Research Area: Nut Allergy

Pumphrey, R., 2004. Anaphylaxis: can we tell who is at risk of a fatal reaction? Curr Opin Allergy Clin Immunol.  4:285–290.

Purpose of review: Anaphylaxis is frightening and patients commonly fear their next reaction will be fatal. This review looks at the characteristics of fatal reactions to find if a fatal recurrence is predictable. Recent findings: Most publications on fatal anaphylaxis are case reports that do not help predict risks. Most epidemiological studies focus on non-fatal reactions. The UK fatal anaphylaxis register demonstrates that over two-thirds of those dying from sting reactions and over four-fifths dying from drug anaphylaxis had no previous indication of their allergy, whereas those dying from food allergy had usually had previous reactions but these were typically not severe. Recent reports of anaphylaxis epidemiology based on diagnostic coding or attendance for treatment may be biased by differences in health service resource utilization according to the cause and course of the reaction. Summary: Most fatal anaphylactic reactions are unpredictable. The appropriate management after recovery from a severe reaction may be protective against a fatal recurrence. An accurate identification of the cause and effective avoidance is a crucial part of this management, together with effective treatment of asthma for those with food allergy, immunotherapy for sting allergy, the avoidance of drugs that potentiate anaphylaxis, and effective training in self-treatment.

Moneret-Vautrin, D.A., G. Kanny, 2004. Update on threshold doses of food allergens: implications for patients and the food industry. Curr Opin Allergy Clin Immunol. 4:215–219.

The purpose of this review is to bring the reader up to date on the importance of assessing a food’s lowest observed adverse effect level (LOAEL) with two aims. Firstly, to help industry choose tests with a level of sensitivity capable of detecting food allergens hidden in industrial products. Secondly, to specify protective measures for highly allergic individuals in order to prevent recurrent severe anaphylaxis. The review also seeks to highlight the present issues and unsolved questions. Recent findings Thanks to standardized oral-provocation tests (double-blind placebo-controlled food challenges), LOAELs have been identified for many IgE-dependent food allergies. Most studies concern the pediatric population. Data is available for milk, egg, peanut, wheat flour, and sesame. The LOAELs are commonly in the range of 1–2 mg of natural foods, representing a few hundred micrograms of protein. These minimal reactive doses characterize about 1% of people allergic to milk, egg, or peanut. The level at which no observed adverse effect is seen might be a few tens of micrograms of protein for peanut. At the present time, allergy to oil seems to be restricted to unrefined cold-pressed oils. Summary Concerning IgE-dependent food allergies, the threshold dose inducing symptoms is now known to vary a great deal according to the individual. A reactive dose of less than 65 mg characterizes 16 and 18% of patients allergic to egg or peanut. Less than 30 mg of milk proteins characterizes 5% of those allergic to milk. For milk, egg, and peanut, 1% of patients have a very low threshold, about 1 mg. Such data emphasize the necessity of using detection tests with a sensitivity better than 10 parts per million. The modifications of allergenicity undergone by protein ingredients that are now commonly introduced into industrially made products are not yet sufficiently known. A better knowledge of the reactive doses of these proteins is needed.

Hand, S., C. Darke, J. Thompson, C. Stingl, S. Rolf, K.P. Jones, B.H. Davies, 2004. Human leucocyte antigen polymorphisms in nut-allergic patients in South Wales. Clin Exp Allergy. 34:720–724.

Background: Peanuts and tree nuts are among the most common foods provoking severe allergic reactions including fatal anaphylaxis. However, little is known of the underlying genetic and immunological mechanisms involved. Objective: Based on findings in other allergic diseases, we have investigated whether specific human leucocyte antigens (HLA) are associated with nut allergy. Method Eighty-four patients presenting at the allergy clinic with symptoms of nut allergy were typed for the HLA Class I (HLA-A and B) and Class II (HLA-DRB1 and DQB1) loci by PCR using sequence-specific primers. Carriage frequencies were compared with 82 atopic non-nut-allergic subjects and 1798 random blood donors. Results: The frequency of HLA-B*07 (28.57%) and DRB1*11 (15.48%) was increased in the nutallergic patients compared to the atopic controls (12.20% and 3.66%, respectively) but not when compared to the blood donors (28.86% and 10.12%). DRB1*13 and DQB1*06 were both increased in frequency in the nut allergy patients over both the atopic and blood donor controls. However, none of these increased frequencies were significant when corrected for the number of comparisons undertaken. Conclusion: At HLA ‘2-digit resolution’ and with undifferentiated patients with nut allergy, there are no major disturbances in the frequency of HLA-A, B, DRB1 or DQB1 types. However, the difference in frequency of HLA-DRB1*11 between the nut allergy patients and the atopic controls merits further investigation as this may represent an important phenotypic relationship.

Clark, S., S. Allan Bock, T.J. Gaeta, B.E. Brenner, R.K. Cydulka, C.A. Camargo, on behalf of the Multicenter Airway Research Collaboration–8 Investigators, 2004. Multicenter study of emergency department visits for food allergies. J Allergy Clin Immunol. 113:347-352.

Background: Relatively little is known about the characteristics of patients who visit the emergency department (ED) for an acute allergic reaction. Although anaphylaxis guidelines suggest treatment with epinephrine, teaching about self-injectable epinephrine, and referral to an allergist, current ED management remains uncertain. Objective: The objective of this study was to describe the management of food-related acute allergic reactions. Methods: The Multicenter Airway Research Collaboration performed a chart review study in 21 North American EDs. Investigators reviewed a random sample of 678 charts of patients who presented with food allergy (International Classification of Diseases–ninth revision codes 693.1, 995.0, 995.3, and 995.60-995.69). Results: Patients had an average age of 29 years; the cohort was 57% female and 40% white. A variety of foods provoked the allergic reaction, including nuts (21%), crustaceans (19%), fruit (12%), and fish (10%). Although exposure to these foods can be life threatening, only 18% of patients came to the ED by ambulance. In the ED, 72% of patients received antihistamines, 48% received systemic corticosteroids, and 16% received epinephrine; 33% received respiratory treatments such as inhaled albuterol. Among patients with severe reactions (55% of total), 24% received epinephrine. Overall, 97% of patients were discharged to home. At ED discharge, 16% of patients were prescribed self-injectable epinephrine, and 12% were referred to an allergist. Conclusions: Although guidelines suggest specific approaches for the management of acute allergic reactions, ED concordance for food allergy appears low. These findings support a new collaboration between professional organizations in allergy and emergency medicine and the development of educational programs and materials for ED patients and staff.

Sampson, H.A., 2004. Update on Food Allergy. J. Allergy Clin Immunol. 113:805-819.

Tremendous progress has been made in our understanding of food-based allergic disorders over the past 5 years. Recent epidemiologic studies suggest that nearly 4% of Americans are afflicted with food allergies, a prevalence much higher than appreciated in the past. In addition, the prevalence of peanut allergy was found to have doubled in American children less than 5 years of age in the past 5 years. Many food allergens have been characterized at the molecular level, which has contributed to our increased understanding of the immunopathogenesis of many allergic disorders and might soon lead to novel diagnostic and immunotherapeutic approaches. The management of food allergies continues to consist of educating patients on how to avoid relevant allergens, to recognize early symptoms of an allergic reaction in case of an accidental ingestion, and to initiate the appropriate emergency therapy. However, the recent successful clinical trial of anti-IgE therapy in patients with peanut allergy and the number of  immunomodulatory therapies in the pipeline provide real hope that we will soon be able to treat patients with food allergy.