Allergen immunotherapy: where is it now?

A meta-analysis investigating the efficacy and safety of allergen-specific immunotherapy in the management of respiratory allergies

BACKGROUND

This meta-analysis aimed to evaluate the effectiveness and adverse effects of specific immunotherapy (SIT) in the management of respiratory allergens, including allergic asthma, rhinitis, and related disorders, based on a review of current literature up to November 8, 2022.

METHODS

We conducted a search of databases, including PubMed, Embase, Cochrane, and Web of Science, to identify relevant randomized controlled trials (RCTs) assessing respiratory allergy-specific immunotherapy. We employed the Consolidated Standards of Reporting Trials (CONSORT) Statement to select RCTs that adhered to rigorous reporting standards. Specifically, we focused on double-blind placebo-controlled (DBPC) trials and open studies involving both adults and children, considering factors such as dosage, inclusion criteria, allergens, and primary outcome measurements.

RESULTS

A total of 25 meta-analyses were included in this study. Among them, 14 evaluated sublingual-specific allergen immunotherapy (SLIT), 4 assessed subcutaneous allergen immunotherapy (SCIT), 4 explored both sublingual and subcutaneous immunotherapy, and 3 investigated intralymphatic immunotherapy. The outcomes of these meta-analyses indicated a reduction in medication scores in 20 cases and a decrease in symptom scores in 23 cases. Additionally, six studies reported on changes in IgE levels, seven studies focused on IgG4, four studies examined FEV1 (forced expiratory volume in 1 s), and eight studies reported on symptom and medication scores. Furthermore, 11 studies reported on differences in adverse reactions.

CONCLUSION

The results of our meta-analysis suggest that specific immunotherapy, while associated with some adverse effects, effectively reduces the symptoms of asthma and rhinitis. Therefore, we recommend its use in the treatment of respiratory allergies.

Allergen sensitization study in Dongying, China: An epidemiological study

BACKGROUND

To explore the relationship between specific immunoglobulin E levels in response to prevalent pollen and food allergens among patients suffering from localized allergic diseases in the Dongying area of China, and to analyze the interconnectivity among these factors.

METHODS

This research encompassed allergic patients who visited the Allergy Department of Shengli Oilfield Central Hospital from January 2022 to January 2023. We examined the specific immunoglobulin E levels in the blood of 230 patients utilizing the Fobock platform provided by Jiangsu Haoeubo Company. Statistical analysis was conducted with SPSS 25.0 statistical software. The chi-square test evaluated the relevance of differences in gender and age. A value of P < .05 was considered statistically significant.

RESULTS

In this study, eggs emerged as the allergen with the highest number of sensitized individuals, closely followed by dust mite. Conversely, the least sensitized allergen was the cypress tree, closely followed by mango. Notably, male patients exhibited higher sensitivities to cottonwood (P < .05) and egg (P < .001) compared to female patients. Children aged 0 to 10 years showed increased sensitivity to variety of allergens. A significant correlation was observed among different allergens. The top ten allergen pairs with the highest correlation included Birch Tree and Cottonwood (0.88, P < .001), Cottonwood and Pine Tree (0.86, P < .001), Birch Tree and Pine Tree (0.84, P < .001), Pine Tree and Paulownia (0.81, P < .001), Dust Mite and House Dust Mite (0.76, P < .001), Birch Tree and Paulownia (0.73, P < .001), Cashew and Pistachio (0.71, P < .001), Apple and Hazelnut (0.71, P < .001), Cottonwood and Paulownia (0.71, P < .001), and Pine Tree and Ordinary Ragweed (0.70, P < .001).

CONCLUSION

This research sheds light on the patterns of allergen sensitization in Dongying, Shandong, highlighting that egg is the most prevalent sensitizing allergen. A notably high correlation was observed between Birch Tree and Cottonwood. This study enhanced the understanding of allergic diseases, explored the causes and mechanisms of allergies, strengthened the management of allergic diseases. Furthermore, it offers valuable insights for the clinical diagnosis and prevention of allergic diseases.

A, Hussain SM, Viswanad V, Nasr MH, Sahu RK, Khan J. Modulation of immune response by nanoparticle-based immunotherapy against food allergens

The increasing prevalence of food allergies worldwide and the subsequent life-threatening anaphylactic reactions often have sparse treatment options, providing only symptomatic relief. Great strides have been made in research and in clinics in recent years to offer novel therapies for the treatment of allergic disorders. However, current allergen immunotherapy has its own shortcomings in terms of long-term efficacy and safety, due to the local side effects and the possibility of anaphylaxis. Allergen-specific immunotherapy is an established therapy in treating allergic asthma, allergic rhinitis, and allergic conjunctivitis. It acts through the downregulation of T cell, and IgE-mediated reactions, as well as desensitization, a process of food tolerance without any allergic events. This would result in a protective reaction that lasts for approximately 3 years, even after the withdrawal of therapy. Furthermore, allergen-specific immunotherapy also exploits several routes such as oral, sublingual, and epicutaneous immunotherapy. As the safety and efficacy of allergen immunotherapy are still under research, the exploration of newer routes such as intra-lymphatic immunotherapy would address unfulfilled needs. In addition, the existence of nanoparticles can be exploited immensely in allergen immunotherapy, which would lead to safer and efficacious therapy. This manuscript highlights a novel drug delivery method for allergen-specific immunotherapy that involves the administration of specific allergens to the patients in gradual increasing doses, to induce desensitization and tolerance, as well as emphasizing different routes of administration, mechanism, and the application of nanoparticles in allergen-specific immunotherapy.

Clinical aspects of sublingual immunotherapy tablets and drops

BACKGROUND

Sublingual immunotherapy (SLIT) is administered via tablets (SLIT-T) or liquid drops (SLIT-D). In North America, currently 4 SLIT-T formulations are approved by the US Food and Drug Administration for allergy immunotherapy, and SLIT-D is an off-label use of subcutaneous immunotherapy (SCIT) extracts.

OBJECTIVE

To compare and contrast aspects of SLIT-T and SLIT-D, including physical characteristics, mechanism of action, dosing, efficacy, safety, adherence, and cost.

DATA SOURCES

PubMed literature review (no limits), product prescribing information, and manufacturer websites.

STUDY SELECTIONS

Publications related to physical characteristics, mechanism of action, dosing, efficacy, safety, and adherence.

RESULTS

Published evidence indicates that tablet and drop formulations differ in regard to physical characteristics, dosing, and strength of evidence for efficacy. Whether there are any differences in absorption and mechanism of action between the 2 formulations is currently unknown. Optimal dosing, efficacy, and safety have been established for SLIT-T. In contrast, in North America there is little support for efficacy of SLIT-D from randomized double-blind, placebo-controlled trials, and dose ranges have not been appropriately evaluated. SLIT-T treats a single allergen, whereas in the United States SLIT-D often contains multiple allergens to treat polysensitization. The safety profiles of SLIT-T and SLIT-D appear similar, and both formulations are considered safer than SCIT.

CONCLUSION

Professional guidelines should make a clear distinction between SLIT-T and SLIT-D in their recommendations to minimize confusion with the umbrella term SLIT.

Component-resolved evaluation of the content of major allergens in therapeutic extracts for specific immunotherapy of honeybee venom allergy

Allergen-specific immunotherapy is the only curative treatment of honeybee venom (HBV) allergy, which is able to protect against further anaphylactic sting reactions. Recent analyses on a molecular level have demonstrated that HBV represents a complex allergen source that contains more relevant major allergens than formerly anticipated. Moreover, allergic patients show very diverse sensitization profiles with the different allergens. HBV-specific immunotherapy is conducted with HBV extracts which are derived from pure venom. The allergen content of these therapeutic extracts might differ due to natural variations of the source material or different down-stream processing strategies of the manufacturers. Since variations of the allergen content of therapeutic HBV extracts might be associated with therapeutic failure, we adressed the component-resolved allergen composition of different therapeutic grade HBV extracts which are approved for immunotherapy in numerous countries. The extracts were analyzed for their content of the major allergens Api m 1, Api m 2, Api m 3, Api m 5 and Api m 10. Using allergen-specific antibodies we were able to demonstrate the underrepresentation of relevant major allergens such as Api m 3, Api m 5 and Api m 10 in particular therapeutic extracts. Taken together, standardization of therapeutic extracts by determination of the total allergenic potency might imply the intrinsic pitfall of losing information about particular major allergens. Moreover, the variable allergen composition of different therapeutic HBV extracts might have an impact on therapy outcome and the clinical management of HBV-allergic patients with specific IgE to particular allergens.

Comparative analysis of cluster versus conventional immunotherapy in patients with allergic rhinitis

The present study aimed to compare the efficacy and safety of subcutaneous immunotherapy with Dermatophagoides pteronyssinus standardized extract administered in conventional and cluster immunotherapy regiments for patients with persistent allergic rhinitis. A total of 60 patients with moderate to severe allergic rhinitis caused by dust mites were treated for 1 year with either conventional immunotherapy (n=30) or cluster immunotherapy (n=30). Nasal conjunctival symptoms and signs were assessed to evaluate the clinical efficacy of the two regimens, and the incidence of local and systemic adverse reactions were also evaluated. The findings demonstrated that the cluster regimen reduced the duration between the initial and maintenance dose by >60%, and resulted in a significant improvement, as compared with the conventional regimen, after 6 weeks of observation (P<0.05). However, the incidence of local and systemic adverse reactions in the cluster regimen during the dose accumulation phase and the dose maintenance phase was not significantly different, as compared with the conventional immunotherapy regimen. These results suggest that cluster immunotherapy is efficacious and safe to treat patients who are clinically sensitive to dust mites.

Safety and efficacy of rush allergen-specific immunotherapy in Chinese allergic rhinitis patients

The purpose of this prospective, open-IV clinical trial was to assess the safety and efficacy differences between Rush immunotherapy (RIT) and conventional immunotherapy in Chinese allergic rhinitis (AR) patients. The trial involved 174 patients with AR. They were divided into two groups according to their preference of therapy: RIT or conventional immunotherapy. A total of 162 patients completed a 1-year treatment course. For safety and effectiveness evaluation, the local and systemic adverse reactions were recorded throughout the initial phase of both groups. Weeks 0, 2, 5, and 17 were set as observation time points for immunoglobulin G (IgG) and IgG4. Besides that, another observation time point (Week 11) was added in for a visual analog scale (VAS) and a weekly drug dosage scale. In the RIT group, systemic adverse events of AR were similar to those of the conventional therapy group. LTB4 was descended. The VAS of the RIT group did not show a downward trend clearly, instead Week 5 was higher compared with Week 0. The weekly drug dosage scale did not indicate a significant decline, but there was a clear rise in IgG4 in the RIT group. The safety and efficacy of RIT for AR is positive, but further study is needed for improvement.

Subdominant Outer Membrane Antigens in Anaplasma marginale: Conservation, Antigenicity, and Protective Capacity Using Recombinant Protein

Anaplasma marginale is a tick-borne rickettsial pathogen of cattle with a worldwide distribution. Currently a safe and efficacious vaccine is unavailable. Outer membrane protein (OMP) extracts or a defined surface protein complex reproducibly induce protective immunity. However, there are several knowledge gaps limiting progress in vaccine development. First, are these OMPs conserved among the diversity of A. marginale strains circulating in endemic regions? Second, are the most highly conserved outer membrane proteins in the immunogens recognized by immunized and protected animals? Lastly, can this subset of OMPs recognized by antibody from protected vaccinates and conserved among strains recapitulate the protection of outer membrane vaccines? To address the first goal, genes encoding OMPs AM202, AM368, AM854, AM936, AM1041, and AM1096, major subdominant components of the outer membrane, were cloned and sequenced from geographically diverse strains and isolates. AM202, AM936, AM854, and AM1096 share 99.9 to 100% amino acid identity. AM1041 has 97.1 to 100% and AM368 has 98.3 to 99.9% amino acid identity. While all four of the most highly conserved OMPs were recognized by IgG from animals immunized with outer membranes, linked surface protein complexes, or unlinked surface protein complexes and shown to be protected from challenge, the highest titers and consistent recognition among vaccinates were to AM854 and AM936. Consequently, animals were immunized with recombinant AM854 and AM936 and challenged. Recombinant vaccinates and purified outer membrane vaccinates had similar IgG and IgG2 responses to both proteins. However, the recombinant vaccinates developed higher bacteremia after challenge as compared to adjuvant-only controls and outer membrane vaccinates. These results provide the first evidence that vaccination with specific antigens may exacerbate disease. Progressing from the protective capacity of outer membrane formulations to recombinant vaccines requires testing of additional antigens, optimization of the vaccine formulation and a better understanding of the protective immune response.

Japanese Society of Allergology task force report on standardization of house dust mite allergen vaccines - secondary publication

BACKGROUND

In the 1990s, the Japanese Society of Allergology (JSA) standardized Japanese cedar pollen allergen vaccines. In the present study, the task force for house dust mite (HDM) allergen standardization of the Committee for Allergens and Immunotherapy of JSA reports the standardization of HDM allergen vaccines in Japan.

METHODS

In vivo allergenic potency was determined by intradermal testing of 51 Japanese adults with positive serum specific IgE to HDM allergens. In vitro total IgE binding potency was analyzed by competition ELISA using a pooled serum, with sera obtained from 10 allergic patients. The amounts of HDM group 1 (Der 1) and group 2 major allergens in eight HDM allergen extracts were measured by sandwich ELISAs. Correlation between the in vitro total IgE binding potency and major allergen levels was analyzed.

RESULTS

We selected a JSA reference HDM extract and determined its in vivo allergenic potency. The in vitro total IgE binding potency significantly correlated with Der 1 content, group 2 allergen content, and their combined amount, indicating that measurement of major allergen contents can be used as a surrogate in vitro assay.

CONCLUSIONS

The task force determined the in vivo allergenic potency (100,000 JAU/ml) and Der 1 content (38.5 μg/ml) of the JSA reference HDM extract, selected the measurement of Der 1 content as the surrogate in vitro assay, and decided that manufacturers can label a HDM allergen extract as having a titer of 100,000 JAU/ml if it contains 22.2-66.7 μg/ml of Der 1.

Multiple grass mixes as opposed to single grasses for allergen immunotherapy in allergic rhinitis

Grass pollen allergy affects approximately 40% of allergic patients. Subcutaneous allergen immunotherapy (SCIT) is the only allergen-specific and disease-modifying treatment available. Currently available therapeutic vaccines for the treatment of grass pollen allergy are based on natural grass pollen extracts which are either made from pollen of one cross-reactive grass species or from several related grass species. Clinical studies have shown that SCIT performed with timothy grass pollen extract is effective for the treatment of grass pollen allergy. Moreover, it has been demonstrated that recombinant timothy grass pollen allergens contain the majority of relevant epitopes and can be used for SCIT in clinical trials. However, recent in vitro studies have suggested that mixes consisting of allergen extracts from several related grass species may have advantages for SCIT over single allergen extracts. Here, we review current knowledge regarding the disease-relevant allergens in grass pollen allergy, available clinical studies comparing SCIT with allergen extracts from timothy grass or from mixes of several related grass species of the Pooideae subfamily, in vitro cross-reactivity studies performed with natural allergen extracts and recombinant allergens and SCIT studies performed with recombinant timothy grass pollen allergens. In vitro and clinical studies performed with natural allergen extracts reveal no relevant advantages of using multiple grass mixes as opposed to single grass pollen extracts. Several studies analysing the molecular composition of natural allergen extracts and the molecular profile of patients' immune responses after SCIT with allergen extracts indicate that the major limitation for the production of a high quality grass pollen vaccine resides in intrinsic features of natural allergen extracts which can only be overcome with recombinant allergen-based technologies.

Multiallergen-specific immunotherapy in polysensitized patients: where are we?

Allergen-specific immunotherapy administered by the subcutaneous route was introduced a century ago and has been shown to be effective in the management of allergic rhinitis and asthma. More recently, the sublingual administration of allergen extracts has become popular, especially in European countries, and has also demonstrated efficacy in respiratory allergic diseases. Both modes of allergen administration during immunotherapy have been shown not only to reduce symptoms and the need for medication, but also to prevent the development of additional sensitivities in monosensitized patients, as well as asthma development in patients with allergic rhinitis, with a long-lasting effect after the completion of several years of treatment. Almost all of the well-designed and double-blinded, placebo-controlled studies evaluated treatment with single-allergen extracts. Therefore, most meta-analyses published to date evaluated immunotherapy with single allergen or extracts containing several cross-reactive allergens. As a result, in general, multiallergen immunotherapy in polysensitized patients (mixture of noncross-reactive allergens) is not recommended owing to lack of evidence. Although some guidelines have recommended against the use of multiallergen mixtures, allergists commonly use mixtures to which the patient is sensitive with the rationale that effective immunotherapy should include all major sensitivities. Literature on this subject is scarce in spite of the widespread use worldwide. Here, this issue will be extensively discussed based on currently available literature and future perspectives will also be explored.

A survey of the prescription patterns of allergen immunotherapy in Korea

Purpose

Allergen immunotherapy (AIT) has been used as a curative and specific treatment of allergic diseases. However, no data on the prescription patterns of AIT in Korea is available. Therefore, we surveyed the prescription patterns of AIT by allergy specialists in Korea.

Methods

We emailed a questionnaire on AIT prescription patterns to the 690 members of the Korean Academy of Asthma, Allergy and Clinical Immunology with clinical practice experience. All returned answers were evaluated.

Results

The response rate was 21.0%. Only 69.0% of the respondents performed AIT in practice. Hindrance factors for performing AIT in the practice included a lack of facilities (21%), lack of practical experience during their subspecialty or postgraduate educational training programs (15.8%), no need for AIT because of sufficient pharmacotherapy (14.5%), insufficient economic profits (14.5%), and risks for adverse reactions (13.2%). Ninety-two allergy specialists (82%) performed AIT subcutaneously subcutaneous immunotherapy (SCIT) and 20 allergy specialists (18%) performed it sublingually sublingual immunotherapy (SLIT). Only 8 specialists performed both SCIT and SLIT. The allergens used for SCIT were house dust mites (98.9%), pollens (72.8%), and animal dander (23.9%). SLIT was prescribed only for house dust mites. Twenty-eight physicians (30.4%) observed anaphylactic reactions during SCIT. Eight physicians (40.0%) who prescribed SLIT observed adverse reactions, including local reactions, but none of them observed anaphylactic reactions.

Conclusions

In this survey, 69.0% of the respondents performed AIT in clinical practice. SCIT prescription is more popular than SLIT. The Lack of facilities and clinical education is a critical barrier to performing AIT. Therefore, proper clinical education of AIT is necessary for Korean allergists.

Molecular approaches to allergen standardization

Molecular approaches to allergen standardization include the development of purified natural or recombinant allergen standards whose structural and allergenic properties have been validated, in tandem with certified immunoassays for allergen measurement. Purified allergens can be used individually or incorporated into multiple allergen standards. Multicenter international collaborative studies are required to validate candidate allergen standards and immunoassays, as a prelude to being approved by regulatory agencies. Mass spectrometry is a sophisticated and powerful proteomics tool that is being developed for allergen analysis. Recent results using pollen allergens show that mass spectrometry can identify and measure specific allergens in a complex mixture and can provide precise information of the variability of natural allergen extracts. In future, the combined use of immunoassays and mass spectrometry will provide complete standardization of allergenic products. Molecular standardization will form the basis of new allergy diagnostics and therapeutics, as well as assessment of environmental exposure, and will improve the quality of treatment options for allergic patients.

New routes for allergen immunotherapy

IgE-mediated allergy is a highly prevalent disease in the industrialized world. Allergen-specific immunotherapy (SIT) should be the preferred treatment, as it has long lasting protective effects and can stop the progression of the disease. However, few allergic patients choose to undergo SIT, due to the long treatment time and potential allergic adverse events. Since the beneficial effects of SIT are mediated by antigen presenting cells inducing Th1, Treg and antibody responses, whereas the adverse events are caused by mast cells and basophils, the therapeutic window of SIT may be widened by targeting tissues rich in antigen presenting cells. Lymph nodes and the epidermis contain high density of dendritic cells and low numbers of mast cells and basophils. The epidermis has the added benefit of not being vascularised thereby reducing the chances of anaphylactic shock due to leakage of allergen. Hence, both these tissues represent highly promising routes for SIT and are the focus of discussion in this review.

Efficacy of sublingual immunotherapy versus subcutaneous injection immunotherapy in allergic patients

While it is generally accepted that Subcutaneous Injection Immunotherapy (SCIT) and Sublingual Immunotherapy (SLIT) are both efficacious, there is not yet a significant amount of information regarding their comparative efficacy. In this paper, we performed a retrospective chart review and compared treatment results in two groups of patients (both with nasal allergies with or without asthma) that were treated either with SCIT or SLIT. Both treatment modalities were found to be of similar efficacy.

Changes in Peak Flow value during immunotherapy administration

Nasal allergies are prevalent affecting a large percentage of the population. Not only the upper respiratory tract but the whole body is involved. Allergies produce morbidity (and even occasional mortality) as they can lead to asthma development, and increased number of accidents. Immunotherapy results can be evaluated by following symptom scores, medication use, and objective measurements. Using a Peak Flow Meter (PFM) to evaluate immunotherapy results, it became evident that patients with and without asthma exhibited an improvement in the Peak Flow (PF) value, suggesting that lower airway involvement in allergic patients could be more prevalent than assumed. A consecutive chart review was performed including patients of any age with nasal allergies (with or without asthma) treated with immunotherapy for at least 6 months that had at least 2 complete evaluations. When immunotherapy was successful, most patients exhibited an increase in the PF value regardless of asthma status. A very significant finding was that most allergy sufferers may have lower airway inflammation. The use of the PF value to assess immunotherapy results and the potential failure to diagnose asthma in allergy sufferers are discussed. A better diagnosis of lower airway inflammation could be substantial in the management of these patients.

A multi-allergen standard for the calibration of immunoassays: CREATE principles applied to eight purified allergens

BACKGROUND

Allergen measurements are widely used for environmental exposure assessments and for determining the potency of allergen vaccines, yet few purified allergen standards have been developed. The aim of the study was to develop a single standard containing multiple purified allergens that could be used in enzyme immunoassays and in multiplex arrays for the standardization of allergen measurements.

METHODS

Eight purified allergens were formulated into a single multi-allergen, or 'universal', standard based on amino acid analysis. Dose-response curves were compared with previous individual ELISA standards and allergen measurements of house dust extracts to obtain correction factors. Measured allergen concentrations were also modeled using linear regression, and the predictive accuracy was determined.

RESULTS

Parallel dose-response curves were obtained between the universal allergen standard and the individual ELISA standards, with close agreement between curves for 5/8 allergens. Quantitative differences of greater than twofold were observed for Fel d 1, Can f 1, and Der f 1, which were confirmed by the analysis of house dust extracts. Correction factors were developed that allowed ELISA data to be expressed in terms of the universal standard. Linear regression data confirmed the predictive accuracy of the universal standard.

CONCLUSION

This study shows that a single standard of eight purified allergens can be used to compare allergen measurements by immunoassay. This approach will improve the continuity of environmental exposure assessments and provide improved standardization of allergy diagnostics and vaccines used for immunotherapy.

Quality of life improvement with sublingual immunotherapy: a prospective study of efficacy

Due to its excellent safety profile, ease of administration, and economic considerations, sublingual immunotherapy (SLIT) is becoming a preferred form of allergen specific immunotherapy. The efficacy of SLIT is still debated. The purpose of this act of practice trial is to evaluate quality of life outcomes in patients treated with SLIT. Fifty one patients with allergic rhinoconjunctivitis demonstrated by skin testing completed the Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ) at initiation, at four months and at 10-12 months of SLIT. Significant improvement (P < 0.05) on six of seven domain categories of the RQLQ questionnaire was noted. Total RQLQ scores also showed significant improvement. This study supports SLIT as a modality effective in controlling allergic symptoms.

Specific immunotherapy in children: the evidence

Specific immunotherapy (SIT) is the only treatment able to not only act on the symptoms of allergy but also act on the causes. At present, SIT may be administered in two forms: subcutaneous (SCIT) and sublingual immunotherapy (SLIT). SCIT represents the standard modality of treatment while SLIT has recently been introduced into clinical practice and today represents an accepted alternative to SCIT. The main advantages of SIT that are lacking with drug treatment are long-lasting clinical effects and alteration of the natural course of the disease. This prevents the new onset of asthma in patients with allergic rhinitis and the onset of new sensitizations. The mechanism of action of both routes is similar; they modify peripheral and mucosal Th2-responses into a prevalent Th1-polarization with subsequent reduction of the allergic inflammatory reaction. Both have long-term effects for years after they have been discontinued, although for SLIT these evidences are insufficient. To date several guidelines have defined indications, controindications, side-effects, and clinical aspect for SCIT and SLIT. New forms of immunotherapy, allergen products and approaches to food allergy and atopic eczema represents the future of SIT.

Prevention of allergic asthma by vaccination with transgenic rice seed expressing mite allergen: induction of allergen-specific oral tolerance without bystander suppression

This study tested the feasibility of oral immunotherapy for bronchial asthma using a newly developed subunit vaccine in which a fragment (p45-145) of mite allergen (Der p 1) containing immunodominant human and mouse T cell epitopes was encapsulated in endoplasmic reticulum-derived protein bodies of transgenic (Tg) rice seed. Allergen-specific serum immunoglobulin responses, T cell proliferation, Th1/Th2 cytokine production, airway inflammatory cell infiltration, bronchial hyper-responsiveness (BHR) and lung histology were investigated in allergen-immunized and -challenged mice. Prophylactic oral vaccination with the Tg rice seeds clearly reduced the serum levels of allergen-specific IgE and IgG. Allergen-induced CD4(+) T cell proliferation and production of Th2 cytokines in vitro, infiltration of eosinophils, neutrophils and mononuclear cells into the airways and BHR were also inhibited by oral vaccination. The effects of the vaccine were antigen-specific immune response because the levels of specific IgE and IgG in mice immunized with Der f 2 or ovalbumin were not significantly suppressed by oral vaccination with the Der p 1 expressing Tg rice. Thus, the vaccine does not induce nonspecific bystander suppression, which has been a problem with many oral tolerance regimens. These results suggest that our novel vaccine strategy is a promising approach for allergen-specific oral immunotherapy against allergic diseases including bronchial asthma.

Strategies of mucosal immunotherapy for allergic diseases

Incidences of allergic disease have recently increased worldwide. Allergen-specific immunotherapy (SIT) has long been a controversial treatment for allergic diseases. Although beneficial effects on clinically relevant outcomes have been demonstrated in clinical trials by subcutaneous immunotherapy (SCIT), there remains a risk of severe and sometimes fatal anaphylaxis. Mucosal immunotherapy is one advantageous choice because of its non-injection routes of administration and lower side-effect profile. This study reviews recent progress in mucosal immunotherapy for allergic diseases. Administration routes, antigen quality and quantity, and adjuvants used are major considerations in this field. Also, direct uses of unique probiotics, or specific cytokines, have been discussed. Furthermore, some researchers have reported new therapeutic ideas that combine two or more strategies. The most important strategy for development of mucosal therapies for allergic diseases is the improvement of antigen formulation, which includes continuous searching for efficient adjuvants, collecting more information about dominant T-cell epitopes of allergens, and having the proper combination of each. In clinics, when compared to other mucosal routes, sublingual immunotherapy (SLIT) is a preferred choice for therapeutic administration, although local and systemic side effects have been reported. Additionally, not every allergen has the same beneficial effect. Further studies are needed to determine the benefits of mucosal immunotherapy for different allergic diseases after comparison of the different administration routes in children and adults. Data collected from large, well-designed, double-blind, placebo-controlled, and randomized trials, with post-treatment follow-up, can provide robust substantiation of current evidence.

IgG antibodies produced during subcutaneous allergen immunotherapy mediate inhibition of basophil activation via a mechanism involving both FcgammaRIIA and FcgammaRIIB

The majority of human subjects who receive subcutaneous allergen immunotherapy (IT) develop decreased sensitivity to their allergens. Multiple factors may explain the efficacy of IT, some evidence support a role for allergen specific IgG antibodies. There is controversy whether such antibodies act by blocking allergen binding to IgE or initiation of active inhibitory signaling through low affinity IgG receptors (FcgammaRIIB) on mast cells and basophils. In this study, we addressed this question using peripheral blood from cat non-allergic, cat allergic, and immunotherapy-treated cat allergic subjects. Blood from subjects who received IT contain IgG antibodies that mediate inhibition of basophil activation by a mechanism that is blocked by antibodies specific for the inhibitory IgG receptor FcgammaRIIB. Surprisingly, inhibition was also blocked by aglycosylated, putatively non-FcR binding, antibodies that are specific for the FcgammaRIIA, suggesting a contribution of this receptor to the observed effect. Consistent with a cooperative effect, ex vivo basophils were found to express both IgG receptors. In other studies we found that basophils from subjects who were both chronically exposed to allergen and were producing both cat allergen specific IgE and IgG, are hyporesponsive to allergen. These studies confirm that IgG antibodies produced during IT act primarily by stimulation of inhibitory signaling, and suggest that FcgammaRIIA and FcgammaRIIB function cooperatively in activation of inhibitory signaling circuit. We suggest that under normal physiologic conditions in which only a small proportion of FcepsilonRI are occupied by IgE of a single allergen specificity, FcgammaRIIA co-aggregation may, by providing activated Lyn, be required to fuel activation of inhibitory FcgammaRIIB function.

Safety of a depigmented, polymerized vaccine for the treatment of allergic rhinoconjunctivitis and allergic asthma

BACKGROUND

Clinical efficacy of specific immunotherapy (SIT) with depigmented, polymerized allergen extracts is well documented in placebo-controlled trials, and safety data are encouraging although further data are required.

METHODS

We enrolled 768 patients (51% men; mean age, 31 years) in this prospective multicenter study on safety and clinical effects of Depigoid (Laboratorios LETI, S.L., Madrid, Spain). Immunotherapy consisted of four injections of increasing doses of Depigoid at weekly intervals followed by monthly maintenance injections. All adverse events were documented. Moreover, nose, eye, and lung symptoms were assessed at baseline after 3 and 6 months. Results were compared with the scores of the preceding season.

RESULTS

Rates for local and systemic reactions that might possibly be related to the study medication were 2.36 and 4.56/1000 injections, respectively. With 5923 injections given, 14 local reactions were reported (5 patients), and 27 systemic reactions were reported, including 20 of grade 1 (6 patients) and 7 of grade 2 (4 patients). The best safety profile was seen for patients vaccinated against house-dust mites. Reductions in nose, eye, and lung symptoms as well as in concomitant medication compared with either the preceding season (pollen-sensitized patients) or the baseline (house-dust mite-sensitized patients) were observed at the end of study.

CONCLUSION

In this large multicenter study on 768 patients with allergic rhinoconjunctivitis and allergic asthma under daily practice conditions SIT with Depigoid was well tolerated with low rates of local and systemic reactions. Furthermore, SIT resulted in considerable reductions in symptoms and concomitant medication.

Desensitization of ovalbumin-sensitized mice by repeated co-administrations of di-(2-ethylhexyl) phthalate and ovalbumin

Background

The plasticizer di-(2-ethylhexyl) phthalate (DEHP) has been shown to stimulate a non-allergy related immune response with increased levels of IgG1 and IgG2a, but not IgE, after co-administration with the model allergen ovalbumin (OVA) in mice. In mice, decreased IgG1 and increased IgG2a have been associated with the development of mucosal tolerance towards inhaled allergens. As DEHP selectively promote formations of IgG1 and IgG2a without stimulating the IgE response, it was hypothesized that DEHP may suppress an established IgE mediated allergic response. Mice pre-sensitised to OVA were repeatedly co-exposed to DEHP and OVA and the effects were evaluated on the levels of OVA-specific antibodies, ex vivo cytokine levels and the degree of lung inflammation after challenge with an OVA aerosol.

Findings

Compared to the OVA-sensitised control mice, multiple co-exposures to DEHP+OVA reduced the IgG1 level and reduced the IgE/IgG2a ratio. This suggests that DEHP may attenuate allergic sensitisation, as the IgE/IgG2a ratio has been shown to correlate with the degree of anaphylaxis. Nevertheless, no effect of DEHP exposures was seen on inflammatory cells in bronchoalveolar lavage fluid and on cytokine levels in spleen cell culture.

Conclusion

Data from humane and murine studies suggest that DEHP may attenuate the allergic response. More studies are necessary in order to assess the size of this effect and to rule out the underlying mechanism.

Undertreatment of allergy: exploring the utility of sublingual immunotherapy

Allergic syndromes are highly prevalent and are comprised of a wide variety of clinical problems, including rhinitis, conjunctivitis, atopic dermatitis and urticaria, asthma, and food allergies. Numerous studies have shown that allergic syndromes are both underdiagnosed and undertreated. This is related to many factors, including trivialization of allergic conditions by physicians and patients, failure to adhere to diagnostic and treatment guidelines, and dissatisfaction with conventional pharmacologic treatments. Immunotherapy involves the administration of allergen extracts in an attempt to induce immunologic tolerance and has been used for the treatment of allergic syndromes and the prevention of long-term complications. Conventional subcutaneous immunotherapy is effective but is also associated with a risk of serious adverse events, requires administration by a trained health care professional, and is contraindicated in certain populations. By contrast, sublingual immunotherapy has been used extensively in Europe and possesses most of the benefits of subcutaneous immunotherapy along with increased safety, tolerability, and convenience. This narrative review explores data from selected clinical studies and concludes that sublingual immunotherapy may be well suited to fill the gap posed by the undertreatment of allergic syndromes in the United States.

Targeting allergen to Fc gammaRI: a strategy to treat allergic disease?

PURPOSE OF REVIEW

Targeting allergens to surface receptors on antigen presenting cells may provide a therapeutic strategy for allergic disease. This article discusses the immunomodulatory capacity of a molecule (H22-Fel d 1), which targets the major cat allergen, Fel d 1, to the high affinity IgG receptor, Fc gammaRI, on human dendritic cells.

RECENT FINDINGS

The fusion protein, H22-Fel d 1, induced a semi-mature phenotype in dendritic cells characterized by production of inflammatory cytokines with no change in surface markers, suggesting tolerogenic capacity. At the T-cell level, H22-Fel d 1 stimulated increased proliferation coupled with amplification of T cells expressing IL-5 and IL-10. Further analysis revealed induction of diverse T cell subtypes characteristic of Th0, regulatory Th1 and regulatory Th2 cells. Notably, this effect was restricted to T cells isolated from cat-allergic patients. Despite the increase in IL-5-expressing T cells, responses induced by H22-Fel d 1 appeared to be regulated by IL-10. Comparison with nonreceptor-targeted allergens from cat and house dust mite confirmed that qualitative T-cell changes induced by H22-Fel d 1 were unique.

SUMMARY

H22-Fel d 1 induces a novel variation of the Th2 response, which incorporates elements of a protective T-cell response. Exploiting Fc gammaRI-mediated pathways for allergen delivery may offer a new approach for treatment.

Summary of the 2008 National Institute of Allergy and Infectious Diseases-US Food and Drug Administration Workshop on Food Allergy Clinical Trial Design

This article summarizes the proceedings of a 2008 Workshop on Food Allergy Clinical Trials Design co-organized by the National Institute of Allergy and Infectious Diseases and the US Food and Drug Administration. The use of food allergens both as therapy and for oral food challenges is associated with a risk of anaphylaxis. Investigators are strongly encouraged to address regulatory considerations by discussing proposed studies with the US Food and Drug Administration. Food allergen administration through the oral or sublingual routes might be less risky than through the subcutaneous route, but this hypothesis has not been proved, and subjects with food allergy might still be at high risk of allergic reactions to such allergen administration. Two distinct mechanisms might lead to beneficial clinical outcomes: desensitization (reversible when food allergen therapy is stopped) and tolerance (persistent benefit even after allergen therapy is stopped). There are important clinical distinctions between desensitization and tolerance. The efficacy of a therapy for food allergy can be evaluated by assessing changes in the dose response to double-blind, placebo-controlled oral food challenges before and after therapy and also by assessing changes in the number of allergic episodes during a longitudinal natural history/exposure study; both approaches have strengths and limitations.

Sublingual immunotherapy for children: Are we there yet? Defining its role in clinical practice

Immunotherapy in various forms has been used to treat allergic disorders since the early 19th century. Subcutaneous immunotherapy is now well established for the treatment of insect anaphylaxis and allergic rhinitis. The route of administration and possibility of severe adverse reactions to subcutaneous immunotherapy make sublingual immunotherapy an appealing alternative, especially for the paediatric patient. This form of immunotherapy has been increasingly used in Europe, and over the past decade several meta analyses have attempted to provide evidence for its efficacy in the treatment of seasonal and perennial allergic rhinitis and in asthma, both in the adult and paediatric population. Several trials have also shown a potential immunomodulatory effect of sublingual immunotherapy, with evidence of a reduction in the progression from allergic rhinitis to asthma and reduced new aeroallergen sensitisation. This review will give an overview of the current evidence for sublingual immunotherapy in the paediatric population.

Article Commentary: Sublingual immunotherapy for inhalant allergy: Cautious optimism

Sublingual immunotherapy (SLIT) is being utilized with increasing frequency in both Europe and the United States. While the data with commercially-prepared single-antigen SLIT appear promising, there has been an extrapolation of these data beyond the scope of the well-controlled clinical trials that have been published in the literature. In this environment of enthusiasm, it is prudent to examine variables that are relevant in evaluating how SLIT can be incorporated into American allergy practice on a broader scale. This commentary will discuss five areas of potential concern in moving toward wider implementation of SLIT: (1) patient selection for treatment; (2) pattern of sensitization; (3) dosing, preparation, and delivery; (4) safety concerns; and (5) cost of therapy. Additional research is necessary to adequately address these important issues to ensure that SLIT will offer a safe, well-tolerated, and effective treatment for Americans with inhalant allergy.

Mediator release assay for assessment of biological potency of German cockroach allergen extracts

BACKGROUND

Cockroach is an important allergen in inner-city asthma. The diagnosis and treatment of cockroach allergy has been impeded by the lack of standardized cockroach extracts.

OBJECTIVE

We investigated the utility of a mediator release assay based on rat basophil leukemia (RBL) cells for comparing the potency of German cockroach extracts.

METHODS

RBL cells (line 2H3) transfected with human FcepsilonRI were passively sensitized with sera from subjects with cockroach allergy and stimulated with serial dilutions of 3 commercial cockroach extracts (1:10 weight/volume). In addition, the in-house prepared extract was tested in separate experiments with pooled sera that produced optimal performance in the RBL assay. N-hexosaminidase release (NHR) was used as a marker of RBL cell degranulation and was examined in relation to the intradermal skin test (ID(50)EAL) and serum cockroach-specific and total IgE levels.

RESULTS

The median cockroach-specific IgE concentration in 60 subjects was 0.72 kU(A)/L (interquartile range, 0.35-2.97 kU(A)/L); 19 sera (responders) produced a minimum 10% NHR to more than 1 extract. Responders had higher median cockroach-specific IgE (7.4 vs 1.0 kU(A)/L) and total IgE (429 vs 300 kU/L) levels than nonresponders. Ranking of extract potency was consistent between the mediator release assay and the ID(50)EAL. For the in-house prepared cockroach extract, the dose-response curves were shifted according to the concentration of the extract. NHR was reproducible between different experiments by using pooled sera.

CONCLUSION

The mediator release assay measures biologic potency and correlates with the ID(50)EAL. It should be further evaluated to determine whether it could be used to replace intradermal skin test titration for assessing the potency of cockroach extract.

Clinical and Immunological Correlates of Pre-Co-Seasonal Sublingual Immunotherapy with Birch Monomeric Allergoid in Patients with Allergic Rhinoconjunctivitis

Sublingual immunotherapy is safe and efficacious in the treatment of patients with allergic rhinitis. The clinical and biological efficacy of modified allergens (allergoids) has not been fully clarified. We investigated in birch allergic patients the effect of a pre-co-seasonal sublingual immunotherapy regimen with a modified allergen extract on clinical parameters and on T cell proliferation and regulatory cytokine production (IL-10, TGF-beta). We found that during the birch pollen season symptoms and drug usage scores were 30 and 40% improved, respectively, in treated versus control subjects (p<0.0001 for both comparisons) whereas well days were 23.5 (33%) versus 16.9 (23%) (p=0.0024), respectively. Bet v 1 allergen specific proliferation decreased (p = 0.0010), whereas IL-10 transcription increased (p = 0.0010) in treated, but not in control patients. Moreover, TGF-beta transcription was increased, although not significantly (p=0.066), following immunotherapy. Thus, sublingual immunotherapy with modified allergen in birch-allergic subjects was safe, clinically efficacious and associated with the reduction of allergen-specific proliferation and with the increased production of the IL-10 regulatory cytokine.

Specific immunotherapy for respiratory allergy: state of the art according to current meta-analyses

OBJECTIVE

To evaluate the efficacy of allergen specific immunotherapy in the treatment of allergic asthma and rhinitis as derived by the available meta-analyses.

DATA SOURCES

Electronic databases were searched up to April 30, 2008, for meta-analyses of randomized, placebo-controlled trials assessing specific immunotherapy in respiratory allergy. We looked for studies that evaluated effects on symptom scores and use of rescue medication.

STUDY SELECTION

If 2 or more reviews evaluated the same subject, we selected the study with the larger number of patients. We evaluated the quality of individual meta-analyses by following the recommendations of the Cochrane Collaboration and the QUOROM (Quality of Reporting of Meta-analyses) statement.

RESULTS

Seven of 13 meta-analyses met the inclusion criteria: 5 evaluating sublingual immunotherapy and 2 evaluating subcutaneous immunotherapy. All 7 meta-analyses reported a reduction in symptom and medication scores, although 1 sublingual immunotherapy meta-analysis did not find a significant size effect, probably because of the inclusion criteria. Heterogeneity was significant in all 7 included reviews, and standardized mean differences using the random-effects model were adopted.

CONCLUSIONS

According to evidence-based criteria, specific immunotherapy can be recommended for the treatment of respiratory allergy because of its efficacy in reducing asthma and rhinitis symptoms. Also, future methodological approaches that consider safety and costs should corroborate this positive evaluation.

Analysis of helper T cell responses to Cry j 1-derived peptides in patients with nasal allergy: candidate for peptide-based immunotherapy of Japanese cedar pollinosis

BACKGROUND

Allergen specific immunotherapy is highly effective, but adverse events may occur during treatment. Peptide-based immunotherapy has been proposed as one of new strategies for reduction of allergic adverse reactions. We examined the possibility of candidate peptides for the development of peptide-based immunotherapy for Japanese cedar pollinosis.

METHODS

Twelve Cry j 1-specific T-cell lines were established from peripheral blood mononuclear cells (PBMC) of 12 patients with Japanese cedar pollinosis. Using these T-cell lines, 37 Cry j 1-derived overlapping peptides were assessed for their proliferative responses and cytokine production.

RESULTS

Four peptides corresponding to the Cry j 1 sequence were able to induce proliferative responses to more than one T-cell line: p61-80 (3/12; 25.0%); p115-132 (2/12; 16.6%); p206-225 (4/12; 33.3%); and p337-353 (5/12; 41.7%). Furthermore, T-cell lines generated from 11 of 12 donors (91.7%) responded to at least one of these four peptides. On the other hand, the pattern of cytokine production from Cry j 1-specific T-cell lines varied. Moreover, cytokine production patterns by stimulation with Cry j 1 peptide did not reflect those by stimulation with Cry j 1 protein.

CONCLUSIONS

Our results suggest four Cry j 1-derived peptides (p61-80, p115-132, p206-225 and p337-353) may be considered to be the immunodominant T-cell epitopes of the Cry j 1 molecule, and can be useful for the design of peptide-based immunotherapy for the management of Japanese cedar pollinosis.

Asthma in childhood

Management decisions for pediatric asthma (in patients younger than 12 years of age) based on extrapolation from available evidence in adolescents and adults (age 12 years and older) is common but rarely appropriate. This article addresses the disparity in response between the two age groups, presents the available pediatric evidence, and highlights the important areas in which further research is required. Evidence-based recommendations for acute and interval management of pediatric asthma are provided.

Dendritic cells genetically engineered to express IL-10 induce long-lasting antigen-specific tolerance in experimental asthma

Dendritic cells (DCs) are professional APCs that have a unique capacity to initiate primary immune responses, including tolerogenic responses. We have genetically engineered bone marrow-derived DCs to express the immunosuppressive cytokine IL-10 and tested the ability of these cells to control experimental asthma. A single intratracheal injection of OVA-pulsed IL-10-transduced DCs (OVA-IL-10-DCs) to naive mice before OVA sensitization and challenge prevented all of the cardinal features of airway allergy, namely, eosinophilic airway inflammation, airway hyperreactivity, and production of mucus, Ag-specific Igs, and IL-4. OVA-IL-10-DCs also reversed established experimental asthma and had long-lasting and Ag-specific effects. We furthermore showed, by using IL-10-deficient mice, that host IL-10 is required for mediating the immunomodulatory effects of OVA-IL-10-DCs and demonstrated a significant increase in the percentage of OVA-specific CD4(+)CD25(+)Foxp3(+)IL-10(+) regulatory T cells in the mediastinal lymph nodes of OVA-IL-10-DC-injected mice. Finally, adoptive transfer of CD4(+) mediastinal lymph node T cells from mice injected with OVA-IL-10-DCs protected OVA-sensitized recipients from airway eosinophilia upon OVA provocation. Our study describes a promising strategy to induce long-lasting Ag-specific tolerance in airway allergy.

Allergen-related approaches to immunotherapy

Allergic diseases, including asthma, rhinitis and eczema, represent a major health burden worldwide. Mainstay treatments are allergen avoidance where feasible and pharmacotherapy for symptom relief. For selected patients, allergen-specific immunotherapy (SIT) offers the prospect of long lasting clinical efficacy. SIT involves the administration of allergen extract using a standardized regimen, usually subcutaneously or increasingly sublingually. However, application of this potentially curative treatment is restricted, largely due to the risk of serious adverse events, especially in asthmatics and for potent allergens such as peanut, seafood and latex. New insights into immunological mechanisms underlying effective SIT and molecular characterization of allergens and their recognition by the immune system suggest strategies for refinement of SIT. Selective targeting of allergen-specific T cells, especially regulatory T cells, is likely to be pivotal for efficacy. Recombinant allergens lacking IgE reactivity and small T cell epitope-based peptides are being trialled clinically with evidence of efficacy without serious IgE-mediated adverse reactions. Adjuvants, either co-administered or incorporated into a recombinant allergen vaccine to target tolerogenic dendritic cells may also increase efficacy. The safer sublingual route of allergen administration is attracting interest and different allergen forms may be optimal for inducing tolerance by this route. Defined allergen-derived molecules or peptides offer ease of standardization and, coupled with appropriate targeting of immunoregulatory mechanisms, will result in more widespread clinical use of SIT. Adjunct therapies such as anti-IgE antibody and corticosteroids may minimize the likelihood of adverse reactions in those with severe allergic disease who would most benefit from this treatment.

The European Union CREATE project: a model for international standardization of allergy diagnostics and vaccines

Allergen measurements are used extensively in the formulation of allergy diagnostics and vaccines, yet no purified international allergen standards are available for calibration purposes. The aims of the European Union CREATE project were to develop international standards with verifiable allergen content. Purified natural and recombinant allergens were analyzed by means of SDS-PAGE, mass spectrometry, circular dichroism spectra, and small-angle x-ray scattering. IgE reactivity was assessed by means of direct RAST, RAST inhibition, immunoblotting, and basophil histamine release with sera from 961 allergic patients. Three recombinant allergens, rBet v 1, rPhl p 5a, and rDer p 2, were structurally indistinguishable from their natural counterparts and showed excellent IgE reactivity suitable for use as certified reference materials. A second tier of allergens (rPhl p 5b, rOle e1, rDer p 1, rDer f 1, and rDer f 2) was identified that could provide suitable candidates for certified reference materials with minor improvements to the recombinant proteins. Only rPhl p 1 was considered unsuitable as a reference material. Quantitative ELISAs were identified that accurately measured each allergen, except for rPhl p 1. The CREATE project has provided a major step forward in allergen standardization and provides a model for the development of a comprehensive panel of international reference preparations that will harmonize allergen measurements worldwide.

Advances in upper airway diseases and allergen immunotherapy in 2007

The purpose of this review is to highlight important articles on upper airway diseases and immunotherapy that appeared in 2007. Advances in rhinitis include the realization that allergic rhinitis might be caused by local nasal IgE sensitization to aeroallergens in the absence of systemic evidence of IgE sensitization. After inhalation, allergens might reach systemic circulation. Epidemiologic studies continue to show that allergic rhinitis impairs school performance and is a risk factor for future asthma. New pathways are being identified in chronic sinusitis, as well as in different types of allergic ocular diseases. New treatments for patients with allergic rhinitis include use of beta-1,3-glucan, a mushroom product that can reduce allergic symptoms by inducing T(H)1 response, and olopatadine nasal spray. Studies on immunotherapy in 2007 suggest that sublingual immunotherapy induces similar immunologic alterations as those induced by subcutaneous immunotherapy, although to a lesser degree. Among allergists in the United States, there is a sizable variation in clinical practice, particularly related to concomitant administration of immunotherapy and beta-blockers, to administration of angiotensin-converting enzyme inhibitors, and to patients with HIV or autoimmune diseases. The combination of omalizumab with allergen subcutaneous immunotherapy can enhance clinical efficacy. Recombinant technology can modify allergen structure to prevent binding to IgE (allergenicity) while enhancing immunogenicity (stimulation of T cells), which might improve the safety and efficacy of immunotherapy.

Sublingual-oral administration of standardized allergenic extracts: phase 1 safety and dosing results

BACKGROUND

European studies provide a preponderance of evidence for sublingual allergen immunotherapy (SLIT) safety and efficacy, but they use allergen products that differ from those expected to be approved in the United States.

OBJECTIVE

To determine the safety and tolerability of 4 US-licensed standardized SLIT allergenic extracts.

METHODS

Adults 18 to 50 years old with allergic rhinitis with or without asthma due to timothy grass pollen, short ragweed pollen, house dust mite, or cat hair allergy completed a single-session dose escalation followed by an 8-week, open-label daily course of SLIT. Participants documented the presence and severity of adverse effects and adherence using a daily electronic diary.

RESULTS

Ninety-one participants initiated treatment, and 77 completed the phase 1 testing. Maximum tolerable doses ranged from 50 to 2,090 BAU for cat hair and dust mite extract, 31 to 91 Amb a 1 Units for short ragweed pollen extract, and 50 to 21,090 BAU for timothy grass pollen extract. During the 8-week treatment course, 98.9% of participants reported at least 1 mild, 70.4% at least 1 moderate, and 13.6% at least 1 severe adverse effect. Most adverse effects (94.6%) were rated as mild, 5.2% as moderate, and 0.1% as severe; nasal and oral-mucosal adverse effects were most commonly reported. No life-threatening adverse reactions occurred in more than 4,500 administered doses.

CONCLUSIONS

Daily sublingual-oral dosing of standardized allergenic extracts at maximum tolerable doses was generally well tolerated. These results are a first step toward establishing the safety of US-licensed SLIT extracts when appropriately self-administered and monitored.