Faculty Bibliography

In the past two decades, food allergy has emerged as an important public health issue in countries with a western life-style. Current management of food allergy relies on dietary avoidance and there is no therapy proven to restore permanent oral tolerance to food. This review focuses on novel approaches to allergen-specific therapy for IgE-mediated food allergy. Oral immunotherapy alone or in combination with anti-IgE antibody is likely to advance into clinical practice in the more immediate future. However, these approaches have to be further validated in large clinical trials before entering clinical practice. Diets containing extensively heated (baked) milk and egg for the majority of milk- and egg-allergic patients represent a safer alternative approach to food oral immunotherapy and are already changing the paradigm of strict dietary avoidance for majority of milk and egg-allergic children.

PURPOSE OF REVIEW/OBJECTIVE:To review current evidence on food oral immunotherapy (OIT). RECENT FINDINGS/RESULTS:Desensitized state, defined as the ingestion of a substantial amount of food in the home diet that protects from severe reactions to accidental exposures, can be achieved by approximately 50-75% of the children treated with OIT. The rate of permanent tolerance is unknown; the longer duration of OIT may result in permanent tolerance. Side effects are common both during the initial dose escalation and during home dosing. Most reactions are mild (oral pruritus, abdominal discomfort, and rashes) and decrease in frequency with the longer duration of OIT. Severe reactions treated with epinephrine have been reported during home dosing. Factors associated with increased risk of reactions to previously tolerated doses during home dosing include exercise, viral infection, dosing on empty stomach, menses, and asthma exacerbation. SUMMARY/CONCLUSIONS:These preliminary data on OIT are encouraging. Additional studies must answer multiple questions including optimal dose, ideal duration of oral/sublingual immunotherapy, degree of protection, efficacy for different ages, severity and type of food allergy responsive to treatment and need for patient protection during home administration. Until these questions are answered in rigorous multicenter randomized and placebo-controlled trials, OIT remains an experimental approach with not sufficiently well established risk-to-benefit ratio.

BACKGROUND:An inactivated influenza vaccine produced in canine kidney cells (MDCK 33016-PF) contains no egg proteins and may be used to immunize egg-allergic patients. Although no major dog allergens were identified in MDCK 33016-PF cells, minor dog allergens might be present and cause reactions in dog-allergic individuals. OBJECTIVE:To evaluate the allergenicity of the inactivated influenza vaccine produced in cell culture in a mediator release assay. METHODS:Rat basophil leukemia (RBL) cells transfected with human IgE receptor-1 were sensitized with sera from dog-allergic adults with positive skin prick test reactions to dog extract and detectable dog dander IgE and were stimulated with serial dilutions of vaccine and dog dander extract. N-hexosaminidase release (NHR) was used as a marker of RBL cell degranulation. Western blots were performed, and UniCAP was used to measure dog-specific IgE antibody levels. RESULTS:The median (interquartile range) level of dog dander IgE was 8.31 kU(A)/L (1.895-14.5 kU(A)/L) and of dog epithelium IgE was 3.19 kU(A)/L (0.835-6.27 kU(A)L). Median (range) maximum NHR (at the first 10-fold dilution) was 0% (0%-1.4%) to vaccine and 10.2% (0%-35.9%) to dog dander (P < .001). In an egg-allergic control subject, the maximum NHR to a vaccine cultured in chick embryo and containing egg protein was 10.2%. IgE antibodies in pooled sera did not bind to vaccine on immunoblots but produced strong binding to dog dander and epithelium extracts. Serum from an egg-allergic control subject strongly bound embryonated egg-derived vaccine. CONCLUSION/CONCLUSIONS:An influenza vaccine produced in continuous canine kidney cells did not trigger degranulation in RBL cells passively sensitized with human anti-dog IgE.

Egg allergy is one of the most frequent food allergies in children below the age of three. Common symptoms of egg allergy involve frequently the skin as well as the gut and in more severe cases result in anaphylaxis. Non-IgE-mediated symptoms such as in eosinophilic diseases of the gut or egg-induced enterocolitis might also be observed. Sensitization to egg white proteins can be found in young children in absence of clinical symptoms. The diagnosis of egg allergy is based on the history, IgE tests as well as standardized food challenges. Ovomucoid is the major allergen of egg, and recent advances in technology have improved the diagnosis and follow-up of patients with egg allergy by using single allergens or allergens with modified allergenic properties. Today, the management of egg allergy is strict avoidance. However, oral tolerance induction protocols, in particular with egg proteins with reduced allergenic properties, are promising tools for inducing an increased level of tolerance in specific patients.

BACKGROUND:Results from large-scale epitope mapping with a peptide microarray have been shown to correlate with clinical features of milk allergy. OBJECTIVES/OBJECTIVE:We sought to assess IgE and IgG4 epitope diversity and IgE affinity in different clinical phenotypes of milk allergy and identify informative epitopes that might be predictive of clinical outcomes of milk allergy. METHODS:Forty-one subjects were recruited from a larger study on the effects of ingesting heat-denatured milk proteins in subjects with milk allergy. Using food challenges, subjects were characterized as being clinically reactive to all forms of milk (n = 17), being tolerant to heated milk (HM) products (n = 16), or having outgrown their milk allergy (n = 8). Eleven healthy volunteers without milk allergy served as control subjects. A peptide microarray was performed by using the previously published protocol. RESULTS:Subjects with milk allergy had increased epitope diversity compared with those who outgrew their allergy. HM-tolerant subjects had IgE-binding patterns similar to those who had outgrown their allergy, but IgG4-binding patterns that were more similar to those of the allergic group. Binding to higher numbers of IgE peptides was associated with more severe allergic reactions during challenge. There was no association between IgG4 peptides and clinical features of milk allergy. Using a competitive peptide microarray assay, allergic patients demonstrated a combination of high- and low-affinity IgE binding, whereas HM-tolerant subjects and those who had outgrown their milk allergy had primarily low-affinity binding. CONCLUSIONS:Greater IgE epitope diversity and higher affinity, as determined by using the peptide microarray, were associated with clinical phenotypes and severity of milk allergy.

BACKGROUND:Data about epinephrine use and biphasic reactions in childhood food-induced anaphylaxis during oral food challenges are scarce. OBJECTIVE:To determine the prevalence and risk factors of reactions requiring epinephrine and the rate of biphasic reactions during oral food challenges (OFCs) in children. METHODS:Reaction details of positive OFCs in children between 1999 and 2007 were collected by using a computerized database. Selection of patients for OFCs was generally predicated on < or =50% likelihood of a positive challenge and a low likelihood of a severe reaction on the basis of the clinical history, specific IgE levels, and skin prick tests. RESULTS:A total of 436 of 1273 OFCs resulted in a reaction (34%). Epinephrine was administered in 50 challenges (11% of positive challenges, 3.9% overall) for egg (n = 15, 16% of positive OFCs to egg), milk (n = 14, 12%), peanut (n = 10, 26%), tree nuts (n = 4, 33%), soy (n = 3, 7%), wheat (n = 3, 9%), and fish (n = 1, 9%). Reactions requiring epinephrine occurred in older children (median, 7.9 vs 5.8 years; P < .001) and were more often caused by peanuts (P = .006) compared with reactions not treated with epinephrine. There was no difference in the sex, prevalence of asthma, history of anaphylaxis, specific IgE level, skin prick tests, or amount of food administered. Two doses of epinephrine were required in 3 of 50 patients (6%) reacting to wheat, cow's milk, and pistachio. There was 1 (2%) biphasic reaction. No reaction resulted in life-threatening respiratory or cardiovascular compromise. CONCLUSION/CONCLUSIONS:Older age and reactions to peanuts were risk factors for anaphylaxis during oral food challenges. Reactions requiring multiple doses of epinephrine and biphasic reactions were infrequent.