Alpha-gal syndrome: when treatment of hypovolemic shock can lead to anaphylaxis.

Delayed anaphylaxis after ingestion of red meat because of galactose-alpha-1,3-galactose (alpha-gal) syndrome has increased in recent years. The mechanism involves an immunoglobulin E reaction to alpha-gal, a molecule found in mammalian meat, dairy products, medications and excipients containing mammalian-derived components, and tick salivary glycans. Sensitization occurs due to the bite of a lone star tick and the transmission of alpha-gal molecules into person's bloodstream. We describe a case of alpha-gal syndrome with severe food, drug, and perioperative allergy in which anaphylaxis with hypovolemic shock occurred immediately after an emergency surgical procedure, when a gelatin-containing drug was injected. This case study confirms that the clinical manifestations of alpha-gal syndrome could be different depending on the route of administration, with immediate reactions if an alpha-gal-containing drug is injected and delayed type allergic manifestations occurring several hours after oral intake. The purpose of this report is to highlight the importance of risk communication in case of exposure to medical products and surgical procedures of patients with alpha-gal syndrome and to encourage drug manufacturers to indicate clearly the origin of excipients in product literature.

Venom Anaphylaxis: Decision Points for a More Aggressive Workup.

Diagnostic testing of patients who present for evaluation of insect venom allergy can involve many levels of investigation. A detailed initial history is critical for diagnosis and prognosis. The severity of previous sting reactions and the presence or absence of urticaria or hypotension predict severe future sting reactions and underlying mast cell disorders. Venom skin tests and specific IgE measurement can confirm the diagnosis but have limited positive predictive value for the frequency and severity of future sting reactions. Testing for serum IgE to recombinant venom component allergens can distinguish true allergy from cross-reactivity to honey bee and yellowjacket venoms. Basophil activation tests can improve the detection of venom allergy and predict the severity of reactions and the efficacy of venom immunotherapy but are limited in availability. An elevated basal serum tryptase level is an important marker for severe sting anaphylaxis and underlying mast cell disorders (eg, hereditary α-tryptasemia and clonal mast cell disease). When there is high suspicion (eg, using the Red Espanola de Mastocytosis score), bone marrow biopsy is the definitive tool to characterize mast cell disorders that are associated with the most severe outcomes in patients with insect sting allergy.

Non-steroidal anti-inflammatory drug-induced anaphylaxis infrequent in 388 patients with mastocytosis: A two-center retrospective cohort study.

Background: Anaphylaxis is a well-known feature of mastocytosis, particularly in relation to hymenoptera venom stings. It is therefore hypothesized that mastocytosis patients may also be predisposed to severe hypersensitivity reactions to certain medications including non-steroidal anti-inflammatory drugs (NSAIDs). For this reason, these patients are usually discouraged from using these drugs. The current study aimed to determine the prevalence and evaluate the severity of NSAID-related hypersensitivity reactions among patients with mastocytosis. Methods: A retrospective study was conducted among a total of 388 (≥18 years old) consecutive patients from two independent European mastocytosis centers, in Sweden and Italy. Patients underwent a thorough allergy work-up where self-reported NSAID-hypersensitivity reactions were re-evaluated by an allergist in the first cohort (202 patients) and results were validated in the second cohort (186 patients). Results: Overall frequency of NSAID-hypersensitivity was 11.3% in the total study cohort. Most patients reacted with cutaneous symptoms (89%), whereas severe hypersensitivity reactions were infrequent with only 11 patients (2.8%) experiencing anaphylaxis. All NSAID-related hypersensitivity reactions had occurred before mastocytosis was diagnosed. There was no difference between the groups regarding gender, baseline tryptase levels or presence of atopy, asthma/rhinitis. Conclusion: Our study indicates an approximate 4-fold increased prevalence of NSAID hypersensitivity among mastocytosis patients compared to the general population. However, most NSAID reactions were limited to the skin as the prevalence of overall anaphylaxis was infrequent. Our results support that mastocytosis patients with a known tolerance to NSAIDs can continue using these medications without special precautions, whereas those with a prior reaction to NSAIDs should undergo thorough allergy work-up, including drug challenges.

Hereditary alpha-tryptasemia.

PURPOSE OF REVIEW: To discuss our evolving knowledge about the genetic variations in human tryptase and recent advances in associated clinical phenotypes. RECENT FINDINGS: Hereditary alpha-tryptasemia (HAT) is an autosomal dominant genetic trait and a common cause of elevated basal serum tryptase (BST) in Western populations. It is a risk factor for severe anaphylaxis and an established modifier of mast cell mediator-associated symptoms among patients with systemic mastocytosis (SM). SUMMARY: The unique properties of naturally occurring alpha/beta-tryptase heterotetramers may explain certain elements of phenotypes associated with HAT. Understanding the physiology of tryptases and how this may relate to the clinical features associated with HAT is the first step in identifying optimal medical management and targets for novel therapeutics.