many allergens, thus facilitating investigations aimed at improving efficacy and safety of immunotherapy. OBJECTIVE: To determine the effectiveness of a mixture of 5 recombinant grass pollen allergens in reducing symptoms and need for symptomatic medication in patients allergic to grass pollen. METHODS: A randomized, double-blind, placebo-controlled study of subcutaneous injection immunotherapy was performed in subjects with allergic rhinoconjunctivitis, with or without asthma. Primary endpoint was a symptom medication score compiled from separate symptom and medication scores. Secondary endpoints included a rhinitis quality of life questionnaire, conjunctival provocation, and specific antibody responses. RESULTS: The symptom medication score showed significant improvements in subjects receiving recombinant allergens as opposed to placebo, with reductions in both symptoms and medication usage. The rhinitis quality of life questionnaire revealed clinically relevant significant improvements in overall assessment and in 5 of 7 separate domains, and conjunctival provocation showed a clear trend in favor of active treatment. All treated subjects developed strong allergen-specific IgG(1) and IgG(4) antibody responses. Some patients were not sensitized to Ph l p 5 but nevertheless developed strong IgG antibody responses to that allergen. CONCLUSION: A recombinant allergen vaccine can be a effective and safe treatment to ameliorate symptoms of allergic rhinitis. The clinical benefit is associated with modification of the specific immune response with promotion of IgG(4) and reduction of IgE antibodies consistent with the induction of IL-10-producing regulatory T cells.     

Allergen-specific immunotherapy with a monophosphoryl lipid A-adjuvanted vaccine: reduced seasonally boosted immunoglobulin E production and inhibition of basophil histamine release by therapy-induced blocking antibodies

BACKGROUND: Allergen-specific immunotherapy represents a causal form of treatment for IgE-mediated allergies. The allergen extract-based analyses of immunotherapy-induced effects yielded highly controversial results regarding a beneficial role of therapy-induced IgG antibodies. OBJECTIVE: We analysed allergen-specific IgE, IgG subclass, and IgM responses in patients treated with a grass pollen allergy vaccine adjuvanted with monophosphoryl lipid A (MPL), a Th1-inducing agent, and in a placebo group using recombinant timothy grass pollen allergen molecules (rPhl p 1, rPhl p 2, rPhl p 5). RESULTS: The strong induction of allergen-specific IgG1 and IgG4 antibodies observed only in the actively treated group was associated with significant clinical improvement. Therapy-induced allergen-specific IgM and IgG2 responses were also noted in several actively treated patients. An inhibition of allergen-dependent basophil histamine release was only obtained with sera containing therapy-induced allergen-specific IgG, but not with sera obtained before therapy or from placebo-treated patients. Moreover, patients with therapy-induced allergen-specific IgG antibodies showed a reduced induction of allergen-specific IgE responses during seasonal grass pollen exposure. CONCLUSION: Successful immunotherapy with the MPL-adjuvanted grass pollen allergy vaccine is associated with the production of allergen-specific IgG antibodies. These blocking antibodies may have protective effects by inhibiting immediate-type reactions and systemic increases of IgE responses caused by seasonal allergen exposure.     

Immunotherapy with a calcium phosphate-adsorbed five-grass-pollen extract in seasonal rhinoconjunctivitis: a double-blind, placebo-controlled study

BACKGROUND: Calcium phosphate-adsorbed allergen extracts are used for subcutaneous immunotherapy to avoid the use of aluminium adjuvants. OBJECTIVES: A double-blind, placebo-controlled study was performed in order to confirm the safety and assess the efficacy of a standardized five-grass-pollen extract adsorbed onto calcium phosphate for specific immunotherapy (IT). METHODS: Twenty-nine patients with seasonal rhinoconjunctivitis were randomized to receive either the active preparation (16 patients) or placebo (13 patients), in a 1-year study. During the increasing dose phase, an extract ranging from 0.1 IR per ml to 50 IR per ml was administered at a rate of one subcutaneous injection per week until a maintenance dose was reached. The patients were assessed by symptom diary and rescue medications during seasonal exposure and specific nasal and skin reactivity before and after IT. Immunological parameters (specific IgE and IgG4 antibodies) were assessed before, during and after IT. RESULTS: The overall symptoms score (mean AUC) was not significantly different between the IT group and the placebo group during grass-pollen exposure (49.6 vs. 56, respectively). The total medication score (mean AUC) was significantly lower in the IT group than in the placebo group (11 vs. 41, P < 0.01, Mann-Whitney U-test). The cumulative symptom/medication score was significantly lower in the IT group than in the placebo group (64.5 vs. 102.3, P < 0.05, U-test). A significant increase in nasal reactivity threshold was observed after IT in the IT group (21. 4 IR/mL before IT vs. 63.4 IR/mL after IT, P < 0.01, Wilcoxon), whereas no significant changes were observed in the placebo group (31.0 IR/mL before IT vs. 37.7 IR/mL after IT). IT induced a significant reduction in grass pollen cutaneous reactivity in the actively treated group (P < 0.001). A significant increase in serum-specific IgG4 antibody response was observed in the IT group (3.1% before IT vs. 10.1% after IT, P < 0.001). Nine patients in the IT group developed moderate immediate systemic reactions vs. two patients in the placebo group. CONCLUSION: Specific immunotherapy with calcium phosphate-adsorbed standardized grass pollen extract was safe and effective for the treatment of patients with seasonal allergic rhinoconjunctivitis.     

Use of glutaraldehyde-modified timothy grass pollen extract in nasal hyposensitisation treatment of hay fever.

12 patients suffering from grass pollen hay fever were treated for 14 weeks pre- and co-seasonally by intranasal self-administration of an aqueous solution of a glutaraldehyde-treated timothy grass pollen allergen. These patients had a statistically significant decrease in nasal symptom scores during the grass pollen peak period and in nasal challenge end-point titre after the season compared to placebo-treated patients. No significant effect was seen on the eye symptoms. 1 patient withdrew from the trial as a consequence of too strong local nasal reactions during treatment. Most other patients treated with active material reported mild local reactions during the first minutes after administration of the nasal spray. In the actively treated group a significant increase in serum and nasal secretion of grass pollen specific IgE, IgG and IgA antibodies was obtained during the treatment. In contrast, in the placebo group a significant increase in IgE antibody levels in serum and secretion occurred during the pollen season. The reduction in symptoms and increase in antibody production together with the simplicity of the procedure makes this approach to immunotherapy attractive.     

Specific immunotherapy with SQ standardized grass allergen tablets in asthmatics with rhinoconjunctivitis

BACKGROUND: The best way to prevent allergy symptoms is to treat the allergic condition. Specific immunotherapy with grass allergen tablets 75,000 SQ-T (Grazax, Phleum pratense, ALK-Abelló) is safe and efficacious in rhinoconjunctivitis patients. As rhinoconjunctivitis often co-exists with asthma, we aimed to confirm safety and efficacy in grass allergic subjects with asthma and rhinoconjunctivitis. METHODS: A randomized, double-blind, placebo-controlled, multicentre trial was performed 10-14 weeks prior to and during the grass pollen season 2004. About 114 subjects were randomized 2 : 1 to grass allergen tablets or placebo. The primary end points were average asthma medication and symptom scores during the grass pollen season, and secondary variables were average rhinoconjunctivitis symptom and medication scores during the grass pollen season. Additionally, number of well days was defined post hoc. RESULTS: Differences in asthma medication and symptom scores between the treatment groups were negligible. The mean difference in asthma medication score was below 0.1 and 0.3 for asthma symptom score [a single inhalation of salbutamol (200 microg) was scored 2]. No serious adverse events were reported. A reduction in rhinoconjunctivitis symptom score of 37% (P = 0.004) and a 41% (P = 0.036) reduction in medication score was found in the grass pollen season for subjects treated with the grass allergen tablet compared with placebo. Well days increased by 54% (P = 0.002). CONCLUSIONS: Self-administration of the grass allergen tablet was safe. The treatment did not impair asthma control and confirmed considerable symptom prevention and reduced medication use. It addresses the allergic condition and represents a baseline treatment for grass pollen allergy.     

Analysis of the sensitization profile towards allergens in central Africa

BACKGROUND: Almost no information is available regarding the prevalence of IgE-mediated allergies and the disease-eliciting allergens in tropical Africa. OBJECTIVE: To study IgE-mediated allergies and the allergen profile in allergic patients from Zimbabwe. METHODS: The frequency of sensitization to common environmental allergen sources was determined by skin prick testing in 650 allergic patients from Zimbabwe. Fifty representative sera were analysed for IgE reactivity to 20 respiratory and 20 food allergen extracts by multiallergen extract testing. The IgE reactivity profiles to recombinant pollen and mite allergens were compared between grass pollen- and mite-sensitized patients from Zimbabwe and central Europe. Sera from grass pollen-allergic patients were also analysed for IgE reactivity to nitrocellulose-blotted natural timothy grass and Bermuda grass pollen allergens. RESULTS: IgE-mediated allergies were found to be common in Zimbabwe. Similar to the situation in central Europe, mites and grass pollens represented the most prevalent allergen sources. However, the IgE reactivity profiles determined with single recombinant pollen and mite allergens revealed interesting differences between the European and African patients, which most likely reflect the local allergen exposure. CONCLUSIONS: The striking differences regarding sensitization to grass pollen and mite allergens between African and European patients revealed by recombinant allergen-based testing emphasize the need for component-resolved allergy testing to optimize allergy prevention and therapy in different populations.     

Possible therapeutic potential of a recombinant group 2 grass pollen allergen‐specific antibody fragment

The induction of blocking IgG antibodies that compete with IgE for allergen binding is one important mechanism of allergen‐specific immunotherapy. The application of blocking antibodies may be an alternative treatment strategy. A synthetic gene coding for a single‐chain fragment (ScFv) specific for the major timothy grass pollen allergen Phl p 2 was inserted into plasmid pCANTAB 5 E, and the recombinant ScFv was expressed in Escherichia coli and purified by affinity chromatography. The ScFv was tested for allergen binding by ELISA, and its association and dissociation were measured by surface plasmon resonance (Biacore) technology. The ability of the ScFv to inhibit allergic patients' IgE binding to Phl p 2 and Phl p 2‐induced basophil degranulation was studied by ELISA competition and basophil activation (CD203c) assays. We report the expression, purification, biochemical and immunological characterization of a monomeric single‐chain fragment (ScFv) of human origin specific for the major timothy grass pollen allergen, Phl p 2. The Phl p 2‐ScFv showed high affinity binding to the allergen and blocked the binding of allergic patients' polyclonal IgE to Phl p 2 up to 98%. Furthermore, it inhibited allergen‐induced basophil activation. The Phl p 2‐ScFv inhibited allergic patients' IgE binding to Phl p 2 as well as Phl p 2‐induced basophil activation and might be useful for passive immunotherapy of grass pollen allergy.     

Immunotherapy in Hay Fever with Two Major Allergens 19, 25 and Partially Purified Extract of Timothy Grass Pollen

Grass pollen hay fever patients were hyposensitized in a prospective 3-year double blind study with two timothy extracts. Group WPA (20 patients) was treated with partially purified extract = whole pollen allergens (WPA) (Alutard®SQ) and group PPA (20 patients) was treated with a purified pollen allergen (PPA) = two isolated major allergens, Ag19 and Ag25. Both aluminiumhydroxide adsorbed extracts were biologically standardized. Clinical results from the first season have been recently published and WPA showed significantly fewer symptoms (P= 0.001) than PPA. Corresponding preseasonal and seasonal in vitro results are presented here. Serum total IgE, specific IgE versus total and individual allergens of timothy pollen and allergen-specific IgG showed a rapid increase in both groups until the season but showed no further increase or decrease during the season. Specific IgE was shown to correlate to specific IgG during hyposensitization. Group WPA, with fewer symptoms in grass pollen season than group PPA showed a significantly higher increase of specific IgG and IgE than group PPA, but individual symptom scores were not correlated to specific IgG or IgE, or their ratio. Specific IgE and IgG increases were not correlated to dosage. Surprisingly, almost all females were low-responders to specific IgG and IgE though they had equal symptom scores, dosage, and side effects as males, while the characteristics of high-responders to antibody were: youngest individuals and shortest duration of symptoms prior to treatment. Crossed radioimmunoelectrophoresis (CRIE) showed specific reaction to stimuli but no development of allergy against new timothy antigens. High response of IgE to Ag 19 in CRIE during initial hyposensitization seems suitable as marker for prospective evaluation of clinical effect in grass pollen hyposensitization. Nasal secretion was collected after methacholine provocation, and total IgE and specific IgE detected. There was no response to treatment, only a slight increase during the season. No decrease in nasal reactivity to methacholine was noted during one preseasonal hyposensitization.     

Hyposensitization

Most extracts used in hyposensitization (immunotherapy) are complex and ill-denned mixtures of a large number of non-antigenic and antigenic components, only a few of the latter being of significance for allergy and allergen specific immunotherapy. A new purified and well-characterized allergen preparation from timothy pollen is now available, and it has been shown to be superior to the corresponding crude aqueous extract in the diagnosis of IgE-mediated human allergy to timothy pollen.
This paper describes the results of hyposensitization for 2 years, with the purified preparation and the crude extract compared. The changes in in vivo and in vitro tests Following this treatment in 40 patients with allergic rhinitis due to grass pollen are reported.
Both patient groups showed a significant decrease in clinical symptom scores when compared with a control group during the grass pollen season. For all groups the symptom scores correlated well with atmospheric pollen counts. Nasal challenge tests showed a significant increase in nasal tolerance to timothy pollen after 2 years of treatment, but nasal tolerance was unchanged in the control group. Nasal function as a criterion for evaluating the effect of specific hyposensitization is discussed.
Serum concentrations of timothy pollen-specific IgE antibodies showed a significant decrease for the group treated with the purified preparation and a slighter and non-significant reduction for the other treated group. There was no significant change in total serum IgE levels.
The results indicate that the purified preparation is preferable to the crude aqueous extract in hyposensitization.     

Canadian trial of sublingual swallow immunotherapy for ragweed rhinoconjunctivitis.

BACKGROUND: Sublingual swallow immunotherapy has been increasingly recognized as a safe and efficacious alternative to parenteral specific immunotherapy. OBJECTIVE: To determine the safety and efficacy of sublingual swallow immunotherapy ragweed allergen extract for rhinoconjunctivitis treatment starting just before and continuing through the ragweed pollen season. METHODS: This randomized, double-blind, placebo-controlled study was performed in children and adults with a documented history of allergic rhinoconjunctivitis during ragweed season at 9 Canadian allergy centers. Active treatment was standardized extract of ragweed allergen administered as sublingual swallow drops at increasing doses starting shortly before the pollen season and maintenance doses continued daily during the season. Primary efficacy variables were symptom and medication scores, and secondary variables included global evaluation of efficacy and immunologic measurements. RESULTS: Eighty-three patients were included in the safety analysis; 76 patients were included in the intent-to-treat analysis. Nine placebo recipients and 1 treatment recipient withdrew for lack of efficacy (P = .004). Nine patients in the treatment group withdrew because of adverse events, none serious (P = .003). Investigator evaluation of efficacy showed that significantly more patients improved and fewer deteriorated in the treatment group vs the placebo group (P = .047). Ragweed IgE and IgG4 levels increased significantly in treatment recipients vs placebo users (P < .001). Sneezing and nasal pruritus approached significant improvement in the treatment group vs the placebo group (P = .09 and .06, respectively). Quebec City experienced low pollen counts. Excluding Quebec City, significant improvement was seen for these 2 symptoms (P = .04). CONCLUSION: Sublingual swallow immunotherapy seems to be safe and efficacious for ragweed rhinoconjunctivitis even when started immediately before the ragweed pollen season.     

Hyposensitization therapy with whole pollen extract or purified allergens monitored by immunoblotting.

Patients allergic to grass pollen were hyposensitized with two major allergenic components or whole extract of timothy grass pollen. Specific IgE, IgG1, and IgG4 formed during immunotherapy were analyzed by immunoblotting. Similar antibody-binding patterns were observed in both patient groups. Inhibition experiments using allergenic components isolated by preparative sodium dodecyl sulphate-polyacrylamide gel electrophoresis indicated that all antigenic components of timothy grass pollen detected in immunoblot dispose of private and cross-reactive determinants for binding of human IgE. The worse clinical outcome of immunotherapy after hyposensitization with two cross-reactive components did, therefore, not correlate with a specific antibody formation pattern.     

Conversion of grass pollen allergen-specific human IgE into a protective IgG(1) antibody

More than 100 million individuals exhibit IgE-mediated allergic reactions against Phl p 2, a major allergen from timothy grass pollen. We isolated cDNA coding for three Phl p 2-specific human IgE antibodies from a combinatorial library, which was constructed from lymphocytes of a grass pollen-allergic patient. Recombinant Phl p 2-specific IgE antibody fragments (Fab) recognized a fragment comprising the 64 N-terminal amino acids of Phl p 2 and cross-reacted with group 2 allergens from seven grass species. cDNA coding for the variable regions of one of the IgE Fab were cloned into aplasmid vector expressing the constant region of human IgG(1) to obtain a complete, recombinant Phl p 2-specific human IgG(1). This antibody blocked the binding of grass pollen-allergic patients IgE (n=26; mean inhibition: 58%) to Phl p 2 and caused a 100-fold reduction of Phl p 2-induced basophil histamine release. The recombinant human Phl p 2-specific IgG(1) may be used for environmental allergen detection, for standardization of diagnostic as well as therapeutic grass pollen allergen preparations and for passive therapy of grass pollen allergy.     

Sublingual immunotherapy with once-daily grass allergen tablets: a randomized controlled trial in seasonal allergic rhinoconjunctivitis

BACKGROUND: Specific immunotherapy is the only treatment modality that has the potential to alter the natural course of allergic diseases. Sublingual immunotherapy has been developed to facilitate access to this form of treatment and to minimize serious adverse events. OBJECTIVE: To investigate the efficacy and safety of sublingual grass allergen tablets in seasonal allergic rhinoconjunctivitis. METHODS: A multinational, multicenter, randomized, placebo-controlled trial conducted during 2002 and 2003. Fifty-five centers in 8 countries included 855 participants age 18 to 65 years who gave a history of grass pollen-induced allergic rhinoconjunctivitis and had a positive skin prick test and elevated serum allergen-specific IgE to Phleum pratense. Participants were randomized to 2500, 25,000, or 75,000 SQ-T grass allergen tablets (GRAZAX; ALK-Abelló, H?rsholm, Denmark) or placebo for sublingual administration once daily. Mean duration of treatment was 18 weeks. RESULTS: Average rhinoconjunctivitis scores during the season showed moderate reductions of symptoms (16%) and medication use (28%) for the grass allergen tablet 75,000 SQ-T (P = .0710; P = .0470) compared with placebo. Significantly better rhinoconjunctivitis quality of life scores (P = .006) and an increased number of well days (P = .041) were also observed. Efficacy was increased in the subgroup of patients who completed the recommended preseasonal treatment of at least 8 weeks before the grass pollen season (symptoms, 21%, P = .0020; and medication use, 29%, P = .0120). No safety concerns were observed. CONCLUSION: This study confirms dose-dependent efficacy of the grass allergen tablet. Although further studies are required, the greater tolerability of the tablet may permit immunotherapy to be available to a much broader group of patients with impaired quality of life caused by grass pollen allergy. CLINICAL IMPLICATIONS: For patients with grass pollen allergy, sublingual immunotherapy is well tolerated and can reduce symptoms and improve quality of life.     

Specific IgE serum concentration is associated with symptom severity in children with seasonal allergic rhinitis

Background: The impact of allergen‐specific and total IgE serum levels before and during the pollen season on symptom severity as well as efficacy of treatment with anti‐IgE requires further delineation. Methods: Birch and grass pollen allergic patients aged 6–17 years with seasonal allergic rhinitis (SAR) were analyzed for the association of IgE serum concentration with symptom severity and rescue medication use (combination: symptom load, SL) during the grass pollen season. Reference group A (n = 53) received placebo, while group B (n = 54) received Omalizumab (anti‐IgE) monotherapy before and during the grass pollen season. Results: Patients on placebo with high baseline specific grass pollen IgE (>50 kU/l) had a significantly higher SL compared with those with low IgE levels (≤50 kU/l): SL 1.28 vs 0.61, P = 0.015. This association was nonexistent in patients treated with anti‐IgE. In contrast, baseline total IgE levels did not correlate with SL in any group. Patients with anti‐IgE treatment and high free total IgE levels (>16.7 ng/ml) had a significantly higher SL compared with those with low free total IgE levels (≤16.7 ng/ml): SL 0.63 vs 0.23, P = 0.031. Conclusions: Baseline specific IgE, but not total IgE, is associated with symptom severity during the pollen season in children with SAR. Likewise, the symptom load in SAR patients with anti‐IgE correlates with free total IgE levels. Although further research in larger populations is needed to confirm our findings, our data suggest that specific IgE can be used as a parameter for patient selection for this kind of treatment.     

Clinical effects of immunotherapy with genetically modified recombinant birch pollen Bet v 1 derivatives

Background Birch pollen and pollen from related trees of the Fagales order are a major cause of allergic rhinitis, conjunctivitis, and asthma through the spring season in northern and central Europe. Objective To investigate the clinical effects of injection immunotherapy with genetically modified derivatives of major birch pollen allergen Bet v 1 on pollen‐induced allergic symptoms. Methods A three‐arm double‐blind placebo‐controlled immunotherapy study was conducted with one pre‐seasonal course of treatment using two derivatives of Bet v 1, namely a recombinant Bet v 1 trimer and an equimolar mixture of two recombinant Bet v 1 fragments together representing the whole protein sequence. Analysis of local and systemic adverse events was performed for 124 patients who had received at least one dose of medication. Clinical efficacy was monitored by symptom medication scores and interval scoring in the per protocol‐treated population (n=84). In addition, skin and nasal provocation responses and allergen‐specific antibodies were assessed. Results There were trends towards improvement in the subjects' well‐being and clinical symptoms (nasal scores), although comparisons with a placebo group did not show statistical significance in the main end‐point, the combined symptom medication score. Reductions in skin and nasal sensitivity were observed for some subjects with a trend for the Bet v 1 trimer to be more effective than the fragments. Treatment induced strong IgG1 and IgG4 allergen‐specific antibody responses. Local injection‐site reactions were most frequent in the trimer group affecting 59.5% of patients as opposed to 37.8% and 30.6% in the fragment and placebo groups, respectively. Systemic reactions were elicited more frequently by fragments. A large proportion of adverse side‐effects appeared hours following injections, and might be attributable to concurrent exposure to related pollens. Conclusion Single courses of injection immunotherapy with Bet v 1 allergen derivatives showed trends towards improved well‐being and reduced reactivity to specific allergen provocation, but did not yield significant improvement in the combined symptom medication score in this study.     

The Role of Anti-IgE Therapy in Combination with Allergen Specific Immunotherapy for Seasonal Allergic Rhinitis

Novel therapies that interfere specifically with immunologic mechanisms underlying allergen-induced pathology are currently in clinical evaluation. Among these is anti-IgE, which directly targets IgE serum antibodies, thus inhibiting the central mechanism of immediate-type hypersensitivity reactions. Application of anti-IgE antibodies effectively reduces IgE serum levels regardless of allergen specificity. Anti-IgE therapy has been successfully tested in patients with allergic rhinitis, asthma, and food allergy, showing significant efficacy in reducing symptom scores and the use of rescue medications. However, such therapy is limited by high costs and the requirements for permanent or every-season treatment. The advantage of specific immunotherapy (SIT) is the potential to alter the course of the disease, which has been demonstrated in patients with allergic rhinitis, insect venom allergy and, to a lesser degree, asthma. The broader application of SIT is restricted by sometimes life-threatening adverse effects. The combination of anti-IgE with SIT was suggested to be superior to each single treatment protocol in children and adolescents with allergic rhinitis. In a randomized, double-blind trial to assess the efficacy and safety of anti-IgE (omalizumab) or placebo in combination with SIT (birch pollen or grass pollen), the combination therapy reduced symptom load, the sum of daily symptom severity score plus rescue medication use, over the birch and grass pollen seasons by nearly 50% over SIT alone. These data show that the combination of anti-IgE plus SIT may be beneficial for the treatment of allergic diseases, offering improved efficacy, limited adverse effects, and potential immune-modifying effects.     

The co-seasonal application of anti-IgE after preseasonal specific immunotherapy decreases ocular and nasal symptom scores and rescue medication use in grass pollen allergic children

BACKGROUND: Specific immunotherapy (SIT) and treatment with anti-immunoglobulin (Ig)E antibody are complementary approaches to treat allergic rhinoconjunctivitis, which may be used for single or combined treatment. OBJECTIVE: A randomized, double-blind, placebo-controlled trial was conducted to compare the efficacy of single and combined treatment with SIT and anti-IgE (Omalizumab) in reducing symptom severity and rescue medication use. METHODS: A total of 221 subjects with birch and grass pollen allergic rhinoconjunctivitis aged 6-17 years were analysed during the grass pollen season. Group A (SITbirch + placebo) served as a reference group obtaining no effective treatment for grass pollen allergy. Group B received anti-IgE monotherapy during grass pollen season, group C SIT grass pollen monotherapy, and group D the combined treatment of SIT and Omalizumab. RESULTS: Preseasonal treatment with grass pollen SIT alone compared with SIT with the nonrelated allergen did not reduce symptoms or rescue medication use. Anti-IgE monotherapy significantly diminished rescue medication use and number of symptomatic days. The combined treatment with SIT and anti-IgE showed superior efficacy on symptom severity compared with anti-IgE alone. CONCLUSIONS: Co-seasonal Omalizumab therapy showed considerable effects in children with seasonal allergic rhinitis. The combination of SIT plus Omalizumab was clinically superior to each treatment alone during the first year of observation.     

Inhibition of allergen-IgE binding to B cells by IgG antibodies after grass pollen immunotherapy

BACKGROUND: Among atopic individuals, levels of allergen-specific IgG antibodies have been inversely associated with the degree of allergen sensitization. Additionally, allergen-specific IgG antibodies are markedly increased by allergen injection immunotherapy. These observations have led to proposals that allergen-specific IgG antibodies might have protective properties in atopic individuals. OBJECTIVE: We hypothesized that after grass pollen immunotherapy, these antibodies disrupt IgE-dependent allergen processing by antigen-presenting cells. METHODS: We have developed a novel flow cytometric assay based on detection of allergen-IgE binding to the low-affinity IgE receptor on B cells to examine the blocking effects of sera collected from 18 patients who participated in a double-blind, controlled trial of grass pollen immunotherapy for 1 year. RESULTS: In all 10 patients who received active therapy, there was induction of activity that inhibited allergen-IgE binding to B cells (P =.02, vs placebo subjects), as well as subsequent allergen presentation to T cells. This activity copurified with IgG and was allergen specific, because sera taken from patients treated with grass pollen immunotherapy but who were also birch pollen sensitive did not inhibit IgE-birch pollen allergen binding to B cells. CONCLUSION: We conclude that allergen-specific IgG antibodies induced by immunotherapy can disrupt formation of allergen-IgE complexes that bind to antigen-presenting cells and facilitate allergen presentation.