Egg-white-specific IgA and IgA2 antibodies in egg-allergic children: is there a role in tolerance induction?

BACKGROUND

Decreased serum food-specific IgA antibodies have been associated with allergic disease in cross-sectional, case-control studies. The purpose of this study was to prospectively compare egg-white-(EW)-specific IgA and IgA2 levels between egg-allergic children and children tolerating egg.

METHODS

Seventeen egg-allergic children were followed prospectively. Total IgA, EW-specific IgA, and EW-specific IgA2 levels were measured in their sera with a sensitive ELISA. As negative controls were used children with no previous history of egg allergy. Egg-allergic children with or without concomitant milk allergy were evaluated as additional controls with measurement of casein-specific IgA.

RESULTS

After 2.5 ± 0.9 yrs, nine out of the 17 allergic children became tolerant and eight remained allergic to baked egg. Baseline EW-specific IgA2 levels were significantly lower in the egg-allergic subjects (median 23.9 ng/ml) compared with the negative control subjects (99.4 ng/ml) and increased significantly by 28% over the study time period in eight out of the nine allergic children that became tolerant to baked egg. There was no significant change over time in EW-specific IgA in any of the study groups. Non-milk-allergic subjects with concomitant egg allergy had almost threefold higher casein-specific IgA levels than the milk- and egg-allergic subjects (p = 0.025).

CONCLUSIONS

These results suggest a potential role for allergen-specific IgA2 antibodies in the induction of food tolerance. Furthermore, they support the hypothesis that immature or impaired production of allergen-specific IgA2 may be associated with the pathophysiology of food allergy, a defect that seems to be selective for the culprit allergen.

The natural history of egg allergy in an observational cohort

BACKGROUND

There are few studies on the natural history of egg allergy, and most are single-site and nonlongitudinal and have not identified early predictors of outcomes.

OBJECTIVE

We sought to describe the natural course of egg allergy and to identify early prognostic markers.

METHODS

Children age 3 to 15 months were enrolled in a multicenter observational study with either (1) a convincing history of an immediate allergic reaction to egg, milk, or both with a positive skin prick test (SPT) response to the trigger food and/or (2) moderate-to-severe atopic dermatitis and a positive SPT response to egg or milk. Children enrolled with a clinical history of egg allergy were followed longitudinally, and resolution was established based on successful ingestion.

RESULTS

The cohort with egg allergy consists of 213 children followed to a median age of 74 months. Egg allergy resolved in 105 (49.3%) children at a median age of 72 months. Factors that were most predictive of resolution included the following: initial reaction characteristics (isolated urticaria/angioedema vs other presentations), baseline egg-specific IgE level, egg SPT wheal size, atopic dermatitis severity, IgG4 level, and IL-4 response (all P < .05). Numerous additional baseline clinical and demographic factors and laboratory assessments were not associated with resolution. Multivariate analysis identified baseline egg-specific IgE levels and initial reaction characteristics as strongly associated with resolution; a calculator to estimate resolution probabilities using these variables was established.

CONCLUSIONS

In this cohort of infants with egg allergy, approximately one half had resolved over 74 months of follow-up. Baseline egg-specific IgE levels and initial reaction characteristics were important predictors of the likelihood of resolution.

Food allergy: Epidemiology, pathogenesis, diagnosis, and treatment

This review focuses on advances and updates in the epidemiology, pathogenesis, diagnosis, and treatment of food allergy over the past 3 years since our last comprehensive review. On the basis of numerous studies, food allergy likely affects nearly 5% of adults and 8% of children, with growing evidence of an increase in prevalence. Potentially rectifiable risk factors include vitamin D insufficiency, unhealthful dietary fat, obesity, increased hygiene, and the timing of exposure to foods, but genetics and other lifestyle issues play a role as well. Interesting clinical insights into pathogenesis include discoveries regarding gene-environment interactions and an increasing understanding of the role of nonoral sensitizing exposures causing food allergy, such as delayed allergic reactions to carbohydrate moieties in mammalian meats caused by sensitization from homologous substances transferred during tick bites. Component-resolved diagnosis is being rapidly incorporated into clinical use, and sophisticated diagnostic tests that indicate severity and prognosis are on the horizon. Current management relies heavily on avoidance and emergency preparedness, and recent studies, guidelines, and resources provide insight into improving the safety and well-being of patients and their families. Incorporation of extensively heated (heat-denatured) forms of milk and egg into the diets of children who tolerate these foods, rather than strict avoidance, represents a significant shift in clinical approach. Recommendations about the prevention of food allergy and atopic disease through diet have changed radically, with rescinding of many recommendations about extensive and prolonged allergen avoidance. Numerous therapies have reached clinical trials, with some showing promise to dramatically alter treatment. Ongoing studies will elucidate improved prevention, diagnosis, and treatment.

Advances in allergic skin disease, anaphylaxis, and hypersensitivity reactions to foods, drugs, and insects in 2013

This review highlights some of the research advances in anaphylaxis; hypersensitivity reactions to foods, drugs, and insects; and allergic skin diseases that were reported in the Journal in 2013. Studies on food allergy suggest that (1) 7.6% of the US population is affected, (2) a "healthy" early diet might prevent food allergy, (3) the skin might be an important route of sensitization, (4) allergen component testing might aid diagnosis, (5) the prognosis of milk allergy might be predictable through early testing, (6) oral or sublingual immunotherapy show promise but also have caveats, and (7) preclinical studies show promising alternative modes of immunotherapy and desensitization. Studies on eosinophilic esophagitis show a relationship to connective tissue disorders and that dietary management is an effective treatment for adults. Markers of anaphylaxis severity have been determined and might inform potential diagnostics and therapeutic targets. Insights on serum tests for drug and insect sting allergy might result in improved diagnostics. Genetic and immune-mediated defects in skin epithelial differentiation contribute to the severity of atopic dermatitis. Novel management approaches to treatment of chronic urticaria, including use of omalizumab, are being identified.

Child and parental reports of bullying in a consecutive sample of children with food allergy

OBJECTIVE

The social vulnerability that is associated with food allergy (FA) might predispose children with FA to bullying and harassment. This study sought to quantify the extent, methods, and correlates of bullying in a cohort of food-allergic children.

METHODS

Patient and parent (83.6% mothers) pairs were consecutively recruited during allergy clinic visits to independently answer questionnaires. Bullying due to FA or for any cause, quality of life (QoL), and distress in both the child and parent were evaluated via questionnaires.

RESULTS

Of 251 families who completed the surveys, 45.4% of the children and 36.3% of their parents indicated that the child had been bullied or harassed for any reason, and 31.5% of the children and 24.7% of the parents reported bullying specifically due to FA, frequently including threats with foods, primarily by classmates. Bullying was significantly associated with decreased QoL and increased distress in parents and children, independent of the reported severity of the allergy. A greater frequency of bullying was related to poorer QoL. Parents knew about the child-reported bullying in only 52.1% of the cases. Parental knowledge of bullying was associated with better QoL and less distress in the bullied children.

CONCLUSIONS

Bullying is common in food-allergic children. It is associated with lower QoL and distress in children and their parents. Half of the bullying cases remain unknown to parents. When parents are aware of the bullying, the child's QoL is better. It is important to proactively identify and address cases in this population.

Sublingual immunotherapy for peanut allergy: a randomized, double-blind, placebo-controlled multicenter trial

BACKGROUND

There are presently no available therapeutic options for patients with peanut allergy.

OBJECTIVE

We sought to investigate the safety, efficacy, and immunologic effects of peanut sublingual immunotherapy (SLIT).

METHODS

After a baseline oral food challenge (OFC) of up to 2 g of peanut powder (approximately 50% protein; median successfully consumed dose [SCD], 46 mg), 40 subjects, aged 12 to 37 years (median, 15 years), were randomized 1:1 across 5 sites to daily peanut or placebo SLIT. A 5-g OFC was performed after 44 weeks, followed by unblinding; placebo-treated subjects then crossed over to higher dose peanut SLIT, followed by a subsequent crossover Week 44 5-g OFC. Week 44 OFCs from both groups were compared with baseline OFCs; subjects successfully consuming 5 g or at least 10-fold more peanut powder than the baseline OFC threshold were considered responders.

RESULTS

After 44 weeks of SLIT, 14 (70%) of 20 subjects receiving peanut SLIT were responders compared with 3 (15%) of 20 subjects receiving placebo (P < .001). In peanut SLIT responders, median SCD increased from 3.5 to 496 mg. After 68 weeks of SLIT, median SCD significantly increased to 996 mg (compared with Week 44, P = .05). The median SCD at the Week 44 Crossover OFC was significantly higher than baseline (603 vs 71 mg, P = .02). Seven (44%) of 16 crossover subjects were responders; median SCD increased from 21 to 496 mg among responders. Of 10,855 peanut doses through the Week 44 OFCs, 63.1% were symptom free; excluding oral-pharyngeal symptoms, 95.2% were symptom free.

CONCLUSIONS

Peanut SLIT safely induced a modest level of desensitization in a majority of subjects compared with placebo. Longer duration of therapy showed statistically significant increases in the SCD.

The natural history of milk allergy in an observational cohort

OBJECTIVE

There are few studies on the natural history of milk allergy. Most are single-site and not longitudinal, and these have not identified a means for early prediction of outcomes.

METHODS

Children aged 3 to 15 months were enrolled in an observational study with either (1) a convincing history of egg allergy, milk allergy, or both with a positive skin prick test (SPT) response to the trigger food and/or (2) moderate-to-severe atopic dermatitis (AD) and a positive SPT response to milk or egg. Children enrolled with a clinical history of milk allergy were followed longitudinally, and resolution was established by means of successful ingestion.

RESULTS

The cohort consists of 293 children, of whom 244 were given a diagnosis of milk allergy at baseline. Milk allergy has resolved in 154 (52.6%) subjects at a median age of 63 months and a median age at last follow-up of 66 months. Baseline characteristics that were most predictive of resolution included milk-specific IgE level, milk SPT wheal size, and AD severity (all P < .001). Baseline milk-specific IgG4 level and milk IgE/IgG4 ratio were not predictive of resolution and neither was expression of cytokine-inducible SH2-containing protein, forkhead box protein 3, GATA3, IL-10, IL-4, IFN-γ, or T-bet by using real-time PCR in CD25-selected, casein-stimulated mononuclear cells. A calculator to estimate resolution probabilities using baseline milk IgE level, SPT response, and AD severity was devised for use in the clinical setting.

CONCLUSIONS

In this cohort of infants with milk allergy, approximately one half had resolved over 66 months of follow-up. Baseline milk-specific IgE level, SPT wheal size, and AD severity were all important predictors of the likelihood of resolution.

Advances in diagnosing peanut allergy

Peanut allergy is often severe, potentially fatal, usually persistent, and appears to have increased in prevalence. An accurate diagnosis is essential because there is a significant burden on quality of life. The tools available for diagnosis include the medical history, skin prick test (SPT), determination of serum peanut-specific IgE antibodies (PN-IgE), and medically supervised oral food challenges. Numerous studies, almost exclusively in children, have correlated clinical outcomes against SPTs and PN-IgE with informative results. The diagnostic utility of SPT and PN-IgE is maximized by considering the degree of positive result and consideration of the medical history (a priori estimation of risk). Emerging tests that evaluate IgE binding to specific proteins in peanut (component testing) add important additional diagnostic information in specific settings. Studies are increasingly focused on how the results of tests considered in combination (or performed serially) may increase diagnostic accuracy. Here, we review the utility of currently available tests and provide suggestions on how to best use them to accurately predict peanut allergy. Still, the physician-supervised oral food challenge remains the most definitive test available.

Advances in allergic skin disease, anaphylaxis, and hypersensitivity reactions to foods, drugs, and insects in 2012

This review highlights some of the research advances in anaphylaxis; hypersensitivity reactions to foods, drugs, and insects; and allergic skin diseases that were reported in the Journal in 2012. Studies support an increase in peanut allergy prevalence in children and exposure to the antibacterial agent triclosan and having filaggrin (FLG) loss-of-function mutations as risk factors for food sensitization. The role of specific foods in causing eosinophilic esophagitis is elucidated by several studies, and microRNA analysis is identified as a possible noninvasive disease biomarker. Studies on food allergy diagnosis emphasize the utility of component testing and the possibility of improved diagnosis through stepped approaches, epitope-binding analysis, and bioinformatics. Treatment studies of food allergy show promise for oral immunotherapy, but tolerance induction remains elusive, and additional therapies are under study. Studies on anaphylaxis suggest an important role for platelet-activating factor and its relationship to the need for prompt treatment with epinephrine. Insights on the pathophysiology and diagnosis of non-IgE-mediated drug allergy are offered, with novel data regarding the interaction of drugs with HLA molecules. Numerous studies support influenza vaccination of persons with egg allergy using modest precautions. Evidence continues to mount that there is cross-talk between skin barrier defects and immune responses in patients with atopic dermatitis. Augmentation of the skin barrier with reduction in skin inflammatory responses will likely lead to the most effective intervention in patients with this common skin disease.

An assessment of the mental health care needs and utilization by families of children with a food allergy

The present study aimed to examine whether caretakers of children with a food allergy experience distress and to determine their family’s mental health-care needs and utilization. An anonymous survey was given to a sample of 454 caretakers during conferences hosted by the Food Allergy & Anaphylaxis Network. Overall, 32 percent of caretakers reported above threshold levels of distress while 70 percent stated that mental health support would have been helpful, but only 23 percent sought it. Even when mental health support was desired and available, few received it. Routine discussion of mental health needs with families receiving medical care may help address barriers to utilization.

Oral immunotherapy for treatment of egg allergy in children

BACKGROUND

For egg allergy, dietary avoidance is the only currently approved treatment. We evaluated oral immunotherapy using egg-white powder for the treatment of children with egg allergy.

METHODS

In this double-blind, randomized, placebo-controlled study, 55 children, 5 to 11 years of age, with egg allergy received oral immunotherapy (40 children) or placebo (15). Initial dose-escalation, build-up, and maintenance phases were followed by an oral food challenge with egg-white powder at 10 months and at 22 months. Children who successfully passed the challenge at 22 months discontinued oral immunotherapy and avoided all egg consumption for 4 to 6 weeks. At 24 months, these children underwent an oral food challenge with egg-white powder and a cooked egg to test for sustained unresponsiveness. Children who passed this challenge at 24 months were placed on a diet with ad libitum egg consumption and were evaluated for continuation of sustained unresponsiveness at 30 months and 36 months.

RESULTS

After 10 months of therapy, none of the children who received placebo and 55% of those who received oral immunotherapy passed the oral food challenge and were considered to be desensitized; after 22 months, 75% of children in the oral-immunotherapy group were desensitized. In the oral-immunotherapy group, 28% (11 of 40 children) passed the oral food challenge at 24 months and were considered to have sustained unresponsiveness. At 30 months and 36 months, all children who had passed the oral food challenge at 24 months were consuming egg. Of the immune markers measured, small wheal diameters on skin-prick testing and increases in egg-specific IgG4 antibody levels were associated with passing the oral food challenge at 24 months.

CONCLUSIONS

These results show that oral immunotherapy can desensitize a high proportion of children with egg allergy and induce sustained unresponsiveness in a clinically significant subset. (Funded by the National Institutes of Health; ClinicalTrials.gov number, NCT00461097.).

Advances in allergic skin disease, anaphylaxis, and hypersensitivity reactions to foods, drugs, and insects in 2011

This review highlights some of the research advances in anaphylaxis; hypersensitivity reactions to foods, drugs, and insects; and allergic skin diseases that were reported in the Journal in 2011. Food allergy appears to be increasing in prevalence and carries a strong economic burden. Risk factors can include dietary ones, such as deficiency of vitamin D and timing of complementary foods, and genetic factors, such as filaggrin loss-of-function mutations. Novel mechanisms underlying food allergy include the role of invariant natural killer T cells and influences of dietary components, such as isoflavones. Among numerous preclinical and clinical treatment studies, promising observations include the efficacy of sublingual and oral immunotherapy, a Chinese herbal remedy showing promising in vitro results, the potential immunotherapeutic effects of having children ingest foods with baked-in milk if they tolerate it, and the use of anti-IgE with or without concomitant immunotherapy. Studies of allergic skin diseases, anaphylaxis, and hypersensitivity to drugs and insect venom are elucidating cellular mechanisms, improved diagnostics, and potential targets for future treatment. The role of skin barrier abnormalities, as well as the modulatory effects of the innate and adaptive immune responses, are major areas of investigation.

Allergic reactions to foods in preschool-aged children in a prospective observational food allergy study

OBJECTIVE

To examine circumstances of allergic reactions to foods in a cohort of preschool-aged children.

METHODS

We conducted a prospective, 5-site observational study of 512 infants aged 3 to 15 months with documented or likely allergy to milk or egg, and collected data prospectively examining allergic reactions.

RESULTS

Over a median follow-up of 36 months (range: 0-48.4), the annualized reaction rate was 0.81 per year (367/512 subjects reporting 1171 reactions [95% confidence interval: 0.76-0.85]). Overall, 269/512 (52.5%) reported >1 reaction. The majority of reactions (71.2%) were triggered by milk (495 [42.3%]), egg (246 [21.0%]), and peanut (93 [7.9%]), with accidental exposures attributed to unintentional ingestion, label-reading errors, and cross-contact. Foods were provided by persons other than parents in 50.6% of reactions. Of 834 reactions to milk, egg, or peanut, 93 (11.2%) were attributed to purposeful exposures to these avoided foods. A higher number of food allergies (P < .0001) and higher food-specific immunoglobulin E (P < .0001) were associated with reactions. Of the 11.4% of reactions (n = 134) that were severe, 29.9% were treated with epinephrine. Factors resulting in undertreatment included lack of recognition of severity, epinephrine being unavailable, and fears about epinephrine administration.

CONCLUSIONS

There was a high frequency of reactions caused by accidental and nonaccidental exposures. Undertreatment of severe reactions with epinephrine was a substantial problem. Areas for improved education include the need for constant vigilance, accurate label reading, avoidance of nonaccidental exposure, prevention of cross-contamination, appropriate epinephrine administration, and education of all caretakers.

Timing the transfer of responsibilities for anaphylaxis recognition and use of an epinephrine auto-injector from adults to children and teenagers: pediatric allergists' perspective

BACKGROUND

The optimal time for transferring responsibilities for anaphylaxis recognition and epinephrine auto-injector use from adults to children and teenagers has not yet been defined.

OBJECTIVE

To determine whether pediatric allergists have age-specific goals for beginning to transfer responsibilities for anaphylaxis recognition and epinephrine auto-injector use from parents and caregivers to children and teenagers at risk of anaphylaxis in the community.

METHODS

Members of the American Academy of Pediatrics Section on Allergy and Immunology (AAP-SOAI) were surveyed about when they typically begin to transfer these responsibilities from adults to children and teenagers.

RESULTS

Eighty-eight allergists responded to the survey, 97.7% of whom provided service to children and teenagers with food allergies. Few allergists expected to begin transferring responsibilities for anaphylaxis recognition and epinephrine auto-injector use to children younger than 9 to 11 years. By the time their patients reached age 12 to 14 years, however, most allergists expected them to be able to describe some anaphylaxis symptoms (95.4%), demonstrate how to use an epinephrine auto-injector trainer (93.1%), begin carrying self-injectable epinephrine (88.2%), recognize the need for epinephrine (88.1%), learn to self-inject epinephrine (84.5%), and be able to self-inject epinephrine (78.6%) (cumulative data). The allergists rated the following as "very important" readiness factors for beginning to transfer responsibilities: medical history, developmental level, and ability to demonstrate auto-injector technique.

CONCLUSION

Most pediatric allergists expected that by age 12 to 14 years, their patients should begin to share responsibilities with adults for anaphylaxis recognition and epinephrine auto-injector use; however, they individualized the timing based on assessment of patient readiness factors.

Development and validation of educational materials for food allergy

OBJECTIVE

To develop and validate a food allergy educational program.

STUDY DESIGN

Materials developed through focus groups and parental and expert review were submitted to 60 parents of newly referred children with a prior food allergy diagnosis and an epinephrine autoinjector. The main outcome was correct demonstration of an autoinjector.

RESULTS

The correct number of autoinjector activation steps increased from 3.4 to 5.95 (of 6) after training (P < .001) and was 5.47 at 1 year (P < .05). The mean score for comfort with using the autoinjector (7-point Likert scale) before the curriculum was 4.63 (somewhat comfortable) and increased to 6.23 after the intervention (P < .05) and remained elevated at 1 year (6.03). Knowledge tests (maximum 15) increased from a mean score of 9.2 to 12.4 (P < .001) at the initial visit and remained at 12.7 at 1 year. The annualized rate of allergic reactions fell from 1.77 (historical) the year prior, to 0.42 (P < .001) after the program. On a 7-point Likert scale, all satisfaction categories remained above a favorable mean score of 6: straight-forward, organized, interesting, relevant, and recommend to others.

CONCLUSIONS

This food allergy educational curriculum for parents, now available online at no cost, showed high levels of satisfaction and efficacy.

Food allergy

Food allergy appears to be increasing in prevalence and is estimated to affect >2% and possibly up to 10% of the population. Food allergies are defined by an immune response triggered by food proteins. Emerging data suggest that carbohydrate moieties on food proteins, specifically mammalian meats, may also elicit allergic responses. Food is the most common trigger of anaphylaxis in the community, which can be fatal. The underlying mechanisms of food allergy usually involve food-specific immunoglobulin E antibodies, but cell-mediated disorders account for a variety of chronic or subacute skin and gastrointestinal reactions. Eosinophilic esophagitis is an emerging food-related chronic disorder. The diagnosis of food allergy is complicated by the observation that detection of food-specific immunoglobulin E (sensitization) does not necessarily indicate clinical allergy. Diagnosis requires a careful medical history, laboratory studies, and, in many cases, oral food challenges to confirm a diagnosis. Novel diagnostic methods, many of which rely upon evaluating immune responses to specific food proteins or epitopes, may improve diagnosis and prognosis in the future. Current management relies upon allergen avoidance and preparation to promptly treat severe reactions with epinephrine. Studies suggest that some children with milk or egg allergy might tolerate extensively heated forms, for example milk or egg baked into muffins, without symptoms and possibly with some immunotherapeutic benefits. Novel therapeutic strategies are under study, including oral and sublingual immunotherapy, Chinese herbal medicine, anti-immunoglobulin E antibodies, and modified vaccines.

Allergy testing in childhood: using allergen-specific IgE tests

A variety of triggers can induce common pediatric allergic diseases which include asthma, allergic rhinitis, atopic dermatitis, food allergy, and anaphylaxis. Allergy testing serves to confirm an allergic trigger suspected on the basis of history. Tests for allergen-specific immunoglobulin E (IgE) are performed by in vitro assays or skin tests. The tests are excellent for identifying a sensitized state in which allergen-specific IgE is present, and may identify triggers to be eliminated and help guide immunotherapy treatment. However, a positive test result does not always equate with clinical allergy. Newer enzymatic assays based on anti-IgE antibodies have supplanted the radioallergosorbent test (RAST). This clinical report focuses on allergen-specific IgE testing, emphasizing that the medical history and knowledge of disease characteristics are crucial for rational test selection and interpretation.