Oral rush desensitization to egg: efficacy and safety

Developments in the field of allergy in 2011 through the eyes of Clinical and Experimental Allergy

As in previous years, we felt it would be of value to our readership to summarize the new information provided by the authors who have published in Clinical and Experimental Allergy in 2011 and set this in the context of recent advances in our understanding of the pathogenesis and management of allergic disease in all its many manifestations. In 2011, about 210 articles were published in Clinical and Experimental Allergy including editorials, reviews, opinion articles, guidelines, letters, book reviews and of course at the heart of the journal, papers containing original data. As before, this review is divided into sections based on the way the journal is structured, although this year we have grouped together all the papers dealing with mechanisms of allergic disease, whether they involve patients (clinical mechanisms), pure in vitro studies (basic mechanisms) or animal models (experimental models), as we felt this was a more coherent way to deal with the subject. In the field of asthma and rhinitis, the relationship between airway inflammation and airway dysfunction was of perennial interest to investigators, as were phenotypes and biomarkers. Aspirin hypersensitivity appeared in studies in several papers and there was new interest in asthma in the elderly. The mechanisms involved in allergic disease describe advances in our understanding of T cell responses, the relationship between inflammation and disease, mast cell and basophil activation, steroid resistance and novel therapies. In the section dealing with epidemiology, studies seeking to identify risk factors for allergic disease including vitamin D are prominent, as once again are studies investigating gene-environment interactions. The clinical allergy section focuses on drug allergy, food allergy and immunotherapy. The area of oral immunotherapy for food allergy is well covered and we were grateful to Stephen Durham for guest editing an outstanding special issue on immunotherapy in the centenary year of Leonard Noon's pioneering work. Lastly, in the field of allergens, the interest in component-resolved diagnosis continues to grow and there are also articles describing important novel cultivars and the effect of food processing on the allergenic properties of foods. Another terrific year, full of important and high-quality work,which the journal has been proud to bring to the allergy community.

Specific oral tolerance induction in paediatric patients with persistent egg allergy

INTRODUCTION

Desensitisation or specific oral tolerance induction (SOTI) to food is a new topical-therapeutic approach of food allergy for those children who have not achieved tolerance spontaneously. The objective of this study is to induce clinical tolerance in children with persistent allergy using an oral desensitisation protocol with powdered pasteurised egg.

METHODS

Seventy-two patients with egg allergy confirmed by open oral challenge test were randomly assigned to SOTI or elimination diet as a control group. Forty children (5-15 years) underwent a SOTI beginning with 1mg and increasing the dosage weekly until a dose of 10g, equivalent to an egg. The control group included 32 patients (4-15 years).

RESULTS

The procedure's average duration was 10 weeks (range 4-28 weeks). Three patients were withdrawn from the protocol for persistent gastrointestinal symptoms. During SOTI, 21 children (52.5%) presented symptoms. In eight the symptoms were mild and required no treatment. In the other 13 (61.90%), the reactions were more severe. Seventeen children finished the treatment over a year ago and 20 in the past 6-12 months. Thirty-seven patients (92.5%) in the active group achieved tolerance to egg, versus 21.8% in the control group. We only found statistically significant differences (p<0.05) for skin prick tests with powdered egg at various dilutions and IgG levels with egg white after SOTI. Specific IgE concentration did not change significantly.

CONCLUSIONS

Our SOTI protocol is a safe, effective treatment for food allergy and of reasonable duration, confirming that tolerance can be induced in children who have not achieved it spontaneously.

New directions in immunotherapy

Allergen immunotherapy (AIT) is effective in reducing the clinical symptoms associated with allergic rhinitis, asthma and venom-induced anaphylaxis. Subcutaneous (SCIT) and sublingual immunotherapy (SLIT) with unmodified allergen extracts are the most widely prescribed AIT regimens. The efficacy of these 2 routes appears comparable, but the safety profile with SLIT is more favorable allowing for home administration and requiring less patient time. However, both require that the treatment is taken regularly over several years, e.g., monthly in a supervised medical setting with SCIT and daily at home with SLIT. Despite the difference in treatment settings, poor adherence has been reported with both routes. Emerging evidence suggests that AIT may be effective in other allergic conditions such as atopic dermatitis, venom sting-induced large local reactions, and food allergy. Research with oral immunotherapy (OIT) for food allergies suggest that many patients can be desensitized during treatment, but questions remain about whether this can produce long term tolerance. Further studies are needed to identify appropriate patients and treatment regimens with these conditions. Efforts to develop safer and more effective AIT for inhalant allergies have led to investigations with modified allergens and alternate routes. Intralymphatic (ILIT) has been shown to produce long-lasting clinical benefits after three injections comparable to a 3-year course of SCIT. Epicutaneous (EPIT) has demonstrated promising results for food and inhalant allergies. Vaccine modifications, such as T cell epitopes or the use of viral-like particles as an adjuvant, have been shown to provide sustained clinical benefits after a relatively short course of treatment compared to the currently available AIT treatments, SLIT and SCIT. These newer approaches may increase the utilization and adherence to AIT because the multi-year treatment requirement of currently available AIT is a likely deterrent for initiating and adhering to treatment.

Sublingual vs oral immunotherapy for food allergy: identifying the right approach

The incidence of food allergy in developed countries has increased in recent years, escalating the need to find a suitable form of treatment as an alternative to current management, which includes strict avoidance and ready availability of injectable epinephrine (adrenaline). Allergen immunotherapy is currently being studied for use in the treatment of IgE-mediated food allergy to the most common foods, including peanut, tree nut, milk and egg. Two modalities, oral immunotherapy (OIT) and sublingual immunotherapy (SLIT), have shown great promise. Both OIT and SLIT have been able to desensitize subjects to varying degrees, but the two treatment methods differ in doses that can be achieved, duration of treatment, safety profile and ease of use outside the research setting, among other aspects. More research is needed to conclude which mode of treatment is more effective in inducing long-term tolerance with the least amount of serious adverse reactions. However, OIT and SLIT show great promise, and a widespread treatment for food allergy may be within reach.

Oral food desensitization in children with IgE-mediated hen's egg allergy: a new protocol with raw hen's egg

BACKGROUND

Hen's egg allergy affects young children and can cause severe allergic reactions. Avoidance results in dietary limitations and can affect the quality of life, especially in cases where potentially life-threatening reactions exist. Our objective was to desensitize children with moderate-severe IgE-mediated hen's egg allergy over a 6-month period, by introducing increasing and very gradual daily doses of raw hen's egg in order to enable the children to assume 25ml of this food, or to induce tolerance to the highest possible dose. The protocol foresaw the egg reintroduction in the home setting.

METHODS

In this randomized, controlled open study, 20 hen's egg allergic children (10 in the active group) were admitted. A convincing history or a positive double-blind placebo-controlled food challenge confirmed the diagnosis. Oral desensitization was performed with increasing doses starting from 0.27 mg of hen's egg proteins (1 drop of raw hen's egg diluted 1:100). We adopted an original, mathematically calculated protocol in order to ensure a constant, daily increment of doses.

RESULTS

8/10 children (80%) in the active group achieved the daily intake of 25ml over a 6-month period. One child (10%) could tolerate up to 2ml/day while another child (10%) failed the desensitization. Six months after enrolment only 2 children in the control group (20%) could tolerate hen's egg.

CONCLUSIONS

We successfully desensitized 8/10 children with IgE-mediated hen's egg allergy in a 6-month period. The partial outcome in the child who could tolerate 2ml/day reduced the risk of severe reactions after unnoticed introduction of egg. A regular protocol that ensures a daily constant increase of doses helps to reduce possible adverse events, thus improving safety and effectiveness.

Specific oral tolerance induction with raw hen's egg in children with very severe egg allergy: a randomized controlled trial

BACKGROUND

Treatment of severe egg allergy is avoidance of hen's egg (HE) and carrying self-injectable epinephrine. Specific oral tolerance induction (SOTI) seems a promising alternative treatment. However, some aspects of SOTI are still considered experimental.

METHODS

We evaluated the efficacy and safety of an original 6-month SOTI protocol in children with very severe HE allergy using raw HE emulsion. Twenty children (age range: 5-11 yr) were randomized equally into a SOTI treatment group and a control group. The treatment group started SOTI and underwent a second challenge 6 months later. Control children were kept on an egg-free diet for 6 months and then underwent a second challenge.

RESULTS

After 6 months, 9/10 children of the SOTI group (90%) achieved partial tolerance (at least 10 ml, but <40 ml of raw HE emulsion, in a single dose) and 1 (10%) was able to tolerate only 5 ml (no tolerance). After 6 months, nine control children tested positive to the second challenge at a dose ≤0.9 ml of raw HE emulsion, and one reacted to 1.8 ml (SOTI vs. control group p<0.0001). All children in the SOTI group had side effects, but no child had a grade 5 reaction according to the Sampson grading.

CONCLUSION

Six months of SOTI with raw HE emulsion resulted in partial tolerance, with regular intake, in a significant percentage of children with severe egg allergy.

Peanut oral immunotherapy: is it ready for clinical practice?

The prevalence of peanut allergy in the United States and other Westernized countries has tripled in the past 15 years, now affecting more than 1% of the population. Strict peanut avoidance is the current standard of care. In the past decade, a number of small, largely uncontrolled clinical trials have suggested that oral immunotherapy (OIT) can effectively desensitize most children with peanut allergy. Some in the allergy community now feel that OIT is ready for clinical practice. In this review, the evidence base in the medical literature is examined. Although peanut OIT shows promise, the evidence currently available on its effectiveness, risk benefit, and potential long-term consequences is insufficient to support its use in clinical practice. Appropriately designed, prospective clinical trials are urgently needed to determine whether OIT is a safe, effective form of therapy for food allergy.

Oral immunotherapy in hen's egg-allergic children increases a hypo-proliferative subset of CD4+ T cells that could constitute a marker of tolerance achievement

BACKGROUND

Food allergy affects a significant number of children and its prevalence, and persistence is undergoing an important increase in the last years. Specific oral tolerance induction (SOTI) is a promising therapy for food allergy. However, little is known about the immune mechanisms implicated in the desensitization to allergens. Our purpose was to study which immune parameters are modified during the process of tolerance achievement with the goal of identifying markers of tolerance induction.

METHODS

We performed an extensive immune analysis in 19 allergic children following SOTI with hen's egg before and after the immunotherapy. Changes in lymphocyte subpopulations and serum cytokines were identified in children with desensitization achievement.

RESULTS

Sixteen children achieved complete tolerance to egg, and the immune analysis reveals that desensitization was accompanied in all the cases by a significant decrease in the percentage and absolute counts of effector-memory CD4+ T cells (T(EM) ) and a marked increase in the absolute counts of a subset of CD4(+) CD38(+) CD45RO(-) cells. Additionally, we also observed a marked reduction in the plasma levels of different Th1 and Th2 cytokines after tolerance achievement.

CONCLUSIONS

Acquisition of tolerance in children after oral immunotherapy is accompanied by a decrease in the T(EM) population and the increase in a particular subset of CD4+ T cells with a hypo-proliferative and non-reactive phenotype. This hypo-proliferative subset of cells could constitute a marker of the development of oral tolerance, and the study of this subset could contribute to the better understanding of the immune responses in allergic subjects.

[Indications and evidence base for specific immunotherapy in childhood]

Allergic rhinitis (AR) is a common disease affecting 7-17% of children and adolescents who may suffer from a significantly impaired quality of life. For 100 years subcutaneous immunotherapy (SCIT) has been used to treat AR. If patients are chosen carefully, a clinically relevant reduction of seasonal symptoms and medication use can be achieved by SCIT. Serious adverse events are rarely encountered during adequately performed and monitored SCIT. Sublingual immunotherapy (SLIT) may be used as a less painful therapeutic alternative in children if the administration of SCIT is impossible. Recent controlled trials have shown that SLIT performed over one pollen season also ameliorates seasonal symptoms and reduces the need for concomitant medication. Local reactions are frequently encountered during SLIT whereas systemic and life-threatening adverse events under correctly performed SLIT have not been reported so far.

Ovomucoid (Gal d 1) specific IgE detected by microarray system predict tolerability to boiled hen's egg and an increased risk to progress to multiple environmental allergen sensitisation

BACKGROUND

Egg allergy is a very common finding in early childhood. Detecting hen's egg (HE) allergy outgrowing and reintroduction of food containing egg is a task for the allergist.

OBJECTIVE

We sought to evaluate the suitability of boiled egg food challenge compared with IgE to allergenic molecules from HE white using a microarray system.

METHOD

Sixty-eight children referring to our centre by the family paediatricians for a suspected egg allergy were enrolled. Patients underwent double-blind, placebo-controlled food challenge with boiled and raw eggs. Challenge outcomes were compared with skin tests performed using egg white and yolk commercial extracts, to prick-prick test with boiled and raw egg white and yolk, total IgE, egg white specific IgE detected using ImmunoCAP and IgE to egg allergens available on the immunosolid phase allergen chip (ISAC) 103 microarray.

RESULT

Nineteen subjects (28%) were reactive to both raw and boiled egg, 14 (20.5%) to raw egg only and 35 (51.4%) tolerated both boiled and raw egg. Efficiency analysis was carried out using both raw and boiled egg challenges as gold standard. Forty four of 47 Gal d 1 negative patients tolerated boiled egg (94%). Conversely, 20 of 21 Gal d 1 positive patients reacted to raw egg (95%). None of the other tests was able to discriminate patients' response to HE challenge. Furthermore, Gal d 1 positivity seems to lead to broader environmental allergen IgE sensitization.

CONCLUSION AND CLINICAL RELEVANCE

The Gal d 1 IgE reactivity appears to be a very good predictor of HE clinical allergy. Gal d 1 positive children have a high frequency of HE allergy, whereas Gal d 1 negative children have a high frequency of tolerance to boiled egg. Multiple specific IgE detection by means of ISAC improves the diagnostic approach in HE allergic children, disclosing other food and inhalant allergic sensitizations, anyhow requiring a comprehensive clinical evaluation.