Anaphylaxis and food allergy

Food Allergy Testing

Although the gold standard for diagnosis of immunoglobulin E (IgE)-mediated food allergy is an oral food challenge, clinically relevant biomarkers of IgE sensitization, including serum-specific IgE and skin prick testing, can aid in diagnosis. Clinically useful values have been defined for individual foods. More recently, specific IgE to particular protein components has provided additional diagnostic value. In summary, food allergy diagnostics to evaluate IgE sensitization are clinically useful and continue to evolve to improve evaluation of IgE-mediated food allergies.

IL-9-producing cells in the development of IgE-mediated food allergy

Food allergy is a harmful immune reaction driven by uncontrolled type 2 immune responses. Considerable evidence demonstrates the key roles of mast cells, IgE, and TH2 cytokines in mediating food allergy. However, this evidence provides limited insight into why only some, rather than all, food allergic individuals are prone to develop life-threatening anaphylaxis. Clinical observations suggest that patients sensitized to food through the skin early in life may later develop severe food allergies. Aberrant epidermal thymic stromal lymphopoietin and interleukin (IL) 33 production and genetic predisposition can initiate an allergic immune response mediated by dendritic cells and CD4+TH2 cells in inflamed skin. After allergic sensitization, intestinal IL-25 and food ingestion enhance concerted interactions between type 2 innate lymphoid cells (ILC2s) and CD4+TH2 cells, which perpetuate allergic reactions from the skin to the gut. IL-4 and cross-linking of antigen/IgE/FcεR complexes induce emigrated mast cell progenitors to develop into the multi-functional IL-9-producing mucosal mast cells, which produce prodigious amounts of IL-9 and mast cell mediators to drive intestinal mastocytosis in an autocrine loop. ILC2s and TH9 cells may also serve as alternative cellular sources of IL-9 to augment the amplification of intestinal mastocytosis, which is the key cellular checkpoint in developing systemic anaphylaxis. These findings provide a plausible view of how food allergy develops and progresses in a stepwise manner and that atopic signals, dietary allergen ingestion, and inflammatory cues are fundamental in promoting life-threatening anaphylaxis. This information will aid in improving diagnosis and developing more effective therapies for food allergy-triggered anaphylaxis.

Systemic delivery of alpha-asarone with Kolliphor HS 15 improves its safety and therapeutic effect on asthma

The commercially available alpha-asarone injections (CA-ARE) were frequently found to cause severe anaphylactic reactions by the solubilizer contained in the formulation such as polysorbate 80 and propylene glycol. This study aimed to develop a new ARE injection using Kolliphor HS 15 as solubilizing agent (HS 15-ARE) by the dissolution method to resolve its poor solubility problem and reduce the anaphylaxis of CA-AREs caused by Polysorbate 80. The HS 15-ARE micelle showed a homogeneous round shape with the mean particle size of around 13.73 ± 0.02 nm, polydisperse index (PDI) of 0.19 ± 0.01 and solubilizing efficiency of 95.7% ± 2.4%. In vitro and in vivo studies showed that HS 15-ARE is a stable injection presenting the same pharmacokinetic profile with CA-ARE. Moreover, improved therapeutic effect was observed for HS 15-ARE in treating asthma compared to CA-ARE (p < 0.05) with no anaphylactic reactions observed. These results demonstrate that the new formulation of ARE (HS 15-ARE) has a great potential for replacing CA-AREs injections.

Innate immunity in allergic disease

The innate immune system consists of multiple cell types that express germline-encoded pattern recognition receptors that recognize pathogen-associated molecular patterns (PAMPs) or danger-associated molecular patterns (DAMPs). Allergens are frequently found in forms and mixtures that contain PAMPs and DAMPs. The innate immune system is interposed between the external environment and the internal acquired immune system. It is also an integral part of the airways, gut, and skin. These tissues face continuous exposure to allergens, PAMPs, and DAMPs. Interaction of allergens with the innate immune system normally results in immune tolerance but, in the case of allergic disease, this interaction induces recurring and/or chronic inflammation as well as the loss of immunologic tolerance. Upon activation by allergens, the innate immune response commits the acquired immune response to a variety of outcomes mediated by distinct T-cell subsets, such as T-helper 2, regulatory T, or T-helper 17 cells. New studies highlighted in this review underscore the close relationship between allergens, the innate immune system, and the acquired immune system that promotes homeostasis versus allergic disease.

Anaphylactic reactions on the beach: a cause for concern?

BACKGROUND

The commonest causes of anaphylaxis include hymenoptera bites, high-risk food, exercise, and jellyfish bites and may often be encountered on the beach. Therefore, millions of visitors at popular touristic locations are exposed to increased risk of anaphylactic reactions every year. At least 35 cases of acute allergic reactions requiring medical attention took place on the beaches of Crete, Greece during the previous summer.

OBJECTIVE

To evaluate the level of training of lifeguards working on the beaches of the island of Crete, Greece, with regard to emergency management of anaphylaxis as well as to assess the sufficiency of medical equipment that lifeguards possess to treat an anaphylactic reaction.

METHODS

A questionnaire was prepared by the authors and administered to 50 lifeguards working on various beaches of Crete. Queries included the definition of anaphylaxis, proper medical treatment, and the existence or not and composition of an emergency kit with regard to the management of acute allergic reactions.

RESULTS

Our series consisted of 50 lifeguards, 39 (78%) male and 11 female (22%). Although 41 (80%) lifeguards were aware of an acceptable definition of anaphylaxis, no one knew that epinephrine is the first-choice treatment, and 32 (60%) lifeguards replied that steroids should be used for emergency treatment. Additionally, no one possessed an emergency kit that would qualify for management of acute allergic reactions.

CONCLUSIONS

The beach should be considered as a high-risk place for the appearance of anaphylactic reactions. Lifeguards who would be the first trained personnel to encounter this condition should be sufficiently trained and equipped for emergency treatment. Our department is currently introducing a training program to local authorities for the proper training and equipping of lifeguards in the island of Crete.

The roles of mast cells and Kupffer cells in rat systemic anaphylaxis

Mast cells and other cells such as macrophages have been shown to mediate systemic anaphylaxis. We determined the roles of mast cells and Kupffer cells in hepatic and systemic anaphylaxis of rats. Roles of mast cells were examined by using the mast cell-deficient white spotting (Ws/Ws) rat; the Ws/Ws and wild type (+/+) rats were sensitized with ovalbumin (1 mg). Roles of Kupffer cells were examined by depleting Kupffer cells using gadolinium chloride or liposome-encapsulated dichloromethylene diphosphonate in the Ws/Ws and Sprague-Dawley rats. An intravenous injection of 0.6 mg ovalbumin caused substantial anaphylactic hypotension in both the Ws/Ws and +/+ rats; however, the occurrence was delayed in the Ws/Ws rats. After antigen, portal venous pressure increased by 13.1 cmH2O in the +/+ rats, while it increased only by 5.7 cmH2O in the Ws/Ws rats. In response to antigen, the isolated perfused liver of the Ws/Ws rats also showed weak venoconstriction, the magnitude of which was one tenth as large as that of the +/+ rats, indicating that hepatic anaphylaxis was primarily due to mast cells. In contrast, Kupffer cell depletion did not attenuate anaphylactic hepatic venoconstriction in isolated perfused livers. In conclusion, mast cells are involved mainly in anaphylactic hepatic presinusoidal portal venoconstriction but only in the early stage of anaphylactic systemic hypotension in rats. Macrophages, including Kupffer cells, do not participate in rat hepatic anaphylactic venoconstriction.

Incidence and characteristics of biphasic anaphylaxis: a prospective evaluation of 103 patients

BACKGROUND

Although it is known that anaphylaxis can follow a biphasic course, reports of its incidence are conflicting. Furthermore, little is known about predictors of biphasic reactivity.

OBJECTIVE

To describe the incidence and characteristics of biphasic anaphylaxis occurring in a Canadian tertiary care center.

METHODS

All patients with emergency department visits and inpatients given a diagnosis of "allergic reaction" or "anaphylaxis" during a 3-year period were evaluated. Patients were contacted within 72 hours to establish symptoms and determine the presence of biphasic reactivity. A full medical record review ensued, and uniphasic and biphasic cases were compared using the Mann-Whitney U test for continuous data and the chi2 and Fisher exact tests for ordinal data.

RESULTS

A total of 134 patients with anaphylaxis were identified; complete follow-up was obtained for 103 patients. Twenty patients (19.4%) experienced confirmed biphasic reactivity. Average time to onset of the second phase was 10 hours (range, 2-38 hours); 8 patients (40.0%) had their second phase occur more than 10 hours after the initial reaction. The clinical presentations and histories of uniphasic and biphasic reactors were similar. Time to resolution of initial symptoms was significantly longer for biphasic reactors (112 vs 133 minutes; P = .03). Differences in management were noted: biphasic reactors received less epinephrine (P = .048) and tended to receive less corticosteroid (P = .06).

CONCLUSIONS

Biphasic reactivity occurred with an incidence of 19.4%, consistent with first descriptions. The second-phase onset was 10 hours on average, but it occurred as late as 38 hours. Biphasic anaphylaxis may be related, in part, to undertreatment.

Expanded bed adsorption as a fast technique for the large-scale purification of the complete isoform pool of Ber e 1, the major allergen from Brazil nuts

A new, fast, large-scale purification method for Ber e 1, the major allergen from Brazil nuts, using expanded bed adsorption (EBA) chromatography, is presented. Using EBA, crude extracts can be applied to a fluidized column, which allows the unhindered passage of particulate impurities, thereby avoiding time-consuming centrifugation or filtration steps. With this new purification method, 2.8 g of Ber e 1 was obtained from 85 g defatted Brazil nut meal, essentially within 1 day. Various structural as well as immunochemical characteristics of the purified protein were determined, and compared to those of Ber e 1 purified using conventional chromatographic techniques. The complete pool of Ber e 1 isoforms was collected using EBA. The most abundant isoforms were observed to have pI around 8 and heterogeneity was observed in both the large and the small subunit of the heterodimeric protein. Ber e 1 has a highly ordered secondary structure. No apparent differences in immune reactivity were observed between EBA purified Ber e 1 and conventionally purified Ber e 1, using IgE-binding experiments. Thus, using EBA, Ber e 1 can be purified fast and on gram-scale, while having purity equal to that of conventionally purified Ber e 1.

Allergenic characteristics of a modified peanut allergen

Attempts to treat peanut allergy using traditional methods of allergen desensitization are accompanied by a high risk of anaphylaxis. The aim of this study was to determine if modifications to the IgE-binding epitopes of a major peanut allergen would result in a safer immunotherapeutic agent for the treatment of peanut-allergic patients. IgE-binding epitopes on the Ara h 2 allergen were modified, and modified Ara h 2 (mAra h 2) protein was produced. Wild-type (wAra h 2) and mAra h 2 proteins were analyzed for their ability to interact with T-cells, their ability to bind IgE, and their ability to release mediators from a passively sensitized RBL-2H3 cell line. Multiple T-cell epitopes were identified on the major peanut allergen, Ara h 2. Ara h 2 amino acid regions 11-35, 86-125, and 121-155 contained the majority of peptides that interact with T-cells from most patients. The wAra h 2 and mAra h 2 proteins stimulated proliferation of T-cells from peanut-allergic patients to similar levels. In contrast, the mAra h 2 protein exhibited greatly reduced IgE-binding capacity compared to the wild-type allergen. In addition, the modified allergen released significantly lower amounts of beta-hexosaminidase, a marker for IgE-mediated RBL-2H3 degranulation, compared to the wild-type allergen.

Rapid recovery from acoustic trauma: chicken soup, potato knish, or drug interaction?

OBJECTIVES

To describe the phenomenology and consider possible mechanisms mediating rapid and unexpected recovery from acoustic trauma after ingestion of a food substance (potato knish).

STUDY DESIGN

Single subject with repeated test measures.

SETTING

Regional Veteran's Administration Medical Center, tertiary care medical center.

METHODS

Pure-tone audiometry and distortion product otoacoustic emissions (DPOAEs) performed at 6 days, 21 days, and 1 year postexposure.

RESULTS

Medical treatment with corticosteriods and a diuretic alone failed to improve auditory function and related symptoms (tinnitus and aural fullness) over a 2-week period. Rapid recovery of auditory function (dramatic improvement in pure tone thresholds; reappearance of DPOAEs) and abatement of related symptoms directly followed physiologic reactions from ingesting a food substance.

CONCLUSIONS

Rapid recovery from acoustic trauma was temporally correlated with urodynamic and cardiovascular reactions from ingesting food containing sulfite preservative, a substance to which the individual was allergic. Factors that may have contributed to recovery of function include massive diuresis, increased heart rate, release of biochemical mediators, mediator-induced vasodilatation, and changes in vascular or cell membrane permeability. Establishing relationships that lead to recovery of function from acoustic trauma may facilitate research and aid in the development of new treatment options for this condition.

Protein structure plays a critical role in peanut allergen stability and may determine immunodominant IgE-binding epitopes

Hypersensitivity to peanuts is a reaction mediated by IgE Abs in response to several peanut protein allergens. Among these allergenic proteins, Ara h 2 is one of the most commonly recognized allergens. Ara h 2 is a 17-kDa protein that has eight cysteine residues that could form up to four disulfide bonds. Circular dichroism studies showed substantial changes in the secondary and tertiary structures of the reduced Ara h 2 as compared with the native protein. Upon treatment with trypsin, chymotrypsin, or pepsin, a number of relatively large fragments are produced that are resistant to further enzymatic digestion. These resistant Ara h 2 peptide fragments contain intact IgE-binding epitopes and several potential enzyme cut sites that are protected from the enzymes by the compact structure of the protein. The enzyme-treated allergen remains essentially intact despite the action of proteases until the fragments are dissociated when the disulfide linkages are reduced. Amino acid sequence analysis of the resistant protein fragments indicates that they contain most of the immunodominant IgE-binding epitopes. These results provide a link between allergen structure and the immunodominant IgE-binding epitopes within a population of food-allergic individuals.

Pathways of anaphylaxis in the mouse

BACKGROUND

Although anaphylaxis is classically mediated by IgE, FcepsilonRI, mast cells, and histamine, several rodent studies suggest that an alternative pathway involving IgG, FcgammaRIII, macrophages and platelets, and platelet-activating factor (PAF) may be more important in the anaphylactic response to antigen challenge.

OBJECTIVES

We sought to determine the relative roles of the classical and alternative pathways of anaphylaxis in a mouse model characterized by mastocytosis and a high level of antigen-specific IgE antibody.

METHODS

Wild-type, IgE-deficient, FcepsilonRI-deficient, and mast cell-deficient mice were immunized with goat anti-mouse IgD antibody, which induces mastocytosis and a large IgE and IgG anti-goat IgG response, and then challenged 14 days later with antigen (goat IgG) or rat anti-mouse IgE mAb. Specific vasoactive mediators, cell types, Ig isotypes, or Ig receptors were blocked or eliminated before challenge in some experiments. The severity of anaphylaxis was gauged by changes in body temperature, physical activity, and mortality.

RESULTS

Equal doses of antigen or anti-IgE mAb induced similar anaphylactic responses. Anti-IgE mAb-induced anaphylaxis was FcepsilonRI and mast cell dependent and mediated predominantly by histamine. In contrast, neither mast cells nor platelets appeared important for antigen-induced anaphylaxis, which was FcgammaRIII and macrophage dependent and mediated predominantly by PAF.

CONCLUSIONS

Antigen-induced anaphylaxis in the mouse proceeds primarily through the IgG, FcgammaRIII, macrophage, and PAF pathway, even in an experimental model that is characterized by strong mast cell and IgE responses. The presence of FcgammaRIII on human macrophages makes it possible that the IgG, FcgammaRIII, macrophage, and PAF pathway also contributes to human anaphylaxis.

Food-dependent exercise-induced anaphylaxis

Food-dependent exercise-induced anaphylaxis (FDEIA) is a specific variant of exercise-induced anaphylaxis that requires both vigorous physical activity and the ingestion of specific foods within the preceding several hours. When patients present to the emergency department (ED) with allergic reactions, careful history regarding these 2 factors is required to establish the correct diagnosis. Correct diagnosis of FDEIA will allow patients to take control of their lifestyles and avert repeated events and ED visits. Two cases of FDEIA are presented, and the diagnosis, pathophysiology and therapy of food-dependent exercise-induced anaphylaxis are reviewed.