Risk assessment in anaphylaxis: current and future approaches

Venom immunotherapy in patients with mastocytosis and hymenoptera venom anaphylaxis

Systemic mastocytosis (SM) is typically suspected in patients with cutaneous mastocytosis (CM). In recent years, the presence of clonal mast cells (MCs) in a subset of patients with systemic symptoms associated with MC activation in the absence of CM has been reported and termed monoclonal MC activation syndromes or clonal systemic MC activation syndromes. In these cases, bone marrow (BM) MC numbers are usually lower than in SM with CM, there are no detectable BM MC aggregates, and serum baseline tryptase is often <20 µg/l; thus, diagnosis of SM in these patients should be based on careful evaluation of other minor WHO criteria for SM in reference centers, where highly sensitive techniques for immunophenotypic analysis and investigation of KIT mutations on fluorescence-activated cell sorter-purified BM MCs are routinely performed. The prevalence of hymenoptera venom anaphylaxis (HVA) among SM patients is higher than among the normal population and it has been reported to be approximately 5%. In SM patients with IgE-mediated HVA, venom immunotherapy is safe and effective and it should be prescribed lifelong. Severe adverse reactions to hymenoptera stings or venom immunotherapy have been associated with increased serum baseline tryptase; however, presence of clonal MC has not been ruled out in most reports and thus both SM and clonal MC activation syndrome might be underdiagnosed in such patients. In fact, clonal BM MC appears to be a relevant risk factor for both HVA and severe reactions to venom immunotherapy, while the increase in serum baseline tryptase by itself should be considered as a powerful surrogate marker for anaphylaxis. The Spanish Network on Mastocytosis has developed a scoring system based on patient gender, the clinical symptoms observed during anaphylaxis and serum baseline tryptase to predict for the presence of both MC clonality and SM among individuals who suffer from anaphylaxis.

An increase in serum tryptase even below 11.4 ng/mL may indicate a mast cell-mediated hypersensitivity reaction: a prospective study in Hymenoptera venom allergic patients

BACKGROUND

During a systemic hypersensitivity reaction (SR), an increase in serum tryptase compared to the baseline value is an indicator of mast cell activation, most often due to an IgE-mediated mechanism.

OBJECTIVE

To study the relevance of an increase in serum tryptase below the upper normal value of 11.4 ng/mL.

METHODS

Serum tryptase levels were measured in 35 patients with Hymenoptera venom hypersensitivity before and during venom exposure. Of these, 20 developed SR to stings or following venom injections during immunotherapy (reactors), while 15 tolerated reexposure to stings or venom injections during immunotherapy without SR (non-reactors). Serum tryptase was estimated at 2, 5 and 24 h after exposure and was compared to a baseline value obtained before or at least 72 h after exposure.

RESULTS

Considering circadian variation of serum tryptase, a relative increase to ≥135% of the baseline value (relative delta bound) was defined to indicate mast cell activation. Such an increase was observed in 17 of 20 reactors (85%), but none of 15 non-reactors. A serum tryptase of ≥11.4 ng/mL following venom exposure was observed in eight of the 20 reactors (40%) and 2 (13.3%) of the 15 non-reactors. Both these non-reactors also had an elevated baseline serum tryptase.

CONCLUSIONS AND CLINICAL RELEVANCE

Serum tryptase values obtained during a suspected hypersensitivity reaction must always be compared to a baseline value. A relative tryptase increase to ≥135% of the baseline value during a suspected hypersensitivity reaction indicates mast cell activation even below 11.4 ng/mL.

Food-induced anaphylaxis

PURPOSE OF REVIEW

Food-induced anaphylaxis is the leading single cause of anaphylaxis treated in emergency departments and increasing in prevalence.

RECENT FINDINGS

Food allergy is an increasing problem in westernized countries around the world, with a cumulative prevalence of 3-6%. Peanut, tree nuts, and shellfish are the most commonly implicated foods in anaphylaxis, although milk is a common trigger in children. Asthmatics, adolescents, and those with a prior reaction are at increased risk for more severe reactions. Most first reactions and reactions in children most commonly occur at home, whereas most subsequent reactions and reactions in adults occur outside home. Studies on schools have identified inadequate management plans and symptom recognition whereas those on restaurants report lack of prior notification by allergic individuals and lack in staff education. Epinephrine, although underutilized is the drug of choice with multiple doses needed in up to one-fifth of reactions. Diagnosis is currently based on convincing history and allergy testing supported by elevated serum tryptase, if available. Long-term management includes strict avoidance and emergency action plan.

SUMMARY

With a growing population of food-allergic children and adults, markers to predict which individuals are at increased risk for anaphylaxis as well as new therapies are vigorously sought.

Distinct immune effector pathways contribute to the full expression of peanut-induced anaphylactic reactions in mice

BACKGROUND

Food-induced anaphylaxis is often a severe allergic reaction characterized by multiorgan dysfunction and a potentially fatal outcome.

OBJECTIVES

We sought to investigate the relative contribution of immunoglobulin-dependent effector pathways to anaphylactic responses to food (ie, peanut).

METHODS

Wild-type and various mutant mice were sensitized with peanut protein and cholera toxin by means of oral gavage weekly for 4 weeks. Mice were subjected to different cellular depletion and Fc receptor blocking strategies before challenge with peanut 1 week after the last sensitization.

RESULTS

Our data indicate that pathways other than the classical mast cell (MC)-IgE pathway contribute to the full spectrum of anaphylactic reactions to peanut. We show that the single deletion of MCs, basophils, or phagocytes (ie, macrophages) prevents the most significant clinical outcome: death. Remarkably, the combined deficiency of MCs and phagocytes, but not MCs and basophils, averted nearly all clinical and physiological signs of anaphylaxis. Furthermore, blockade of both IgE and IgG1 signaling was necessary to abolish anaphylactic responses to peanut. Although MC responses occurred through IgE and IgG1, phagocyte responses were fully mediated through IgG1.

CONCLUSIONS

Peanut-induced anaphylaxis is a process that involves the concerted action of multiple immune effector pathways, and thus interventions targeting a single pathway (eg, MC-IgE) might not be sufficient to fully prevent anaphylactic responses.

Identification of markers that distinguish IgE- from IgG-mediated anaphylaxis

IgG-mediated anaphylaxis occurs in mice and may contribute to human reactions to infused drugs. To distinguish IgE- from putative IgG-mediated human anaphylaxis, we developed blood markers for murine anaphylaxis and evaluated their human relevance. Both IgG- and IgE-mediated anaphylaxis were characterized by decreased basophil and monocyte percentages and an increased neutrophil percentage in mouse blood. IgE- but not IgG-mediated murine anaphylaxis was accompanied by large increases in IL-4 secretion, plasma soluble IL-4 receptor-α (IL-4Rα) concentration, and T-cell membrane IL-4Rα expression. T-cell IL-4Rα expression also increased when mice that express human Fcε receptor Iα were sensitized with IgG-depleted serum from a peanut-allergic individual and challenged with peanut extract. Increased T-cell IL-4Rα expression is likely to also be a marker for human IgE-mediated anaphylaxis, because IgE-activated human basophils secrete IL-4, and IL-4 increases human T-cell IL-4Rα expression in vitro. Murine IgG- but not IgE-mediated anaphylaxis was characterized by decreased neutrophil Fcγ receptor III (FcγRIII) expression that was observed even when the antigen dose was insufficient to induce shock. Human neutrophils cultured with IgG immune complexes also lost FcγRIII. These observations suggest that decreased blood neutrophil FcγRIII expression without increased IL-4Rα expression can be used to determine whether and when IgG-mediated anaphylaxis occurs in man.

An intravenous exposure mouse model for prediction of potential drug-sensitization using reporter antigens popliteal lymph node assay

Immune-mediated drug hypersensitivity is a particularly concerning health-safety issue among clinicians given its unpredictability and potentially life-threatening effects, especially with exposure to intravenous drugs. Therefore, the development of intravenous drug-exposure models for drug-hazard assessments has garnered increasing interest in recent years. In this study, we used reporter antigens popliteal lymph node assay to investigate the potential value of intravenous exposure to a selected variety of allergenic compounds, including ovalbumin (OVA), concanavalin A (ConA) and diclofenac. The trinitrophenyl (TNP)-specific antibody-forming cells were used to assess the systemic immune responses to a bystander antigen. Mice were subsequently sensitized by TNP-OVA, and then intravenous exposure to one of the selective compounds. As expected, all positive compounds induced significant popliteal lymph node (PLN) proliferation compared with the control. OVA significantly increased Cluster of Differentiation 4 receptors (CD⁴)⁺ interleukin-4 (IL-4)⁺ T-helper 2 (Th2) cells and, consequently, increased the ratios of IL-4/interferon-γ (IFN-γ) antibody-forming cells (AFCs) in PLNs, while bringing about a dose-dependent increase in immunoglobulin G1 (IgG1) AFCs; these findings indicate that a Th2 hypersensitivity response was induced. A Th2 response was also observed in diclofenac sodium-treated groups, and for ConA, a more mixed Th1/Th2 immune response appeared to be induced. In addition, there was no marked reaction with the negative compound. Together, it seems likely that the intravenous exposure model may be useful for drug-induced systemic hypersensitivity assessments.

Peri-operative anaphylaxis

Peri-operative anaphylaxis is an important cause for mortality and morbidity associated with anaesthesia. The true incidence is unknown and is most likely under reported. Diagnosis can be difficult, particularly as a number of drugs are given simultaneously and any of these agents can potentially cause anaphylaxis. This review covers the clinical features, differential diagnosis and management of anaphylaxis associated with anaesthesia. The investigations to confirm the clinical suspicion of anaphylaxis and further tests to identify the likely drug(s) are examined. Finally the salient features of common and rare causes including non-drug substances are described.

Gene expression analysis predicts insect venom anaphylaxis in indolent systemic mastocytosis

BACKGROUND

Anaphylaxis to insect venom (Hymenoptera) is most severe in patients with mastocytosis and may even lead to death. However, not all patients with mastocytosis suffer from anaphylaxis. The aim of the study was to analyze differences in gene expression between patients with indolent systemic mastocytosis (ISM) and a history of insect venom anaphylaxis (IVA) compared to those patients without a history of anaphylaxis, and to determine the predictive use of gene expression profiling.

METHODS

Whole-genome gene expression analysis was performed in peripheral blood cells.

RESULTS

Twenty-two adults with ISM were included: 12 with a history of IVA and 10 without a history of anaphylaxis of any kind. Significant differences in single gene expression corrected for multiple testing were found for 104 transcripts (P < 0.05). Gene ontology analysis revealed that the differentially expressed genes were involved in pathways responsible for the development of cancer and focal and cell adhesion suggesting that the expression of genes related to the differentiation state of cells is higher in patients with a history of anaphylaxis. Based on the gene expression profiles, a naïve Bayes prediction model was built identifying patients with IVA.

CONCLUSIONS

In ISM, gene expression profiles are different between patients with a history of IVA and those without. These findings might reflect a more pronounced mast cells dysfunction in patients without a history of anaphylaxis. Gene expression profiling might be a useful tool to predict the risk of anaphylaxis on insect venom in patients with ISM. Prospective studies are needed to substantiate any conclusions.

Guidelines for the diagnosis and management of food allergy in the United States: report of the NIAID-sponsored expert panel

Food allergy is an important public health problem that affects children and adults and may be increasing in prevalence. Despite the risk of severe allergic reactions and even death, there is no current treatment for food allergy: the disease can only be managed by allergen avoidance or treatment of symptoms. The diagnosis and management of food allergy also may vary from one clinical practice setting to another. Finally, because patients frequently confuse nonallergic food reactions, such as food intolerance, with food allergies, there is an unfounded belief among the public that food allergy prevalence is higher than it truly is. In response to these concerns, the National Institute of Allergy and Infectious Diseases, working with 34 professional organizations, federal agencies, and patient advocacy groups, led the development of clinical guidelines for the diagnosis and management of food allergy. These Guidelines are intended for use by a wide variety of health care professionals, including family practice physicians, clinical specialists, and nurse practitioners. The Guidelines include a consensus definition for food allergy, discuss comorbid conditions often associated with food allergy, and focus on both IgE-mediated and non-IgE-mediated reactions to food. Topics addressed include the epidemiology, natural history, diagnosis, and management of food allergy, as well as the management of severe symptoms and anaphylaxis. These Guidelines provide 43 concise clinical recommendations and additional guidance on points of current controversy in patient management. They also identify gaps in the current scientific knowledge to be addressed through future research.

World allergy organization guidelines for the assessment and management of anaphylaxis

The illustrated World Allergy Organization (WAO) Anaphylaxis Guidelines were created in response to absence of global guidelines for anaphylaxis. Uniquely, before they were developed, lack of worldwide availability of essentials for the diagnosis and treatment of anaphylaxis was documented. They incorporate contributions from more than 100 allergy/immunology specialists on 6 continents. Recommendations are based on the best evidence available, supported by references published to the end of December 2010. The Guidelines review patient risk factors for severe or fatal anaphylaxis, co-factors that amplify anaphylaxis, and anaphylaxis in vulnerable patients, including pregnant women, infants, the elderly, and those with cardiovascular disease. They focus on the supreme importance of making a prompt clinical diagnosis and on the basic initial treatment that is urgently needed and should be possible even in a low resource environment. This involves having a written emergency protocol and rehearsing it regularly; then, as soon as anaphylaxis is diagnosed, promptly and simultaneously calling for help, injecting epinephrine (adrenaline) intramuscularly, and placing the patient on the back or in a position of comfort with the lower extremities elevated. When indicated, additional critically important steps include administering supplemental oxygen and maintaining the airway, establishing intravenous access and giving fluid resuscitation, and initiating cardiopulmonary resuscitation with continuous chest compressions. Vital signs and cardiorespiratory status should be monitored frequently and regularly (preferably, continuously). The Guidelines briefly review management of anaphylaxis refractory to basic initial treatment. They also emphasize preparation of the patient for self-treatment of anaphylaxis recurrences in the community, confirmation of anaphylaxis triggers, and prevention of recurrences through trigger avoidance and immunomodulation. Novel strategies for dissemination and implementation are summarized. A global agenda for anaphylaxis research is proposed.

Changes in gene expression caused by insect venom immunotherapy responsible for the long-term protection of insect venom-allergic patients

BACKGROUND

Insect venom immunotherapy (VIT) is the only causative treatment of insect venom allergy (IVA). The immunological mechanism(s) responsible for long-term protection achieved by VIT are largely unknown. A better understanding is relevant for improving the diagnosis, prediction of anaphylaxis, and monitoring and simplifying treatment of IVA.

OBJECTIVE

To find genes that are differentially expressed during the maintenance phase of VIT and after stopping, to get clues about the pathways involved in the long-term protective effect of immunotherapy.

METHODS

Whole genome gene expression analysis was performed on RNA samples from 50 patients treated with VIT and 43 healthy controls. Patients were divided into three groups: (1) before the start of VIT; (2) on maintenance phase of VIT for at least 3 years still receiving injections; and (3) after VIT.

RESULTS

Of all 48,804 probes present in the array, 48,773 transcripts had sufficient data for further analysis. The list of genes that were differentially expressed (at least log2 FC > 2; P < .05 corrected for multiple testing) during the maintenance phase of VIT as well as after successful VIT contains 89 entities. The function of these genes affects cell signaling, cell differentiation, and ion transport.

CONCLUSION

This study shows that a group of genes is differentially expressed both during and after VIT in comparison with gene expression in patients before VIT. Although the results of this study should be confirmed prospectively, the relevance of these findings is supported by the fact that they are related to putative mechanisms of immunotherapy.

Increased susceptibility of 129SvEvBrd mice to IgE-Mast cell mediated anaphylaxis

Background

Experimental analyses have identified strain-dependent factors that regulate susceptibility to anaphylaxis in mice. We assessed the susceptibility of the widely used 129SvEvBrd (also known as 129S5) mouse strain to IgE/mast cell-mediated anaphylaxis as compared to BALB/c. Mice were subjected to passive and oral Ovalbumin [OVA]-induced active anaphylaxis. Tissue mast cell, plasma histamine, total IgE and OVA-specific IgE levels and susceptibility to histamine i.v infusion were assessed. Bone marrow mast cell (BMMC)s were examined for Fc_εRI, c-kit, degranulation efficiency, proliferation, apoptosis and cytokine profile.

Results

129S5 mice had significantly increased susceptibility to passive and oral OVA-induced active anaphylaxis. Increased susceptibility to anaphylaxis was associated with increased homeostatic mast cell levels but not OVA-specific IgE or IgG₁ levels. In vitro analyses of BMMCs revealed no difference in Fc_εRI and c-Kit expression, however, 129S5 BMMCs possessed greater proliferative capacity and reduced caspase-3-mediated apoptosis. IgE-BMMC degranulation assays demonstrated no difference in degranulation efficiency. Furthermore, 129S5 mice possessed increased sensitivity to histamine-induced hypothermia.

Conclusions

We conclude that 129S5 mice have increased susceptibility to anaphylaxis as compared to BALB/c strain and their increased susceptibility was associated with altered mast cell proliferation and homeostatic tissue levels and responsiveness to histamine. Given the wide spread usage of the 129SvEvBrd strain of mice in experimental gene targeting methodology, these data have important implications for studying IgE-reactions in mouse systems.

Anaphylaxis in Latin America: a report of the online Latin American survey on anaphylaxis (OLASA)

OBJECTIVES

The aims of the Online Latin American Survey of Anaphylaxis (OLASA) were to identify the main clinical manifestations, triggers, and treatments of severe allergic reactions in patients who were seen by allergists from July 2008 to June 2010 in 15 Latin American countries and Portugal (n =634).

RESULTS

Of all patients, 68.5% were older than 18 years, 41.6% were male, and 65.4% experienced the allergic reaction at home. The etiologic agent was identified in 87.4% of cases and predominantly consisted of drugs (31.2%), foods (23.3%), and insect stings (14.9%). The main symptom categories observed during the acute episodes were cutaneous (94.0%) and respiratory (79.0%). The majority of patients (71.6%) were treated initially by a physician (office/emergency room) within the first hour after the reaction occurred (60.2%), and 43.5% recovered in the first hour after treatment. Most patients were treated in an emergency setting, but only 37.3% received parenteral epinephrine alone or associated with other medication. However, 80.5% and 70.2% were treated with corticosteroids or antihistamines (alone or in association), respectively. A total of 12.9% of the patients underwent reanimation maneuvers, and 15.2% were hospitalized. Only 5.8% of the patients returned to the emergency room after discharge, with 21.7% returning in the first 6 hours after initial treatment.

CONCLUSION

The main clinical manifestations of severe allergic reactions were cutaneous. The etiologic agents that were identified as causing these acute episodes differed according to age group. Following in order: drugs (31.2%), foods (23.3% and insect stings (14.9%) in adults with foods predominance in children. Treatment provided for acute anaphylactic reactions was not appropriate. It is necessary to improve educational programs in order to enhance the knowledge on this potentially fatal emergency.

Guidelines for the diagnosis and management of food allergy in the United States: report of the NIAID-sponsored expert panel

Food allergy is an important public health problem that affects children and adults and may be increasing in prevalence. Despite the risk of severe allergic reactions and even death, there is no current treatment for food allergy: the disease can only be managed by allergen avoidance or treatment of symptoms. The diagnosis and management of food allergy also may vary from one clinical practice setting to another. Finally, because patients frequently confuse nonallergic food reactions, such as food intolerance, with food allergies, there is an unfounded belief among the public that food allergy prevalence is higher than it truly is. In response to these concerns, the National Institute of Allergy and Infectious Diseases, working with 34 professional organizations, federal agencies, and patient advocacy groups, led the development of clinical guidelines for the diagnosis and management of food allergy. These Guidelines are intended for use by a wide variety of health care professionals, including family practice physicians, clinical specialists, and nurse practitioners. The Guidelines include a consensus definition for food allergy, discuss comorbid conditions often associated with food allergy, and focus on both IgE-mediated and non-IgE-mediated reactions to food. Topics addressed include the epidemiology, natural history, diagnosis, and management of food allergy, as well as the management of severe symptoms and anaphylaxis. These Guidelines provide 43 concise clinical recommendations and additional guidance on points of current controversy in patient management. They also identify gaps in the current scientific knowledge to be addressed through future research.

Anaphylaxis and insect allergy

PURPOSE OF REVIEW

Anaphylaxis is an acute-onset and potentially life-threatening allergic reaction that can be caused by numerous allergic triggers including stinging insects. This review focuses on recent advances, natural history, risk factors and therapeutic considerations.

RECENT FINDINGS

Recent work suggests that concerns over insect allergy diagnosis continue to exist. This is especially true with individuals who have a convincing history of a serious life-threatening anaphylactic event, but lack the necessary diagnostic criteria of venom-specific IgE by skin test or in-vitro diagnostic methods to confirm the diagnosis. The role of occult mastocytosis or increased basophile reactivity may play a role in this subset population. Additionally, epinephrine continues to be underutilized as the primary acute intervention for an anaphylactic reaction in the emergent setting.

SUMMARY

The incidence of anaphylaxis continues to rise across all demographic groups, especially those less than 20 years of age. Fortunately, the fatalities related to anaphylaxis appear to have decreased over the past decades. Our understanding of various triggers, associated risk factors, as well as an improved understanding and utilization of biological markers such as serum tryptase have improved. Our ability to treat insect anaphylaxis by venom immunotherapy is highly effective. Unfortunately, anaphylaxis continues to be underappreciated and undertreated especially in regard to insect sting anaphylaxis. This includes the appropriate use of injectable epinephrine as the primary acute management tool. These findings suggest that continued education of the general population, primary care healthcare providers and emergency departments is required.

Key components of anaphylaxis management plans: consensus findings from a national electronic Delphi study

Objectives

There is no international consensus on the components of anaphylaxis management plans and responsibility for their design and delivery is contested. We set out to establish consensus among relevant specialist and generalist clinicians on this issue to inform future randomized controlled trials.

Design

A two-round electronic Delphi study completed by a 25-person, multidisciplinary expert panel. Participants scored the importance of a range of statements on anaphylaxis management, identified from a systematic review of the literature, on a five-point scale ranging from ‘very important’ to ‘irrelevant’. Consensus was defined a priori as being achieved if 80% or more of panel members rated a statement as ‘important’ or ‘very important’ after Round 2.

Setting

Primary and secondary care and academic settings in the UK and Ireland.

Participants

Twenty-five medical, nursing and allied health professionals.

Main outcome measures

Consensus on the key components of anaphylaxis management plans.

Results

The response rate was 84% (n = 21) for Round 1 and 96% (n = 24) for Round 2. The key components of emergency care on which consensus was achieved included: awareness of trigger factors (100%); recognition and emergency management of reactions of different severity (100%); and clear information on adrenaline (epinephrine) use (100%). Consensus on longer-term management issues included: clear written guidelines on anaphylaxis management (96%); annual review of plans (87%); and plans that were tailored to individual needs (82%).

Conclusions

This national consensus-building exercise generated widespread agreement that emergency plans need to be simple, clear and generic, making them easy to implement in a crisis. In contrast, long-term plans need to be negotiated between patient/carers and professionals, and tailored to individual needs. The effectiveness of this expert-agreed long-term plan now needs to be evaluated rigorously.

The diagnosis and management of anaphylaxis practice parameter: 2010 update

These parameters were developed by the Joint Task Force on Practice Parameters, representing the American Academy of Allergy, Asthma & Immunology (AAAAI); the American College of Allergy, Asthma & Immunology (ACAAI); and the Joint Council of Allergy, Asthma and Immunology. The AAAAI and the ACAAI have jointly accepted responsibility for establishing "The Diagnosis and Management of Anaphylaxis Practice Parameter: 2010 Update." This is a complete and comprehensive document at the current time. The medical environment is a changing environment, and not all recommendations will be appropriate for all patients. Because this document incorporated the efforts of many participants, no single individual, including those who served on the Joint Task Force, is authorized to provide an official AAAAI or ACAAI interpretation of these practice parameters. Any request for information about or an interpretation of these practice parameters by the AAAAI or ACAAI should be directed to the Executive Offices of the AAAAI, the ACAAI, or the Joint Council of Allergy, Asthma and Immunology. These parameters are not designed for use by pharmaceutical companies in drug promotion.

World Allergy Organization survey on global availability of essentials for the assessment and management of anaphylaxis by allergy-immunology specialists in health care settings

BACKGROUND

The availability of anaphylaxis guidelines and of medications, supplies, and equipment for the assessment and management of anaphylaxis by allergy-immunology specialists in health care settings worldwide is unknown.

OBJECTIVE

To ascertain the global availability of these essentials.

METHODS

A survey instrument was developed and sent by e-mail in 2008 to a nonrandomized convenience sample of representative leading allergy-immunology specialists in 52 countries identified through the World Allergy Organization. Responses were analyzed by country.

RESULTS

Surveys were returned from 44 of 52 countries on 6 continents, for an 85% response rate. Anaphylaxis guidelines were reported to be in use in 70% of the 44 responding countries. The diagnosis of acute anaphylaxis was reported to be based on clinical history and physical examination alone in 63% of responding countries. Medications for anaphylaxis treatment were reported to be available in the 44 responding countries as follows: epinephrine (adrenaline) for injection, 100%; any intravenous glucocorticoid, 89%; any intravenous H1-antihistamine, 77%; any intravenous H2-antihistamine, 70%; glucagon, 73%; atropine, 73%; dopamine, 86%; noradrenaline, 70%; vasopressin, 64%; and a beta 2-agonist for nebulization, 86%. Supplies and equipment for anaphylaxis treatment were reported to be available in responding countries as follows: for giving supplemental oxygen, 95%; for intubation, 89%; for giving intravenous fluid resuscitation, 91%; for monitoring oxygenation using pulse oximetry, 91%; and for continuous noninvasive blood pressure and cardiac monitoring, 81%.

CONCLUSIONS

Allergy-immunology specialists reported that except for epinephrine ampules life-saving essentials for the assessment and management of anaphylaxis in health care settings were not universally available worldwide in 2008.

Are plasma IL-10 levels a useful marker of human clinical tolerance in peanut allergy?

Background

Food allergies are a major component of the burden of allergic disease. Accurate risk assessment for prediction of future clinical reactivity or clinical tolerance is limited by currently available techniques. Recent studies suggest that constitutively elevated global serum levels of IL-10, a cytokine that down-regulates both Th1 and Th2 cytokine production, may be useful in identifying human clinical tolerance to foods.

Objective

Determine the usefulness of constitutive IL-10 levels as a marker of clinical tolerance to peanut in children and adults.

Methodology/Principal Findings

107 subjects who were clinically tolerant to peanut and 94 subjects who were clinically allergic to peanut participated. Plasma was analyzed via ELISA to quantify the frequency of individuals with constitutive IL-10 levels and the intensity of those responses. The data were then stratified by age, gender and clinical status to assess the utility of this putative biomarker in specific at-risk groups. All 201 subjects had readily quantified plasma IL-10. Levels were no higher in subjects who were clinically tolerant to peanut than those in individuals clinically allergic to peanut. Stratification by age, gender or both did not improve the capacity of IL-10 levels to identify clinical tolerance to peanut.

Conclusions/Significance

Plasma IL-10 levels are neither a useful biomarker of clinical tolerance to peanut nor a potential tool for identification of clinical tolerance to peanut in humans.

Post-mortem diagnosis of anaphylaxis: A difficult task in forensic medicine

The lack of reliable laboratory biomarkers and common standard definitions of signs and symptoms represents the main problem for clinicians when a suspected anaphylactic event must be diagnosed, while a post-mortem diagnosis of anaphylaxis is often a very difficult task in forensic medicine. Significant necroscopic signs as well as the data reported from witnesses or medical records may be absent, biological fluids as blood or urine may be unavailable or under thanatological modifications. The aim of this review is to focus on the diagnostic difficulties with which coroners and forensic pathologists have to cope when a confirmation of anaphylactic death is required by judicial authorities. Investigation methods for a prudent forensic diagnosis of anaphylactic death as well as the need of new potential laboratory or histological investigation techniques coming from immunological research are discussed too.

Can the Brighton Collaboration case definitions be used to improve the quality of Adverse Event Following Immunization (AEFI) reporting? Anaphylaxis as a case study

The Brighton Collaboration (BC) was established in 2000 with the aim of developing globally accepted standardized case definitions for adverse events following immunizations (AEFI) as well as guidelines for the collection, analysis and presentation of surveillance data. Some of the BC case definitions are complex and this may limit their application for use in post-marketing vaccine surveillance. Barriers to the application of the BC case definitions include an incomplete description of an adverse event and inconsistencies in reporter use of adverse event terms. We have taken the BC case definition for anaphylaxis and developed a clinical checklist and glossary of terms used in the case definition. It is anticipated that these resources can be used at a community level by AEFI reporters. If used, these resources could improve the quality of adverse event reports which would facilitate the application of the BC case definition at a regional and/or national level.

Anaphylaxis in the obstetric patient: analysis of a statewide hospital discharge database

BACKGROUND

Previous reports of anaphylaxis during pregnancy typically have involved single institutions and a few cases.

OBJECTIVE

To describe the epidemiologic features of anaphylaxis in women who gave birth in Texas.

METHODS

Statewide public use hospital discharge data for 2004 and 2005 provided by the Texas Department of State Health Services were accessed. Diagnoses and procedures in this data set were recorded using International Classification of Diseases, Ninth Revision, Clinical Modification codes. The records of women who delivered a neonate and simultaneously had a diagnosis of anaphylaxis were selected for study. The prevalence of maternal anaphylaxis noted at the time of delivery of the neonate and the 95% Wilson's confidence interval were calculated. The International Classification of Diseases, Ninth Revision, Clinical Modification E codes were examined to determine the possible anaphylactic trigger. Finally, the impact of 4 selected maternal comorbidities and complications on length of stay was assessed.

RESULTS

A total of 19 maternal anaphylaxis cases were identified. The prevalence was 2.7 cases per 100,000 deliveries (95% confidence interval, 1.7-4.2 cases per 100,000 deliveries). Penicillins and cephalosporins were the anaphylactic trigger in 11 of the patients. Five patients were emergent admissions. There were no maternal deaths. Most of the patients (14 [74%]) delivered by cesarean section. Patients who had 1 or more of 4 selected comorbidities or complications had a median length of stay of 5 days, whereas those patients free of these conditions had a median length of stay of 3 days (P = .07, exact Wilcoxon rank sum test).

CONCLUSIONS

Anaphylaxis during pregnancy is a rare event. In this large case series, we found that beta-lactam antibiotics were the most common triggers of anaphylaxis.

Differential roles for the IL-9/IL-9 receptor alpha-chain pathway in systemic and oral antigen-induced anaphylaxis

BACKGROUND

The cytokine IL-9 has been implicated in allergic reactions, including food allergy, but its contribution to parenteral versus oral antigen-induced anaphylaxis remains unclear.

OBJECTIVES

We sought to delineate the contribution of the IL-9/IL-9 receptor alpha-chain (IL-9R) pathway to parenteral and oral antigen-induced anaphylaxis.

METHODS

Wild-type, IL-9-deficient (Il9(-/-)), and IL-9R-deficient (Il9R(-/-)) mice were subjected to passive and active parenteral and oral antigen (ovalbumin [OVA])-induced anaphylaxis. Severity of systemic anaphylaxis was gauged by decreased body temperature; intestinal anaphylaxis was assessed based on secretory diarrhea, intestinal mastocytosis, and serum murine mast cell protease 1 level. Specific immunoglobulin isotypes or immunoglobulin receptor-blocking antibodies were administered before challenge to define the role of the IgE and IgG pathways.

RESULTS

Repeated oral antigen challenge of OVA-sensitized wild-type mice induced anaphylaxis with both systemic and intestinal involvement; both were IgE dependent and attenuated in Il9(-/-) and Il9R(-/-) mice. In contrast, parenteral OVA challenge of OVA-sensitized wild-type mice induced systemic anaphylaxis, which was independent of the IL-9/IL-9R pathway. Strikingly, the IL-9/IL-9R pathway had no role in either the IgG or IgE component of parenteral antigen-induced or anti-IgE and anti-FcgammaRII/III mAb-induced systemic anaphylaxis.

CONCLUSIONS

Parenteral antigen-induced murine systemic anaphylaxis is mediated by both IgG- and IgE-dependent pathways, and both can occur independently of IL-9/IL-9R signaling. In contrast, oral antigen-induced intestinal and systemic anaphylaxis is strictly IgE mediated and requires IL-9/IL-9R signaling. These studies indicate differential involvement of the IL-9/IL-9R pathway in systemic and oral antigen-induced anaphylaxis.

A case of anaphylaxis after the ingestion of yacon

Anaphylaxis is a potentially life-threatening systemic allergic reaction, often with an explosive onset; the symptoms range from mild flushing to upper respiratory obstruction, with or without vascular collapse. Foods are common offending allergens and remain the leading cause of outpatient anaphylaxis in most surveys. Yacon (Smallanthus sonchifolius) is a plant native to the Andes region, where its root is cultivated and consumed mainly as food. Unlike most edible roots, yacon contains large amounts of ructooligosaccharides. Traditionally, yacon tubers have been used as a source of natural sweetener and syrup for people suffering from various disorders. We report the case of a 55-year-old woman who developed syncope and generalized urticaria after ingesting yacon roots. The patient had positive skin prick and intradermal tests to yacon extract. An open food challenge test was performed to confirm food anaphylaxis and was positive 10 minutes after the consumption of yacon roots. To our knowledge, this is the first reported case of anaphylaxis after the ingestion of yacon roots.

Profile of eicosanoid generation in aspirin-intolerant asthma and anaphylaxis assessed by new biomarkers

BACKGROUND

It has recently demonstrated that a free radical-mediated pathway generates prostaglandins (PGs) and the corresponding prostaglandin enantiomers (ent-PGs). Aspirin-intolerant asthma and anaphylaxis accompany PGD(2) overproduction, possibly associated with mast cell activation via the COX pathway. However, free radical-mediated PG generation in the pathophysiology of these diseases, which can be demonstrated by measuring urinary ent-PGF(2)alpha, has not been reported.

OBJECTIVES

To evaluate the characteristic profile of eicosanoid generation via the COX and/or free radical-mediated pathway underlying aspirin-intolerant asthma and anaphylaxis.

METHODS

A comparative group analysis consisted of asthma (n = 17) and anaphylaxis (n = 8, none with aspirin-induced anaphylaxis) cases. Urinary eicosanoid concentrations were quantified as follows: 2,3-dinor-9alpha,11beta-PGF(2) by gas chromatography-mass spectrometry; leukotriene E(4), 9alpha,11beta-PGF(2), and PGs by enzyme immunoassay.

RESULTS

2,3-Dinor-9alpha,11beta-PGF(2) is a more predominant PGD(2) metabolite in urine than 9alpha,11beta-PGF(2). At baseline, the aspirin-intolerant asthma group (n = 10) had significantly higher leukotriene E(4) and lower PGE(2) concentrations in urine than the aspirin-tolerant asthma group. During the reaction, the urinary concentrations of leukotriene E(4) and PGD(2) metabolites correlatively increased, but with markedly different patterns of the mediator release, in the aspirin-intolerant asthma group and the anaphylaxis group, respectively. The urinary PGD(2) metabolites and primary PGs were significantly decreased in the aspirin-tolerant asthma group. Urinary ent-PGF(2)alpha concentrations were significantly increased in the anaphylaxis group but not the aspirin-intolerant asthma group.

CONCLUSIONS

When assessed by urinary 2,3-dinor-9alpha,11beta-PGF(2), PGD(2) overproduction during aspirin-intolerant bronchoconstriction was clearly identified, regardless of COX inhibition. It is evident that free radical-mediated PG generation is involved in the pathophysiology of anaphylaxis.

Mast cell proteases: multifaceted regulators of inflammatory disease

Mast cells (MCs) are currently receiving increased attention among the scientific community, largely because of the recent identification of crucial functions for MCs in a variety of disorders. However, it is in many cases not clear exactly how MCs contribute in the respective settings. MCs express extraordinarily high levels of a number of proteases of chymase, tryptase, and carboxypeptidase A type, and these are stored in high amounts as active enzymes in the MC secretory granules. Hence, MC degranulation leads to the massive release of fully active MC proteases, which probably have a major impact on any condition in which MC degranulation occurs. Indeed, the recent generation and evaluation of mouse strains lacking individual MC proteases have indicated crucial contributions of these to a number of different disorders. MC proteases may thus account for many of the effects ascribed to MCs and are currently emerging as promising candidates for treatment of MC-driven disease. In this review, we discuss these findings.

Diagnostic utility of two case definitions for anaphylaxis: a comparison using a retrospective case notes analysis in the UK

Anaphylaxis is a clinical diagnosis with no gold-standard test. Recent case definitions have attempted to provide objective criteria for diagnosis. The aim of this study was to compare the diagnostic concordance of the Brighton Collaboration case definition (the 'Brighton' case definition) to the consensus case definition from the Second Symposium on the Definition and Management of Anaphylaxis (the 'Symposium' definition). The study setting was a hospital-based emergency department in the UK. We identified cases of anaphylaxis by physicians' discharge diagnoses over a 2-year period from 2005 to 2006, and used randomly selected cases of allergic reaction, asthma and urticaria as a control group. Data was extracted by clinicians (who were unaware of the content of either case definition), and the two case definitions were applied by Boolean operators in a Microsoft Excel spreadsheet. Concordance between the case definitions was measured using Cohen's kappa (kappa) statistic. We reviewed 128 sets of notes, with 47 cases of anaphylaxis. Brighton and Symposium definitions had sensitivities of 0.681 and 0.671, respectively, and specificities of 0.790 and 0.704, respectively. A discordant result was found in 36/128 cases (28.1%; kappa = 0.414 [95% CI 0.253, 0.574]), which represents a moderate level of agreement between case definitions. The Brighton case definition has a similar diagnostic concordance to the Symposium case definition. It does not seem to over- or underestimate cases and is sufficiently unique that the identification of an allergic trigger does not have to form part of the case definition. This will be important in the recognition of anaphylaxis resulting from the administration of drug and vaccines, where causality should be examined separately from case ascertainment.

Anaphylaxis: Recent advances in assessment and treatment

The incidence rate of anaphylaxis is increasing, particularly during the first 2 decades of life. Common triggers include foods, medications, and insect stings. Clinical diagnosis is based on a meticulous history of an exposure or event preceding characteristic symptoms and signs, sometimes but not always supported by a laboratory test such as an elevated serum total tryptase level. Physician-initiated investigation of patients with anaphylaxis whose symptoms and signs are atypical sometimes leads to important insights into previously unrecognized triggers and mechanisms. In idiopathic anaphylaxis, in which no trigger can be confirmed by means of skin testing or measurement of specific IgE, the possibility of mastocytosis or a clonal mast cell disorder must be considered in addition to the possibility of a previously unrecognized trigger. Long-term risk reduction in patients with anaphylaxis focuses on optimal management of relevant comorbidities such as asthma and other respiratory diseases, cardiovascular disease, and mastocytosis or a clonal mast cell disorder; avoidance of the relevant confirmed allergen trigger; and relevant immunomodulation such as medication desensitization, venom immunotherapy, and possibly in the future, immunotherapy with food. Emergency preparedness for recurrence of anaphylaxis in community settings includes having epinephrine (adrenaline) autoinjectors available, knowing when and how to use them, and having a written, personalized anaphylaxis emergency action plan and up-to-date medical identification. Randomized controlled trials of the pharmacologic interventions used in an acute anaphylaxis episode are needed.

Mechanisms of mast cell signaling in anaphylaxis

The recent development of a consensus definition and proposed diagnostic criteria for anaphylaxis offers promise for research efforts and a better understanding of the epidemiology and pathogenesis of this enigmatic and life-threatening disease. This review examines basic principles and recent research advances in the mechanisms of mast cell signaling believed to underlie anaphylaxis. The unfolding complexity of mast cell signaling suggests that the system is sensitive to regulation by any of several individual signaling pathways and intermediates and that complementary pathways regulate mast cell activation by amplified signals. The signaling events underlying anaphylactic reactions have largely been identified through experiments in genetically modified mice and supported by biochemical studies of mast cells derived from these mice. These studies have revealed that signaling pathways exist to both upregulate and downregulate mast cell responses. In this review we will thus describe the key molecular players in these pathways in the context of anaphylaxis.

How safe are the biologicals in treating asthma and rhinitis?

A number of biological agents are available or being investigated for the treatment of asthma and rhinitis. The safety profiles of these biologic agents, which may modify allergic and immunological diseases, are still being elucidated. Subcutaneous allergen immunotherapy, the oldest biologic agent in current use, has the highest of frequency of the most serious and life-threatening reaction, anaphylaxis. It is also one of the only disease modifying interventions for allergic rhinitis and asthma. Efforts to seek safer and more effective allergen immunotherapy treatment have led to investigations of alternate routes of delivery and modified immunotherapy formulations. Sublingual immunotherapy appears to be associated with a lower, but not zero, risk of anaphylaxis. No fatalities have been reported to date with sublingual immunotherapy. Immunotherapy with modified formulations containing Th1 adjuvants, DNA sequences containing a CpG motif (CpG) and 3-deacylated monophospholipid A, appears to provide the benefits of subcutaneous immunotherapy with a single course of 4 to 6 preseasonal injections. There were no serious treatment-related adverse events or anaphylaxis in the clinical trials of these two immunotherapy adjuvants. Omalizumab, a monoclonal antibody against IgE, has been associated with a small risk of anaphylaxis, affecting 0.09% to 0.2% of patients. It may also be associated with a higher risk of geohelminth infection in patients at high risk for parasitic infections but it does not appear to affect the response to treatment or severity of the infection.

Clinical trials with other biologic agents that have targeted IL-4/IL-13, or IL-5, have not demonstrated any definite serious treatment-related adverse events. However, these clinical trials were generally done in small populations of asthma patients, which may be too small for uncommon side effects to be identified. There is conflicting information about the safety TNF-alpha blocking agents, which have been primarily used in the treatment of rheumatoid arthritis, with serious infections, cardiovascular disease and malignancies being the most frequent serious adverse events. An unfavorable risk-benefit profile led to early discontinuation of a TNF-blocking agent in a double-blind placebo controlled of severe asthmatics.

In summary, the risk of anaphylaxis and other treatment-related serious events with of all of the biological agents in this review were relatively small. However, most of the clinical trials were done in relatively small patient populations and were of relatively short duration. Long term studies in large patient populations may help clarify the risk-benefit profile of these biologic agents in the treatment of asthma.

Associations of functional NLRP3 polymorphisms with susceptibility to food-induced anaphylaxis and aspirin-induced asthma

BACKGROUND

NLR family, pyrin domain containing 3 (NLRP3), controls the activity of inflammatory caspase-1 by forming inflammasomes, which leads to cleavage of the procytokines IL-1beta and IL-18. Recent studies have shown associations of human NLRP3 polymorphisms with susceptibility to various inflammatory diseases; however, the association with allergic diseases remains unclear.

OBJECTIVE

We sought to examine whether NLRP3 polymorphisms are associated with susceptibility to food allergy, food-induced anaphylaxis, and aspirin-induced asthma (AIA).

METHODS

We selected 15 tag single nucleotide polymorphisms (SNPs) of NLRP3 and conducted association analyses of NLRP3 using 574 and 1279 samples for food allergy and AIA, respectively. We further performed functional analyses of the susceptible SNPs.

RESULTS

Two NLRP3 SNPs (rs4612666 and rs10754558) were significantly associated with susceptibility to food-induced anaphylaxis (P = .00086 and P = .00068, respectively). The NLRP3 haplotype of the 2 SNPs also showed a significant association (P = .000098). We could confirm the association with susceptibility to another hypersensitivity phenotype, AIA (rs4612666, P = .0096). Functional analysis revealed that the risk alleles of rs4612666 and rs10754558 increased the enhancer activity of NLRP3 expression and NLRP3 mRNA stability, respectively.

CONCLUSION

Our results indicate that the NLRP3 SNPs might play an important role in the development of food-induced anaphylaxis and AIA in a gain-of-function manner. Further research on the NLRP3 inflammasome will contribute to the development of novel diagnostic and therapeutic methods for food-induced anaphylaxis and AIA.

Anaphylaxis in the community: learning from the survivors

BACKGROUND

Most studies of anaphylaxis in the community focus on persons at risk who might, or might not, have experienced anaphylaxis.

OBJECTIVE

We sought to focus on survivors of anaphylaxis in the community and their experiences in using, or not using, an epinephrine autoinjector for first-aid treatment.

METHODS

An e-mail survey was conducted. Responses were anonymous and could not be traced to any person or location. Anaphylaxis was defined as the most severe sudden-onset allergic reaction ever experienced by the participants or a person for whom they were responsible (eg, a child). There were 17 core multiple-choice questions for all participants, with 16 additional questions for users who injected epinephrine either into themselves or someone else, and 1 additional question for nonusers.

RESULTS

Of the 1885 participants, 500 (27%) were epinephrine users, and 1385 (73%) were nonusers. The groups were similar with regard to multisystem organ involvement (82% vs 78%, P = .07) and many other aspects of anaphylaxis; however, epinephrine users were more likely (all P < .05) to report respiratory or shock symptoms; to report peanut, fish, or insect sting triggers; to be asthmatic; and to have taken or been given asthma medication on the day of the episode. Epinephrine users reported problems in deciding whether to give the injection, repeat the dose, and/or go to an emergency department. Nonusers reported not injecting epinephrine for various reasons, including use of an H(1)-antihistamine (38%), no prescription for epinephrine (28%), and/or a mild anaphylaxis episode (13%).

CONCLUSIONS

In a unique population composed of 1885 survivors of anaphylaxis in the community, users of epinephrine autoinjectors for first-aid treatment were outnumbered by nonusers. The insights reported by epinephrine users and the reasons why nonusers did not inject epinephrine are documented.

Sphingosine-1-phosphate induces development of functionally mature chymase-expressing human mast cells from hematopoietic progenitors

Mast cells (MCs) play a critical role in both acute and chronic inflammation and mature in peripheral tissues from bone marrow-derived progenitors that circulate in the blood as immature precursors. MCs developed from cord blood-derived progenitors cultured with stem cell factor (SCF) alone express intragranular tryptase (MC(T)s), the phenotype predominant in the lung. MC progenitors are likely to encounter the serum-borne bioactive sphingolipid metabolite, sphingosine-1-phosphate (S1P), during migration to target tissues. S1P accelerated the development of cord blood-derived MCs (CB-MCs) and strikingly increased the numbers of MC-expressing chymase. These MCs have functional Fc epsilonRIs, and similar to skin MC(TC)s that express both tryptase and chymase, also express CD88 and are activated by anaphylatoxin C5a and the secretagogue compound 48/80. S1P induced release of IL-6, a cytokine known to promote development of functionally mature MC(TC)s, from cord blood cultures containing adherent macrophages, and from highly purified macrophages, but not from macrophage-depleted CB-MCs. In contrast, S1P stimulated secretion of the chemokine, monocyte chemoattractant protein 1 (MCP-1/CCL2), from these macrophage-depleted and purified CB-MCs. These results suggest crucial roles for S1P in regulating development of human MCs and their functions and reveal a complex interplay between macrophages and MC progenitors in the development of mature human MCs.

Understanding the mechanisms of anaphylaxis

PURPOSE OF REVIEW

The present review considers recent reports that identify the roles of key intermediate signaling components and mediators during and after mast cell activation and degranulation leading to anaphylaxis.

RECENT FINDINGS

Mechanisms of anaphylaxis are becoming better understood as the interaction of several regulatory systems in the mast cell activation and degranulation signaling cascade. Multiple tyrosine kinases, activated after immunoglobulin E binding to the high-affinity receptors for immunoglobulin E (FcepsilonRI), exert both positive and negative regulation on the signaling cascade, which may vary with genetic background or mutations in signaling proteins. Calcium influx, the essential, proximal intracellular event leading to mast cell degranulation, is controlled also by both negative and positive regulation through calcium channels. Sphingosine-1-phosphate is emerging as a newly realized mediator of anaphylaxis, acting as a signaling component within the mast cell and as a circulating mediator.

SUMMARY

Anaphylaxis is a systemic reaction involving multiple organ systems, but it is believed that it may be influenced by cellular events in mast cells and basophils resulting in the release of mediators. Therefore, understanding the mechanisms of mast cell activation and degranulation is critical to understanding the mechanisms of anaphylaxis. Recent reports have identified important regulatory components of the signaling cascade and, consequently, potential targets for therapeutic intervention.

The diagnosis of IgE-mediated food allergy in childhood

IgE-mediated food allergy is a common condition in childhood and a recognized public health concern. An accurate diagnosis of food allergy facilitates the avoidance of the allergen - and cross-reactive allergens - and allows for safe dietary expansion. The diagnosis of food allergy relies on a combination of rigorous history, physical examination, allergy tests [skin prick tests (SPT) and/or serum-specific IgE] and oral food challenges. Diagnostic cut-off values for SPT and specific IgE results have improved the diagnosis of food allergy and thereby reduced the need to perform oral food challenges. This clinical case series seeks to highlight a contemporary approach to the diagnosis of food allergy in children strategies.

Severe Anaphylaxis to Volplex, a Colloid Solution during Cesarean Section: A Case Report and Review

Anaphylaxis is a life-threatening event that can occur anytime during pregnancy. It has been reported following administration of various substances with adverse maternal and neonatal consequences. It should be considered in the differential diagnosis of intrapartum collapse. We encountered a case of severe anaphylactic reaction following a routine cesarean section. It is very important that all members of the perinatal team are aware of early recognition and management of anaphylactic reaction. We think that it is important to highlight this as a further case report of severe anaphylactic reaction to a colloid solution and discuss the pathophysiology and management.

Concurrent blockade of platelet-activating factor and histamine prevents life-threatening peanut-induced anaphylactic reactions

BACKGROUND

Food anaphylaxis is an acute and life-threatening systemic allergic reaction. Fatality registries place peanut as the most common culprit of fatal and near-fatal reactions in North America. Because prophylaxis and treatment have advanced little in recent years, it is imperative to evaluate novel therapies.

OBJECTIVE

To investigate the impact of blocking mast cell mediators in a mouse model of peanut-induced anaphylaxis.

METHODS

Mice were sensitized with peanut protein and cholera toxin via oral gavage weekly for 4 weeks. One week after the last sensitization, separate groups of mice were treated with either a (1) 5-lypoxygenase inhibitor, (2) a platelet-activating factor (PAF) receptor antagonist, (3) histamine receptor antagonists, or (4) a PAF receptor antagonist along with histamine receptor antagonists before peanut challenge.

RESULTS

Treatment targeting either leukotrienes or histamine alone had no beneficial effects. In contrast, PAF antagonism significantly attenuated the magnitude and duration of the anaphylactic reactions. Particularly, it prevented severe reactions. Moreover, 83% of PAF-treated versus 43% of untreated mice reached recovery within 120 minutes after peanut challenge. Notably, combined blockade of PAF and histamine had a clearly greater beneficial effect. In fact, all but 1 mouse developed mild, if any, anaphylactic reactions. In addition, combination therapy was associated with a significant decrease in vascular leakage and release of vasoactive mediators after peanut challenge.

CONCLUSION

Combination therapy blocking both PAF and histamine markedly reduces the severity of peanut-induced anaphylaxis, and thus it may be a potential life-saving therapeutic approach in peanut and, likely, other food-induced anaphylaxis.

Two Case Reports of Life-Threatening Ethanol-Induced Anaphylaxis

Adverse reactions to alcoholic beverages are common and diverse in aetiology. Ethanol-induced anaphylaxis, however, is a rare but often life-threatening condition that warrants careful evaluation in suspected individuals. We present the cases of two patients who developed urticaria, angioedema and throat constriction within minutes of consuming white wine. Both individuals demonstrated no adverse reaction to double-blind placebo-controlled challenges to metabisulphite or sodium salicylate. However, an open challenge to white wine elicited urticaria in both subjects. This reaction was reproduced with a double-blind placebo-controlled challenge to ethanol and was accompanied by a rise in serum total tryptase levels. Positive skin test responses to 2% acetic acid, a breakdown product of ethanol, were elicited from both patients but not from three normal controls. These two cases demonstrate the need for a systematic approach for the evaluation of allergic reactions to alcohol.