Performance of basophil activation test and specific IgG4 as diagnostic tools in nonspecific lipid transfer protein allergy: Antwerp-Barcelona comparison

Evaluation and Updated Classification of Acute Hypersensitivity Reactions to Nonsteroidal Anti-Inflammatory Drugs (NSAIDs): NSAID-Exacerbated or -Induced Food Allergy

BACKGROUND

There are hypersensitivity reactions (HRs) to foods in which nonsteroidal anti-inflammatory drugs (NSAIDs) act as aggravating factors (NSAID-exacerbated food allergy [NEFA]) or cofactors (NSAID-induced food allergy [NIFA]), often misdiagnosed as HRs to NSAIDs. Urticarial/angioedematous and/or anaphylactic reactions to two or more chemically unrelated NSAIDs do not meet current classification criteria. However, they may be considered part of a cross-reactive type of acute HR, which is NSAID-induced urticaria/angioedema with or without respiratory or systemic symptoms of anaphylaxis.

OBJECTIVE

To evaluate patients reporting acute HRs to NSAIDs and classify them according to updated criteria.

METHODS

We prospectively studied 414 patients with suspected HRs to NSAIDs. For all whom met these criteria, NEFA/NIFA was diagnosed: (1) mild reactions to (NEFA) or tolerance of (NIFA) the suspected foods without taking NSAIDs; (2) cutaneous and/or anaphylactic reactions to the combination foods plus NSAIDs; (3) positive allergy tests to the suspected foods; and (4) negative drug challenges (DCs) with the NSAIDs involved.

RESULTS

A total of 252 patients were given the diagnosis of NSAID hypersensitivity (60.9%), 108 of whom had NSAID-induced urticaria/angioedema with or without respiratory or systemic symptoms of anaphylaxis. We excluded NSAID hypersensitivity in 162 patients (39.1%) who tolerated DCs with the suspected NSAIDs, nine of whom received a diagnosis of NEFA, and 66 of NIFA. Pru p 3 was implicated in 67 of those 75 patients who received a diagnosis of NEFA or NIFA.

CONCLUSIONS

NEFA and NIFA account for about 18% of patients reporting HRs to NSAIDs, in which Pru p 3 is the main responsible food allergen. Therefore, patients with cutaneous and/or anaphylactic reactions to NSAIDs should be carefully questioned about all foods ingested within 4 hours before or after NSAID exposure, and targeted food allergy tests should be considered in the diagnostic workup of these patients. If testing is positive, DCs with the suspected NSAIDs should also be considered.

EAACI Molecular Allergology User's Guide 2.0

Since the discovery of immunoglobulin E (IgE) as a mediator of allergic diseases in 1967, our knowledge about the immunological mechanisms of IgE-mediated allergies has remarkably increased. In addition to understanding the immune response and clinical symptoms, allergy diagnosis and management depend strongly on the precise identification of the elicitors of the IgE-mediated allergic reaction. In the past four decades, innovations in bioscience and technology have facilitated the identification and production of well-defined, highly pure molecules for component-resolved diagnosis (CRD), allowing a personalized diagnosis and management of the allergic disease for individual patients. The first edition of the "EAACI Molecular Allergology User's Guide" (MAUG) in 2016 rapidly became a key reference for clinicians, scientists, and interested readers with a background in allergology, immunology, biology, and medicine. Nevertheless, the field of molecular allergology is moving fast, and after 6 years, a new EAACI Taskforce was established to provide an updated document. The Molecular Allergology User's Guide 2.0 summarizes state-of-the-art information on allergen molecules, their clinical relevance, and their application in diagnostic algorithms for clinical practice. It is designed for both, clinicians and scientists, guiding health care professionals through the overwhelming list of different allergen molecules available for testing. Further, it provides diagnostic algorithms on the clinical relevance of allergenic molecules and gives an overview of their biology, the basic mechanisms of test formats, and the application of tests to measure allergen exposure.

Anaphylaxis across Europe: are pollen food syndrome and lipid transfer protein allergy so far apart?

PURPOSE OF REVIEW

Traditionally pollen-food syndrome (PFS) is considered to be a mild cross-reacting food allergy affecting only Northern Europe, with lipid transfer protein (LTP) allergy being more severe and mainly occurring in Southern Europe. This review seeks to update the reader on both types of plant food allergy and to determine whether the stereotypical presentations of these plant food allergies remain the same, with a particular focus on reaction severity.

RECENT FINDINGS

Recent findings suggest that both these types of plant food allergy occur in children and adults. Although it is true that PFS allergy is more prevalent in Northern Europe and LTP allergy is more well known in Southern Europe, these conditions are not hidebound by geography, and the increasing spread and allergenicity of pollen due to global warming continues to change their presentation. Both conditions have a spectrum of symptom severity, with PFS sometimes presenting with more severe symptoms, including anaphylaxis and LTP allergy with milder reactions.

SUMMARY

It is important to consider that in many parts of Europe, reactions to plant foods, especially fruits or vegetables, could be mediated either by pollen cross-reactivity or primary sensitization to LTP allergens. All those presenting with symptoms to plant foods will benefit from a detailed clinical history and appropriate tests so that an accurate diagnosis can be made, and correct management implemented.

Low Levels Matter: Clinical Relevance of Low Pru p 3 sIgE in Patients With Peach Allergy

Many clinical lab settings still use 0.35 KUA/L as the cut-off for serum specific-IgE (sIgE) immunoassays, while the detection limit is 0.1 KUA/L. The clinical relevance of -low-level sIgE (0.1–0.35 KUA/L) remains controversial. Pru p 3 sIgE is considered to be the main routine tool for assessing lipid transfer protein (LTP) sensitization. We aimed to evaluate the clinical relevance of Pru p 3 sIgE low levels in a population diagnosed with LTP allergy. Adults diagnosed with LTP allergy and Pru p 3 sIgE ≥ 0.1 KUA/L between 2012 and 2019 were included. Clinical data were reviewed. nPru p 3 basophil activation test (BAT) was performed and basophil reactivity (BR) and sensitivity (BS) correlated with the peach allergy symptoms. Pru p 3 sIgE from 496 subjects was recorded, 114 (23.0%) between 0.1 and 0.34 KUA/L (grLOW), the rest ≥ 0.35 KUA/L (grB). A total of 44.7% in grLOW and 59.9% in grB were allergic. Urticaria was more frequent in grLOW. In grLOW, Pru p 3 sIgE was higher in patients with local compared with systemic symptoms. In grB, Pru p 3 sIgE was higher in allergic patients. Pru p 3/Total IgE ratios were higher in allergic vs. tolerant in both groups. In BAT, BR was similar in both groups. In grLOW, it was higher on allergic compared with tolerant (p = 0.0286), and on those having systemic vs. local symptoms (p = 0.0286). BS showed no significant difference between groups. Patients with low levels represent a non-negligible fraction and around 45% are peach allergic. BAT showed functional sIgE in them. Pru p 3 sensitizations should be carefully evaluated even when sIgE levels are low.

Rosaceae food allergy: a review

This review provides a global overview on Rosaceae allergy and details the particularities of each fruit allergy induced by ten Rosaceae species: almond/peach/cherry/apricot/plum (Amygdaleae), apple/pear (Maleae), and raspberry/blackberry/strawberry (Rosoideae). Data on clinical symptoms, prevalence, diagnosis, and immunotherapies for the treatment of Rosaceae allergy are herein stated. Allergen molecular characterization, cross-reactivity/co-sensitization phenomena, the impact of food processing and digestibility, and the methods currently available for the Rosaceae detection/quantification in foods are also described. Rosaceae allergy has a major impact in context to pollen-food allergy syndrome (PFAS) and lipid transfer protein (LTP) allergies, being greatly influenced by geography, environment, and presence of cofactors. Peach, apple, and almond allergies are probably the ones most affecting the quality of life of the allergic-patients, although allergies to other Rosaceae fruits cannot be overlooked. From patients' perspective, self-allergy management and an efficient avoidance of multiple fruits are often difficult to achieve, which might raise the risk for cross-reactivity and co-sensitization phenomena and increase the severity of the induced allergic responses with time. At this point, the absence of effective allergy diagnosis (lack of specific molecular markers) and studies advancing potential immunotherapies are some gaps that certainly will prompt the progress on novel strategies to manage Rosaceae food allergies.

The diagnosis and management of allergic reactions in patients sensitized to non-specific lipid transfer proteins

Sensitization to one or more non-specific lipid transfer proteins (nsLTPs), initially thought to exist mainly in southern Europe, is becoming accepted as a cause of allergic reactions to plant foods across Europe and beyond. The peach nsLTP allergen Pru p 3 is a dominant sensitizing allergen and peaches a common food trigger, although multiple foods can be involved. A frequent feature of reactions is the requirement for a cofactor (exercise, alcohol, non-steroidal anti-inflammatory drugs, Cannabis sativa) to be present for a food to elicit a reaction. The variability in the food and cofactor triggers makes it essential to include an allergy-focused diet and clinical history in the diagnostic workup. Testing on suspected food triggers should also establish whether sensitization to nsLTP is present, using purified or recombinant nsLTP allergens such as Pru p 3. The avoidance of known trigger foods and advice on cofactors is currently the main management for this condition. Studies on immunotherapy are promising, but it is unknown whether such treatments will be useful in populations where Pru p 3 is not the primary sensitizing allergen. Future research should focus on the mechanisms of cofactors, improving diagnostic accuracy and establishing the efficacy of immunotherapy.

The Role of Lipid Transfer Proteins as Food and Pollen Allergens Outside the Mediterranean Area

PURPOSE OF REVIEW

To provide an overview of the prevalence and clinical manifestation of non-specific lipid transfer proteins (LTP)-mediated allergies outside the Mediterranean area and to address potential reasons for the different geographical significance of LTP-driven allergies.

RECENT FINDINGS

LTPs are major allergens in the Mediterranean area, which frequently can elicit severe reactions. Pru p 3 the LTP from peach is reported as genuine allergen and is considered a prototypic marker for LTP-mediated allergies. However, both food and pollen LTP allergies exist outside the Mediterranean area, but with lower clinical significance, different immunogenicity, and less clarified role. Evidence has been reported that in areas with high exposure to pollen, in particular to mugwort, pollen-derived LTPs can act as a primary sensitizer to trigger secondary food allergies. Co-sensitization to unrelated allergens might be causative for less severe reactions in response to LTPs. However, the reason for the geographical different sensitization patterns to LTPs remains unclear.

Are Physicochemical Properties Shaping the Allergenic Potency of Plant Allergens?

This review searched for published evidence that could explain how different physicochemical properties impact on the allergenicity of food proteins and if their effects would follow specific patterns among distinct protein families. Owing to the amount and complexity of the collected information, this literature overview was divided in two articles, the current one dedicated to protein families of plant allergens and a second one focused on animal allergens. Our extensive analysis of the available literature revealed that physicochemical characteristics had consistent effects on protein allergenicity for allergens belonging to the same protein family. For example, protein aggregation contributes to increased allergenicity of 2S albumins, while for legumins and cereal prolamins, the same phenomenon leads to a reduction. Molecular stability, related to structural resistance to heat and proteolysis, was identified as the most common feature promoting plant protein allergenicity, although it fails to explain the potency of some unstable allergens (e.g. pollen-related food allergens). Furthermore, data on physicochemical characteristics translating into clinical effects are limited, mainly because most studies are focused on in vitro IgE binding. Clinical data assessing how these parameters affect the development and clinical manifestation of allergies is minimal, with only few reports evaluating the sensitising capacity of modified proteins (addressing different physicochemical properties) in murine allergy models. In vivo testing of modified pure proteins by SPT or DBPCFC is scarce. At this stage, a systematic approach to link the physicochemical properties with clinical plant allergenicity in real-life scenarios is still missing.

Type 2 immunity in the skin and lungs

There has been extensive progress in understanding the cellular and molecular mechanisms of inflammation and immune regulation in allergic diseases of the skin and lungs during the last few years. Asthma and atopic dermatitis (AD) are typical diseases of type 2 immune responses. interleukin (IL)-25, IL-33, and thymic stromal lymphopoietin are essential cytokines of epithelial cells that are activated by allergens, pollutants, viruses, bacteria, and toxins that derive type 2 responses. Th2 cells and innate lymphoid cells (ILC) produce and secrete type 2 cytokines such as IL-4, IL-5, IL-9, and IL-13. IL-4 and IL-13 activate B cells to class-switch to IgE and also play a role in T-cell and eosinophil migration to allergic inflammatory tissues. IL-13 contributes to maturation, activation, nitric oxide production and differentiation of epithelia, production of mucus as well as smooth muscle contraction, and extracellular matrix generation. IL-4 and IL-13 open tight junction barrier and cause barrier leakiness in the skin and lungs. IL-5 acts on activation, recruitment, and survival of eosinophils. IL-9 contributes to general allergic phenotype by enhancing all of the aspects, such as IgE and eosinophilia. Type 2 ILC contribute to inflammation in AD and asthma by enhancing the activity of Th2 cells, eosinophils, and their cytokines. Currently, five biologics are licensed to suppress type 2 inflammation via IgE, IL-5 and its receptor, and IL-4 receptor alpha. Some patients with severe atopic disease have little evidence of type 2 hyperactivity and do not respond to biologics which target this pathway. Studies in responder and nonresponder patients demonstrate the complexity of these diseases. In addition, primary immune deficiency diseases related to T-cell maturation, regulatory T-cell development, and T-cell signaling, such as Omenn syndrome, severe combined immune deficiencies, immunodysregulation, polyendocrinopathy, enteropathy, X-linked syndrome, and DOCK8, STAT3, and CARD11 deficiencies, help in our understanding of the importance and redundancy of various type 2 immune components. The present review aims to highlight recent advances in type 2 immunity and discuss the cellular sources, targets, and roles of type 2 mechanisms in asthma and AD.