Comparing the risk of anaphylaxis requiring epinephrine in oral immunotherapy and subcutaneous immunotherapy: A review of recent Canadian real-world literature

Background

The safety of pediatric food oral immunotherapy (Ped-OIT) has been depicted by some as less favorable than subcutaneous immunotherapy (SCIT) owing to the increased number of serious adverse events requiring epinephrine. A review of real-world data comparing Ped-OIT and SCIT safety is necessary to guide shared decision making.

Objectives

Our aim was to compare the safety and adverse event profiles of peanut Ped-OIT and SCIT using Canadian real-word literature.

Methods

We performed a retrospective review of recent Canadian real-world literature on peanut Ped-OIT and SCIT safety and adverse events.

Results

The incidences of systemic reactions requiring epinephrine were 11 in 270 patients (4.07%) and 12 in 41,020 doses (0.029%) in a multicenter study in British Columbia, Alberta, Manitoba, and Nova Scotia studying 270 preschool-age children treated with peanut OIT. Similarly, a multicenter study in South-Western Ontario examining 160 patients between the ages of 1 and 17 years who were treated with peanut OIT showed that the incidences of systemic reactions requiring epinephrine were 5 in 160 patients (3.1%) and 8 in 52,751 doses (0.015%). A single-center retrospective review of 380 patients receiving aeroallergen SCIT showed that the incidences of systemic reactions requiring epinephrine were 28 in 380 patients (7.4%) and 1 in 1047 injection visits (0.095%). These findings are comparable to those of a review of 860 patients in Ontario who received either aeroallergen or venom SCIT, in which the incidence of systemic reaction requiring epinephrine was 10 in 4242 injections (0.24%).

Conclusion

Despite differences in the OIT protocols used and age groups studied, recent real-world data suggest that the safety of preschool peanut OIT or peanut OIT using a slower buildup schedule is comparable to that of SCIT.

Food protein-induced enterocolitis syndrome in an infant triggered by prunes

BACKGROUND

Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE mediated food allergy that has a cumulative incidence of 0.015 to 0.7% in infants [1]. The most common allergens causing FPIES reactions include cow's milk, followed by soy, grains, and rice [1, 3]. Increasing clinical awareness of FPIES has resulted in the expansion of emerging triggers of FPIES, including fruit antigens.

CASE PRESENTATION

We describe an infant diagnosed with FPIES to prune.

CONCLUSION

Fruit allergens are an emerging group of triggers for FPIES, both in their fresh and dried forms. To our knowledge, this case is the first presentation of FPIES to prunes (dehydrated plum). This case highlights that careful history taking can avoid unnecessary investigations and delay in diagnosing FPIES.

A148 CASE REPORT: ASSOCIATION OF HOUSE DUST MITE ALLERGY AND REMISSION OF EOSINOPHILIC ESOPHAGITIS AFTER ELIMINATION OF SHRIMP

Background

Eosinophilic esophagitis (EoE) is a complex, chronic, allergic disease that commonly presents as dysphagia in young adults. Co-occurring allergic or atopic disease, including food allergies and asthma are seen in approximately 70% of cases. Allergy to house dust mite (HDM) tropomyosin, Der p 10, and cross-reactivity to shrimp has been well described. We discuss a presentation of EoE in the setting of positive HDM skin prick testing that subsequently improved with dietary elimination of shrimp, that has never been described in the literature.

Purpose

To highlight an underlying mechanism in EoE and the importance of a multidisciplinary approach to this disease.

Method

A 45-year-old male with a medical history significant for ulcerative colitis (diagnosed two years prior and maintained in deep endoscopic remission with adalimumab) and asthma (with seasonal, rare usage of budesonide and formoterol inhaler) was seen by his outpatient gastroenterologist following three weeks of new-onset dysphagia and subjective intermittent food bolus impaction. The patient was pre-emptively started on daily proton pump inhibitor prior to endoscopy, but discontinued this within less than two weeks as he felt like it induced loose bowel movements. Esophagogastroduodenoscopy (EGD) was performed and revealed proximal esophageal furrows. Histology of esophageal biopsies was compatible with EoE: distal esophagus >100 eosinophils/hpf with eosinophil degranulation, mid and proximal esophagus >25 eosinophils/hpf with eosinophil degranulation. The patient self-identified that his episodes of dysphagia and food bolus impaction were associated with shrimp ingestion, thus he eliminated shrimp from his diet.

Result(s)

Two-month clinical follow-up demonstrated symptomatic remission despite no other active treatment or additional food elimination. Consultation with an allergist demonstrated the patient had positive skin prick testing to HDM (Dermatophagoides pteronyssinus and farina) but negative testing to shrimp, despite clinical improvement with dietary shrimp elimination. Thus his EoE was attributed to HDM cross-reactivity, specifically to the Der p 10 antigen. Follow-up EGD and biopsy to confirm endoscopic and histologic remission with shrimp elimination is scheduled in two months.

Conclusion(s)

This is the first case description of a patient with new onset EoE attributed to Der p 10, in the setting of positive skin prick to HDM and negative skin prick to shrimp, with subsequent symptomatic resolution of EoE following dietary shrimp elimination. Shrimp and HDM share a protein, Der p 10. Der p 10 is commonly the culprit antigen in patients that have allergic reactions to HDM and (or) shrimp, but often only demonstrate positive skin prick testing to HDM (with negative testing to shrimp). This case demonstrates a role for involvement of an allergist and skin prick testing in select cases of EoE, as this may result in a relatively simple food elimination and avoidance of further therapeutic interventions.

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Disclosure of Interest

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Effectiveness of C1-INH therapy in angiotensin converting enzyme inhibitor induced angioedema

Introduction

Angiotensin Converting Enzyme Inhibitors (ACEI) are a common cause of Emergency Room presentation for angioedema. Although no treatment guidelines exist, C1 esterase inhibitor concentrate (C1-INH) is used on an off label basis for management of ACEI acquired angioedema (ACEI AAE).

Objective

To evaluate the efficacy of C1-INH in management of ACEI AAE at our local centers.

Results

Nine patients, from 3 academic sites, were identified through Allergy Service consultation data and records from Diagnostic Services Manitoba, Canada from 2010–2020. The majority of the patients (n = 8/9) required endotracheal intubation prior to the initiation of C1-INH. Overall, approximately 56% of patients (n = 5/9) had resolution of angioedema ranging between 12 and 17 h, with a median time of 13.5 h, and no recurrence after the administration of C1-INH concentrate. One patient had transient symptom resolution in 14 h, however, recurrence of angioedema required re-intubation. The remainder of patients (n = 4/9), had resolution of angioedema between 22 and 72 h, with a median time of 33.75 h.

Conclusion

Our findings demonstrate continued ambivalence of the efficacy and role of C1-INH concentrate in the treatment of ACEI AAE, secondary to multiple uncontrolled confounding factors. Further research into characterizing a subgroup of intubated patients in our study that responded to C1-INH concentrate needs to be completed.

Functional characterization of an N-terminally-truncated mitochondrial porin expressed in Neurospora crassa

Mitochondrial porin, which forms voltage-dependent anion-selective channels (VDAC) in the outer membrane, can be folded into a 19-β-stranded barrel. The N terminus of the protein is external to the barrel and contains α-helical structure. Targeted modifications of the N-terminal region have been assessed in artificial membranes, leading to different models for gating in vitro. However, the in vivo requirements for gating and the N-terminal segment of porin are less well-understood. Using Neurospora crassa porin as a model, the effects of a partial deletion of the N-terminal segment were investigated. The protein, ΔN2-12porin, is assembled into the outer membrane, albeit at lower levels than the wild-type protein. The resulting strain displays electron transport chain deficiencies, concomitant expression of alternative oxidase, and decreased growth rates. Nonetheless, its mitochondrial genome does not contain any significant mutations. Most of the genes that are expressed in high levels in porin-less N. crassa are expressed at levels similar to that of wild type or are slightly increased in ΔN2-12porin strains. Thus, although the N-terminal segment of VDAC is required for complete function in vivo, low levels of a protein lacking part of the N terminus are able to rescue some of the defects associated with the absence of porin.