Consideration for alpha-gal syndrome in two critically ill persons with group O blood who received group B plasma.

BACKGROUND: The U.S. Centers for Disease Control and Prevention (CDC) has reported increasing rates of alpha-gal syndrome, an allergic response after meat ingestion (AGS). AGS has been associated with prior exposure to tick bites or other biologics characterized by a life-threatening immunoglobulin E (IgE)-mediated hypersensitivity to galactose-alpha-1,3-galactose (alpha-gal) an oligosaccharide structurally similar to the group B antigen on red blood cells (RBC) found in most non-primate mammalian meat and products derived from these mammals. In 2023, Transfusion reported 3 group O recipients of group B plasma in the Washington, D.C. metropolitan area with no history of meat allergy who had anaphylactic transfusion reactions compatible with AGS. AIMS: We investigated allergic reactions in 2 additional patients who received ABO minor-incompatible blood products at 2 hospitals in the D.C. area during fall 2023. METHODS: For both patients, a medical chart review was performed and IgE levels to alpha-gal were measured. RESULTS: The first patient, a 64-year-old, O-positive patient status post heart transplant with no known allergies, was admitted with acute COVID-19 induced antibody-mediated transplant rejection and placed on extracorporeal membrane oxygenation (ECMO). While undergoing plasma exchange (PLEX) (50% albumin/50% fresh frozen plasma (FFP)), the patient tolerated 2 units of group O FFP and 1 unit of group A FFP before becoming hemodynamically unstable during transfusion of 1 unit of B-positive FFP. PLEX was stopped. The patient later died of sepsis from underlying causes. The second patient, a 57-year-old O-positive man with a history of melanoma and neuro fibromatosis type 1, was undergoing an abdominal resection including transfusion of 3 units of O-positive RBC when he suffered hypotension and ventricular tachycardia requiring intraoperative code after receiving 2 units of group B FFP. Hiveswere noted after resuscitation. The patient had a history of tick bites but no known allergies. He is alive 5 months after the possible allergic event. Both patients had full transfusion reaction evaluations and immunology testing results above the positive cutoff for anti-alpha-gal IgE. DISCUSSION AND CONCLUSION: Two patients with O-positive blood and no known allergies experience danaphyl axis after transfusion with group B FFP. The symptoms cannot definitively be imputed to an allergic transfusion reaction, but the presence of IgE against alpha-gal supports an association. Medicating patients with antihistamines and IV steroids pre-transfusion may prevent allergic reactions. Restricting group B plasma-containing products (plasma, platelets, cryoprecipitate) for patients who experience AGS-like symptoms may be considered.

Serological profiling reveals hsa-miR-451a as a possible biomarker of anaphylaxis.

BackgroundThere is a need to support the diagnosis of anaphylaxis by objective markers. miRNAs are promising noncoding RNA species that may serve as serological biomarkers, but their use in diagnosing anaphylaxis has not been systematically studied to our knowledge. We aimed to comprehensively investigate serum biomarker profiles (proteins, lipids, and miRNAs) to support the diagnosis of anaphylaxis.MethodsAdult patients admitted to the emergency room with a diagnosis of anaphylaxis (<3 hours) were included. Blood samples were taken upon emergency room arrival and 1 month later.ResultsNext-generation sequencing of 18 samples (6 patients with anaphylaxis in both acute and nonacute condition, for 12 total samples, and 6 healthy controls) identified hsa-miR-451a to be elevated during anaphylaxis, which was verified by quantitative real-time PCR in the remaining cohort. The random forest classifier enabled us to classify anaphylaxis with high accuracy using a composite model. We identified tryptase, 9α,11ß-PGF2, apolipoprotein A1, and hsa-miR-451a as serological biomarkers of anaphylaxis. These predictors qualified as serological biomarkers individually but performed better in combination.ConclusionUnexpectedly, hsa-miR-451a was identified as the most relevant biomarker in our data set. We were also able to distinguish between patients with a history of anaphylaxis and healthy individuals with higher accuracy than any other available model. Future studies will need to verify miRNA biomarker utility in real-life clinical settings.FundingThis work is funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) as part of the clinical research unit (CRU339): Food Allergy and Tolerance (FOOD@) (project number 409525714) and a grant to MW (Wo541-16-2, project number 264921598), as well as by FOOD@ project numbers 428094283 and 428447634.

Anaphylaxis: Mediators, Biomarkers, and Microenvironments

The life-threatening nature of anaphylactic reactions has increased interest in discovering new biomarkers that could improve diagnosis and prevention. However, the diverse nature of the clinical features and the etiology and pathogenesis of anaphylaxis hinder the identification of valuable molecular indicators of disease. Most studies on anaphylaxis focus on the immune system. Anaphylactic reactions are characterized primarily by IgE-mediated activation of mast cells and basophils and release of mediators. Determination of serum tryptase levels is the main in vitro test used to confirm the reaction, although there are no biomarkers that can predict it. Nevertheless, recent research has postulated that alternative pathways, cell types, and systems are involved. Consequently, various molecular products have been explored and considered potential biomarkers, although none of them are yet used in clinical practice. The products that are altered in patients with anaphylaxis include vasoactive agents, proteases, proteoglycans, lipids, interleukins, cytokines, products of the complement-contact and coagulation systems, circulating proteins, extracellular vesicles, microRNAs, and metabolites. The recognition of biological processes and molecular pathways affecting the microenvironments involved in anaphylaxis will considerably improve clinical practice and the identification of better molecular markers. We offer a broad review of the various mediators described in anaphylaxis, consider their usefulness as potential biomarkers of this pathological event, and examine their role in the molecular basis of the reaction (AU)

A paper-based ELISA for rapid sensitive determination of anaphylaxis-related MRGPRX2 in human peripheral blood.

Mas-related G-protein-coupled receptor X2 (MRGPRX2) has recently been reported to be associated with anaphylaxis. Detection of MRGPRX2 levels in human peripheral blood might serve as a powerful tool for predicting the predisposition of patients to anaphylactic reactions. For rapid measurement of MRGPRX2, we established a paper-based double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) using mouse monoclonal antibody and horseradish peroxidase (HRP)-labelled rabbit polyclonal antibody as capture antibody and detection antibody, respectively. We avoided chemical functionalization of the cellulose paper by introducing bovine serum albumin (BSA) to provide COOH and NH2 groups for covalent immobilization of the capture antibody. Through amide condensation, a two-layer immobilization strategy was applied with BSA-BSA and BSA-capture antibody networks as the first and second layers, respectively. This strategy improved the quantity, activity and stability of the immobilized antibody. We then established a paper-based ELISA to detect MRGPRX2 in human peripheral blood. Our method is less laborious, easier to implement, and more cost-effective than conventional ELISA, while offering similar sensitivity, specificity, and accuracy. Therefore, it could serve as an innovative clinical point-of-care diagnostic tool, especially in areas that lack advanced clinical equipment.

MRGPRX2 and Adverse Drug Reactions.

Many adverse reactions to therapeutic drugs appear to be allergic in nature, and are thought to be triggered by patient-specific Immunoglobulin E (IgE) antibodies that recognize the drug molecules and form complexes with them that activate mast cells. However, in recent years another mechanism has been proposed, in which some drugs closely associated with allergic-type events can bypass the antibody-mediated pathway and trigger mast cell degranulation directly by activating a mast cell-specific receptor called Mas-related G protein-coupled receptor X2 (MRGPRX2). This would result in symptoms similar to IgE-mediated events, but would not require immune priming. This review will cover the frequency, severity, and dose-responsiveness of allergic-type events for several drugs shown to have MRGPRX2 agonist activity. Surprisingly, the analysis shows that mild-to-moderate events are far more common than currently appreciated. A comparison with plasma drug levels suggests that MRGPRX2 mediates many of these mild-to-moderate events. For some of these drugs, then, MRGPRX2 activation may be considered a regular and predictable feature after administration of high doses.

Clinical significance of plasma PAF acetylhydrolase activity measurements as a biomarker of anaphylaxis: Cross-sectional study.

INTRODUCTION: Platelet-activating factor (PAF) has a direct role as a mediator in the pathogenesis of various disorders with an inflammatory component, including those with allergic aetiology. The peripheral blood concentration of PAF is dynamically regulated by plasma PAF acetylhydrolase (PAF-AH). Previous research suggest that low activity of plasma PAF-AH could be a predictive marker for increased severity of some types of allergic hypersensitivity reactions-especially anaphylaxis. The purpose of the study was to evaluate the association between plasma PAF-AH activity and severity in patients with anaphylactic reactions following a wasp or bee sting. MATERIALS AND METHODS: The study group of 89 patients was divided into two subgroups depending on the increasing severity of the most severe anaphylactic reaction in the past, which was assessed according to the Müller's scale. The first subgroup included participants with a history of hypersensitivity reactions up to grade II. The second subgroup consisted of patients who have experienced at least one grade III or IV reactions in the past. A control group of 20 people was established. Plasma PAF-AH activity was measured using a colorimetric method. RESULTS: It has been observed that plasma activity of platelet-activating factor acetylhydrolase was significantly lower in patients with anaphylaxis history compared to the control group with negative atopic history (on average 21.38 nmol/min/ml for the control group, 9.47 nmol/min/ml for the first subgroup and 10.16 nmol/min/ml for the second subgroup, in both cases p < 0.0001). CONCLUSION: The plasma activity of PAF-AH is a promising parameter that can help to distinguish a group of patients not threatened with development of anaphylaxis and not requiring laborious or expensive prophylactic procedures.

Hereditary Alpha-Tryptasemia: a Commonly Inherited Modifier of Anaphylaxis.

PURPOSE OF REVIEW: Hereditary alpha-tryptasemia (HαT) is an autosomal dominant genetic trait and a common cause of elevated basal serum tryptase in Western populations. It is a risk factor for severe anaphylaxis among individuals with venom allergy and an established modifier of anaphylaxis and mast cell mediator-associated symptoms among patients with systemic mastocytosis. Understanding the physiology of tryptases and how this may relate to the clinical features associated with HαT is the first step in identifying optimal medical management and targets for novel therapeutics. RECENT FINDINGS: HαT prevalence is increased in both clonal and non-clonal mast cell-associated disorders where it augments symptoms of immediate hypersensitivity, including anaphylaxis. The unique properties of naturally occurring α/ß-tryptase heterotetramers may explain certain elements of phenotypes associated with HαT, though additional mechanisms are being evaluated. This review provides an overview of the clinical and translational studies that have identified HαT as a modifier of mast cell-associated disorders and anaphylaxis and discusses mechanisms that may potentially explain some of these clinical findings.

Interference of hemolysis on the postmortem biochemical analysis of IgE by ECLIA.

Forensic diagnosis of anaphylactic shock is a challenging task in forensic practice due to the lack of characteristic morphological changes. Postmortem analysis of serum IgE can provide helpful information for determining anaphylaxis. However, postmortem serum always suffers from hemolysis. To investigate the interference of hemolysis on postmortem analysis of total IgE by electrochemiluminescent immunoassay (ECLIA) and verify the suitability of the commercially available ECLIA kit for postmortem hemolyzed blood with the dilution-correction method, different levels of hemolyzed serum were prepared to evaluate the interference of hemolysis. A linear regression analysis was then performed on the concentration of total IgE in the completely hemolyzed blood and the corresponding serum. Our results indicated that hemolysis negatively interfered with the total IgE analysis by ECLIA and the interference (|Bias%|) increased with increasing levels of hemolysis. After controlling for |Bias%| by dilution, the test concentration of total IgE in the completely hemolyzed blood was still significantly lower than that in the serum (P < 0.05) and resulted in eight false-negative cases. A strong correlation was observed between the test concentration of total IgE in the completely hemolyzed blood and that in the serum (r = 0.983). After correction by the regression formula, the corrected concentration revealed no significant differences and exhibited the same diagnostic ability, compared with the serum total IgE concentration. These results indicate that the completely hemolyzed blood is not recommended for postmortem analysis of total IgE directly. The dilution-correction method might have potential utility in forensic practice for evaluating serum total IgE concentrations.

Idiopathic Anaphylaxis: a Perplexing Diagnostic Challenge for Allergists.

PURPOSE OF REVIEW: The aim of this systematic review is to present the proposed theories of pathogenesis for idiopathic anaphylaxis (IA), to discuss its classification, its diagnostic approach, and management. RECENT FINDINGS: IA represents a major diagnostic challenge and is diagnosed when excluding the possible identifiable triggers of anaphylaxis. The current research, however, revealed that certain conditions including mastocytosis, mast cell activation syndromes, and hereditary alpha tryptasemia can masquerade and overlap with its symptomatology. Also, newly identified galactose-alpha-1,3-galactose mammalian red meat allergy has recently been recognized as underlying cause of anaphylaxis in some cases that were previously considered as IA. IA comprises a heterogenous group of conditions where, in some cases, inherently dysfunctional mast cells play a role in pathogenesis. The standard trigger avoidance strategies are ineffective, and episodes are unpredictable. Therefore, prompt recognition and treatment as well as prophylaxis are critical. The patients should always carry an epinephrine autoinjector.

Hereditary alpha-tryptasemia in 101 patients with mast cell activation-related symptomatology including anaphylaxis.

BACKGROUND: Hereditary alpha-tryptasemia (HαT) is an autosomal dominant genetic trait characterized by multiple copies of the alpha-tryptase gene at the TPSAB1 locus. Previously described symptomatology involves multiple organ systems and anaphylaxis. The spectrum of mast cell activation symptoms is unknown, as is its association with specific genotypes. OBJECTIVE: To describe clinical, laboratory, and genetic characteristics of patients referred for the evaluation of mast cell activation-related symptoms and genotype-confirmed HαT. METHODS: We retrospectively describe clinical characteristics, baseline tryptase, and tryptase genotype in 101 patients. Patients were referred for mast cell activation-related symptoms and underwent genotyping to confirm diagnosis of HαT. RESULTS: Of 101 patients, 80% were female with average tryptase of 17.2 ng/mL. Tryptase was less than 11.4 ng/mL in 8.9% and greater than 20 ng/mL in 22.3% (range 6.2-51.3 ng/mL). KIT D816V mutation was negative in all subjects tested. 2α:3ß was the most common genotype but did not correlate with tryptase levels. Unprovoked anaphylaxis was noted in 57% of the subjects with heterogeneous genotypes. Most common symptoms include gastrointestinal, cutaneous, psychiatric, pulmonary, cardiovascular, and neurologic. A total of 85% of patients were taking H1- or H2-antihistamines with partial symptom relief. Omalizumab was effective at suppressing anaphylaxis or urticaria in 94% of the patients. CONCLUSION: HαT encompasses a broad range of baseline tryptase and should be considered in patients with symptoms of mast cell activation and tryptase levels greater than 6.2 ng/mL. Patients may present with complex symptomatology including cutaneous, gastrointestinal, neurologic, and psychiatric symptoms and anaphylaxis, some of which respond to omalizumab.

Kidney-bean (Phaseolus Vulgaris) Dependent, Exercise-induced Anaphylaxis in Patients Comorbid with Mugwort (Artemisia Vulgaris) Pollinosis.

Background: The cross-reactive allergen between mugwort (Artemisia vulgaris) and kidney bean (Phaseolus vulgaris) has not yet been identified.Methods: A total of 24 patients were included in this study. The sera of patients were analyzed for the concentrations of specific IgE antibodies. The allergenicity and cross-reactivity were investigated by Western blotting and immunoblot inhibitory experiments.Results: The immunoblotting indicated the binding of patients' IgE to crude mugwort extract at ~26 kDa protein (15 cases), ~60 kDa (15 cases), and 10-15 kDa proteins (12 cases). The results of the immunoblot-inhibition assay showed that kidney bean seed extract inhibited specific IgE binding to mugwort at 10-15 kDa, ~26 kDa, and ~60 kDa in 4 (16.7%), 1 (4.2%) and 2 (8.3%) cases, respectively. On the other hand, mugwort extract was demonstrated to inhibit specific IgE binding to kidney bean seed at 10-15 kDa, 15-20 kDa, ~30 kDa, and 60 kDa in 1 (4.2%), 3 (12.5%), 4 (16.7%), and 3 (12.5%) cases, respectively.Conclusion: The 26-30 kDa, 10-15 kDa, and 60 kDa proteins are potential causative agents of the cross-reactivity between mugwort and kidney beans. The findings of this study improved the current understanding on the allergenicity of kidney beans and would provide insights into the refinement of treatment strategy for anaphylaxis.

Induction of Peanut Allergy Through Inhalation of Peanut in Mice.

Peanut (PN) allergy is a common life-threatening disease; however, our knowledge on the immunological mechanisms remains limited. Here, we describe the first mouse model of inhalation-driven peanut allergy. We administered PN flour intranasally to naïve wild-type mice twice a week for 4 weeks, followed by intraperitoneal challenge with PN extract. Exposure of mice to PN flour sensitized them without addition of adjuvants, and mice developed PN-specific IgE, IgG1, and IgG2a. After challenge, mice displayed lower body temperature and other clinical signs of anaphylaxis. This inhalation model is an ideal system to allow for future examination of immunological mechanisms critical for the development of PN allergy.

Induction of Hypersensitivity with Purified Beta-Lactoglobulin as a Mouse Model of Cow's Milk Allergy.

Cow's milk allergy is one of the most prevalent food allergies in both children and adults. As dairy products are common dietary ingredients and the prevalence of chronic conditions is on the rise, milk allergy is a growing public health concern. To elucidate underlying mechanisms and develop therapeutic strategies, reliable animal models are essential research tools. Sensitization to a milk protein is the principal procedure for establishing animal models of cow's milk allergy. However, the methods of sensitization vary from laboratory to laboratory, using different milk proteins with different amounts, routes, and durations of allergen exposure during sensitization of varying sex and strains of mice, likely resulting in diverse immunological and physical responses. Furthermore, the sources and potential impurities of milk protein may also produce variable responses. Thus, standardization of sensitization protocol is important, particularly when results are compared across studies. Here, we describe a method to generate a mouse model of cow's milk allergy using purified ß-lactoglobulin as the milk allergen with cholera toxin as an adjuvant in a 5-week oral sensitization protocol.

Medicolegal Implications of Biphasic Anaphylaxis.

ABSTRACT: Biphasic anaphylaxis is an uncommon IgE-mediated condition whose pathophysiological mechanisms, risk factors, and predictive signs are not properly understood. Fortunately, the lethality of biphasic anaphylaxis, although probably underestimated, is low. Preventive clinical measures for biphasic anaphylaxis are neither standardized nor commonly applied. Furthermore, there are no laboratory protocols or anaphylactic markers to help identify the onset of biphasic anaphylaxis in clinical settings. The aim of this review is to highlight the medicolegal difficulties facing coroners and forensic pathologists in terms of the diagnosis and assessment of harm for victims and survivors of biphasic anaphylaxis.

Differences Between Central and Peripheral Postmortem Tryptase Levels.

ABSTRACT: Postmortem tryptase is a commonly used biochemical test to aid in the diagnosis of fatal anaphylaxis, which is currently recommended to be sampled from peripheral (femoral) veins because of a research showing comparatively elevated levels from central blood sources. Previous studies have used nonstandardized or nondocumented sampling methods; however, more recent research demonstrates that tryptase levels may vary depending on the sampling method. This study used the recommended sampling method of aspirating the femoral vein after clamping and compared in a pairwise comparison with aspiration of central venous and arterial blood sources (inferior vena cava and aorta) in 2 groups of 25 nonanaphylactic deaths. We found no statistically significant differences in postmortem tryptase between central and femoral vein blood; however, sporadic outliers in central blood (particularly aortic blood reaching levels above documented cutoffs for fatal anaphylaxis) were observed. Our findings provide evidence for the existing recommendations that femoral vein blood remains the preferred sample for postmortem tryptase over central blood.

Correlation of L-asp Activity, Anti-L-asp Antibody, Asn and Gln With Adverse Events Especially Anaphylaxis Risks in PEG-asp-Contained Regime Treated Pediatric ALL Patients.

OBJECTIVE: This study aimed to investigate the correlation of L-asparaginase (L-asp) activity, anti-L-asp antibody, asparagine and glutamine levels with the risks of adverse events (AEs), especially anaphylaxis, in pediatric acute lymphoblastic leukemia (ALL) patients who underwent polyethylene glycol-conjugated L-asp (PEG-asp)-contained treatment. METHODS: Plasma samples were collected from 91 pediatric ALL patients who underwent PEG-asp-contained treatment on the 7th day after drug administration. Plasma L-asp activity, anti-L-asp antibody level, asparagine level and glutamine level were detected. Meanwhile, AEs related to PEG-asp administration were recorded. RESULTS: AEs occurred in 13 (14.3%) patients, among which 7 (7.7%) patients had anaphylaxis, while another 6 patients had non-anaphylaxis AEs (including 4 (4.4%) patients who had acute pancreatitis, 1 (1.1%) patient who had abdominal pain and diarrhea, as well as 1 (1.1%) patient who had nausea and vomiting). L-asp activity was decreased, while asparagine and glutamine levels were increased in patients with AEs compared to patients without AEs, and ROC curves showed that they were correlated with higher AEs risk. Notably, further analyses revealed that L-asp activity, anti-L-asp antibody, asparagine and glutamine levels were highly correlated with anaphylaxis risk, but they were not associated with the risk of non-anaphylactic AEs. CONCLUSION: The measurement of L-asp activity, anti-L-asp antibody level, asparagine level and glutamine level might assist the prevention of anaphylaxis-related AEs in pediatric ALL patients who underwent PEG-asp-contained treatment.