A Quantitative Method for Detecting Ara h 2 by Generation and Utilization of Monoclonal Antibodies.
Peanut (Arachis hypogaea) is one of the most common food allergens that can induce fatal anaphylaxis, and Ara h 2 is one of the major allergen components involved in peanut allergy. The aim of this study was to develop a quantitative method for detecting peanut allergen using monoclonal antibodies against Ara h 2. The splenocytes of immunized mice were fused with myeloma cells (SP2/0), and stable mAb-producing clones were obtained by limiting dilution. mAbs against Ara h 2 were isolated from mouse ascites, and specificity was confirmed by immunoblotting. Five mAbs with high purity and specific reactivity were obtained, which were referred to as 1-2E10, 2-1D5, 3-1C5, 4-1C2, and 5-1G4, respectively. After screening different mAb combinations for development of a sandwich ELISA, we selected 5-1G4 as the capture antibody and 1-2E10 as the detection antibody for the measurement of Ara h 2 from which an optimal correlation between the Ara h 2 concentration and the OD value was obtained. This sandwich ELISA could specifically detect Ara h 2 in peanut extract at concentrations as low as 5 ng/mL and up to 10 μg/mL. These mAbs can, therefore, serve as quantitative diagnostic reagents for peanut and peanut product risk assessment.
Pine nut allergy in Korean children: Clinical characteristics and diagnostic values of specific IgE against pine nuts.
BACKGROUND: Hypersensitivity reactions to pine nuts in children have been occasionally encountered recently, although reports on pine nut allergy cases are rare worldwide. The study aimed to feature clinical and laboratory findings pertaining to pine nut allergy in Korean children. METHODS: Forty-two subjects were enrolled through a retrospective review of medical records, from September 2010 to December 2015, at the Department of Pediatrics in Ajou University Hospital. The demographic profiles, clinical characteristics, and laboratory findings were evaluated. RESULTS: Twenty-four patients showed immediate-type reactions after exposure to pine nuts (the allergic group), while the remaining 18 were atopic controls, who exhibited no allergic symptoms (the tolerant group). The median age of the subjects in the allergic group was three years. More than half of the subjects in this group experienced allergic symptoms within 5min, and seven of them experienced anaphylaxis. The median level of pine nut-specific immunoglobulin E (sIgE) in the allergic group (1.62kUA/L) was significantly higher (p=0.014) than that in the tolerant group (0.11kUA/L), with an optimal cut-off level of 0.40kUA/L (sensitivity, 66.7% and specificity, 77.8%). The positive decision point of pine nut-sIgE (specificity, 100%) to distinguish the allergic and tolerant groups was 2.84kUA/L. However, there was no difference in pine nut-sIgE levels between the anaphylaxis and non-anaphylaxis cases. CONCLUSION: About 30% of children with pine nut allergy experienced anaphylaxis. The optimal cut-off level of pine nut-sIgE to distinguish the allergic and tolerant groups was 0.40kUA/L and the positive decision point was 2.84kUA/L.
Role of dendritic cells in peanut allergy.
The prevalence of peanut allergy (PA) has increased, affecting approximately 1.1% of children in Western countries. PA causes life-threatening anaphylaxis and frequently persists for life. There are no standardized curative therapies for PA, and avoidance of peanuts remains the main therapeutic option. A better understanding of the pathogenesis of PA is essential to identify new treatment strategies. Intestinal dendritic cells (DCs) are essential in the induction and maintenance of food tolerance because they present dietary allergens to T cells, thereby directing subsequent immune responses. Areas covered: In this review, we discuss the factors related to the acquisition of oral tolerance to peanut proteins. We focus on intestinal DC-related aspects, including the latest advances in the biology of intestinal DC subtypes, effect of tolerance-inducing factors on DCs, effect of dietary components on oral tolerance, and role of DCs in peanut sensitization. Expert commentary: Given the increasing prevalence of PA, difficulty of avoiding peanut products, and the potentially serious accidental reactions, the development of novel therapies for PA is needed. The ability of DCs to trigger tolerance or immunity makes them an interesting target for new treatment strategies against PA.
Threshold dose distribution for cashew nut allergy in children.
Allergy to cashew nut in children is increasingly recognized in clinical practice and the prevalence of this allergy seems to increase. Furthermore, previous studies showed the potential for cashew nut to cause anaphylaxis [1]. Despite the increasing prevalence of cashew nut allergy and the severity of the reaction to this allergen, there are only few studies on this allergy, especially on the threshold dose.
Peanut allergens.
Peanut allergens have the potential to negatively impact on the health and quality of life of millions of consumers worldwide. The seeds of the peanut plant Arachis hypogaea contain an array of allergens that are able to induce the production of specific IgE antibodies in predisposed individuals. A lot of effort has been focused on obtaining the sequences and structures of these allergens due to the high health risk they represent. At present, 16 proteins present in peanuts are officially recognized as allergens. Research has also focused on their in-depth immunological characterization as well as on the design of modified hypoallergenic derivatives for potential use in clinical studies and the formulation of strategies for immunotherapy. Detailed research protocols are available for the purification of natural allergens as well as their recombinant production in bacterial, yeast, insect, and algal cells. Purified allergen molecules are now routinely used in diagnostic multiplex protein arrays for the detection of the presence of allergen-specific IgE. This review gives an overview on the wealth of knowledge that is available on individual peanut allergens.
Tree nut allergens
Tree nuts are considered as part of a healthy diet due to their high nutritional quality. However, they are also a potent source of allergenic proteins inducing IgE mediated hypersensitivity often causing serious, life-threatening reactions. The reported prevalence of tree nut allergy is up to 4.9% worldwide. The general term "tree nuts" comprises a number of nuts, seeds, and drupes, derived from trees from different botanical families. For hazelnut and walnut several allergens have been identified which are already partly applied in component resolved diagnosis, while for other tree nuts such as macadamia, coconut, and Brazil nut only individual allergens were identified and data on additional allergenic proteins are missing. This review summarizes the current knowledge on tree nut allergens and describes their physicochemical and immunological characterization and clinical relevance.
Tree Nut Allergies: Allergen Homology, Cross-reactivity, and Implications for Therapy.
Tree nut allergy is a potentially life-threatening disease that is increasing in prevalence, now affecting 1% of the general population in the United States. While other food allergies often resolve spontaneously, tree nut allergies are outgrown in less than 10% of cases. Due to the likelihood of cross-sensitization to multiple tree nut allergens, the current treatment guideline is strict avoidance of all nuts once one tree nut allergy has been diagnosed. For example, walnut and pecan are highly cross-reactive, along with cashew and pistachio, but the extent of clinical, IgE-mediated cross-reactivity among other tree nuts remains unclear, therefore making avoidance of all tree nuts a safe approach. There have been recent advances in immunotherapy for food allergies. For instance, there are investigational immunotherapies for milk, egg, and peanut allergies, specifically oral immunotherapy (OIT), sublingual immunotherapy (SLIT) and epicutaneous immunotherapy (EPIT). However, there are no large randomized controlled clinical trials for tree nut allergies. Even though there has been less research into tree nut allergy immunotherapies, the evidence of T cell cross-reactivity among tree nuts exists in animal models and in T cells from allergic patients indicates that immunotherapeutic interventions may be possible. Here, we review literature regarding epidemiology, allergen homology, and cross-reactivity among tree nuts, and explore how current findings can be employed for effective therapy.
Advances in the Approach to the Patient with Food Allergy.
Advances in food allergy diagnosis, management, prevention and therapeutic interventions have been significant over the past two decades. Evidence based national and international guidelines have streamlined food allergy diagnosis and management, while paradigm shifting work in primary prevention of peanut allergy has resulted in significant modifications in the approach to early food introduction in infants and toddlers. Innovative investigation of food allergy epidemiology, systems biology, impact, and management has provided important insights. While active therapeutic approaches to food allergy presently remain experimental, progress toward licensed therapies has been substantial. Mechanistic understanding of the immunologic processes underlying food allergy and immunotherapy will inform the future design of therapeutic approaches targeting the food allergic response. Global strategies to mitigate the substantial medical, economic, and psychosocial burden of food allergy in affected individuals and families will require engagement of stakeholders across multiple sectors in research, healthcare, public health, government, educational institutions and industry. However, the relationship between the well-informed allergy care provider and the patient and family remains fundamental for optimizing the care of the patient with food allergy.
The effect of oral immunotherapy treatment in severe IgE mediated milk, peanut, and egg allergy in adults.
INTRODUCTION: The standard care of severe food allergy in both adults and children means avoidance of allergens. In recent years promising results of oral immunotherapy (OIT) have been reported in children. In adults, information on OIT in severe food allergy is very limited. OBJECTIVE: We aimed to study if OIT is possible in adults. METHODS: We report OIT results in 10 adult patients with milk OIT, nine adult patients with peanut OIT, and four adult patients with egg OIT. The allergy was confirmed with allergen specific IgE tests and oral food challenges (open in milk allergy and double-blind in peanut and egg allergy). The OIT was performed as open. RESULTS: The median dose of protein that led to discontinuation of allergen challenge because of symptoms was 7.5 mg in milk allergy, 25 mg in peanut allergy, and 15 mg in egg allergy. The median period of OIT was 515 days. Currently on OIT are 6/10 milk allergic patients, 4/9 peanut allergic patients and 3/4 egg allergic patients. The median dose of milk protein increased by 60-fold during OIT compared to the allergen challenge dose. In peanut OIT the median dose increased by eightfold and in egg allergy the dose increased with OIT by 35-fold. Local itching was the most common side effect of OIT (73.9% of the patients), four patients reported having used epinephrine autoinjector and three patients having needed emergency room treatment. CONCLUSIONS AND CLINICAL RELEVANCE: OIT can be given in adult patients with severe milk, peanut, or egg allergy only in selected cases. OIT leads into desensitization but it is not clear whether persistent tolerance can be achieved. Mild adverse events during OIT are common.
Preventing Peanut Allergy.
The rising prevalence of food allergy and specifically peanut allergy has had significant implications for affected patients, families, and society. The current standard of care remains strict avoidance and the use of emergency medications for accidental ingestions. There is recent evidence-based information to suggest that one approach to preventing peanut allergy lies in early introduction of peanut. This represents a paradigm shift from previous recommendations and has led to updated guidelines in the United States, Europe, and Australasia on the introduction of potentially allergenic foods in the infant diet. This new approach to prevention has some practical obstacles and challenges associated with its implementation. There is also growing interest in the role of maintaining a healthy skin barrier in prevention of sensitization and food allergy. Other approaches, including pro- and prebiotics, prenatal maternal dietary avoidance, breastfeeding, and the use of specific formulas, have not shown reproducibly favorable results. As children with peanut allergy are unlikely to outgrow their food allergy, early oral immunotherapy in those with established peanut allergy is being investigated with the hopes of altering the natural history of an otherwise lifelong disease.