Mast Cell Activation During Suspected Perioperative Hypersensitivity: A Need for Paired Samples Analysis

A US-Based Multicenter Retrospective Report of Perioperative Anaphylaxis, 2010-2021

BACKGROUND

US-based perioperative anaphylaxis (POA) studies are limited to single-center experiences. A recent report found that a serum acute tryptase (sAT) >9.8 ng/mL or mast cell activation (MCA) can predict POA causal agent identification. Urinary mast cell mediator metabolites (uMC) have not been studied in POA.

OBJECTIVE

To analyze the epidemiologic data of POA, to determine if sAT or MCA can predict suspected causal agent identification, and to evaluate uMC utility in POA.

METHODS

This study is a retrospective multicenter review of POA cases that were subcategorized by suspected causal agent identification status. sAT, MCA (defined as sAT >2 + 1.2 × serum baseline tryptase), and uMC (N-methylhistamine [N-MH], 11β-prostaglandin-F2α [11β-PGF2α], leukotriene E4 [LTE4]) were recorded.

RESULTS

Of 100 patients (mean age 52 [standard deviation 17] years, 94% adult, 50% female, 90% White, and 2% Hispanic) with POA, 73% had an sAT available, 41% had MCA, 16% had uMC available, and 50% had an identifiable suspected cause. POA cases with an identifiable suspected cause had a positive MCA status (100% vs 78%; P = .01) compared with POA with an unidentifiable cause. An elevated median sAT did not predict causal agent identification. Positive uMC were not associated with suspected causal agent identification during POA. Patients with positive uMC had a higher median sAT (30 vs 6.45 ng/mL; P = .001) and MCA status (96% vs 12%; P = .001) compared with negative uMC patients. Patients with POA had an elevated acute/baseline uMC ratios: 11β-PGF2α ratio > 1.6, N-MH ratio >1.7, and LTE4 ratio >1.8.

CONCLUSIONS

The presence of MCA in POA is associated with suspected causal agent identification. Positive uMC possibly correlate with a higher sAT level and MCA status but require further study. The authors suggest applying an acute/baseline uMC ratio (11β-PGF2α ratio >1.6, N-MH ratio >1.7, and LTE4 ratio >1.87) in patients with POA for MCA when a tryptase level is inconclusive during POA evaluations.

Paediatric perioperative hypersensitivity: the performance of the current consensus formula and the effect of uneventful anaesthesia on serum tryptase

Background

Paired sampling of acute (aST) and basal (bST) serum tryptase has been recommended when investigating patients with a suspected perioperative hypersensitivity (POH) reaction. In the current consensus formula, an aST value exceeding (1.2×bST+2) confirms mast cell activation. The current consensus formula has been validated in adults but not in children.

Methods

We prospectively included 96 children who underwent uneventful anaesthesia and sampled serum tryptase at baseline and 60-90 min after induction. Tryptase changes were then compared with those in 94 children with suspected POH who were retrospectively included from four reference centres in Belgium, France, and Denmark.

Results

We observed a median decrease in serum tryptase during uneventful anaesthesia of 0.41 μg L-1 (-15.9%; P<0.001). The current consensus formula identified mast cell activation in 31.9% of paediatric POH patients. After generating receiver operating characteristic curves through 100 repeated five-fold cross-validation, aST>bST+0.71 was identified as the optimal cut-off point to identify mast cell activation. This new paediatric formula has higher sensitivity than the current consensus formula (53.2% vs 31.9%, P<0.001) with a specificity of 96.9%. Analysis in the subpopulation where a culprit was identified and in grade 3-4 reactions similarly yielded higher sensitivity for the new paediatric formula when compared with the current consensus formula (85.3% vs 61.8%; P=0.008 and 78.0% vs 48.8%; P<0.001, respectively). Internally cross-validated sensitivity and specificity were 53.3% and 93.3%, respectively.

Conclusions

This is the first study suggesting the need for an adjusted formula in children to identify perioperative mast cell activation as tryptase is significantly lowered during uneventful anaesthesia. We propose a new formula (aST>bST+0.71) which performs significantly better than the current consensus formula in our multicentric paediatric population.

Reversible Elevation of Tryptase Over the Individual's Baseline: Why is It the Best Biomarker for Severe Systemic Mast Cell Activation and MCAS?

PURPOSE OF REVIEW

Mast cell (MC) activation syndromes (MCAS) are conditions defined by recurrent episodes of severe systemic anaphylaxis or similar systemic events triggered by MC-derived mediators that can be measured in biological fluids. Since some symptoms of MC activation may occur due to other, non-MC etiologies and lead to confusion over diagnosis, it is of crucial importance to document the involvement of MC and their products in the patients´ symptomatology.

RECENT FINDINGS

The most specific and generally accepted marker of severe systemic MC activation is an event-related, transient increase in the serum tryptase level over the individual baseline of the affected individual. However, baseline concentrations of serum tryptase vary among donors, depending on the genetic background, age, kidney function, and underlying disease. As a result, it is of critical importance to provide a flexible equation that defines the diagnostic increase in tryptase qualifying as MCAS criterion in all patients, all situations, and all ranges of baseline serum tryptase. In 2012, the consensus group proposed the 120% + 2 ng/ml formula, which covers the great majority of groups, including cases with low, normal, or elevated basal serum tryptase level. This formula has been validated in subsequent studies and has proven to be a robust and consistent diagnostic criterion of MCAS. The present article is discussing the impact of this formula and possible limitations as well as alternative markers and mediators that may be indicative of MCAS.

Diagnostic Significance of Tryptase for Suspected Mast Cell Disorders

Tryptase has proven to be a very useful and specific marker to demonstrate mast cell activation and degranulation when an acute (i.e., within 4 h after the event) and baseline value (i.e., at least 24 h after the event) are compared and meet the consensus formula (i.e., an increase of 20% + 2). The upper limit of normal determined by the manufacturer is 11.4 ng/mL; however, this boundary has been the subject of debate. According to ECNM and AIM experts, the normal range of baseline tryptase should be 1 to 15 ng/mL. A genetic trait, hereditary alpha tryptasemia, characterized by an increased alpha coding TPSAB1 copy number is associated with a baseline value above 8 ng/mL. Elevated tryptase can also be found in chronic kidney disease, obesity, and hematological neoplasms. A tryptase > 20 ng/mL serves as a minor criterion to diagnose systemic mastocytosis and an increase in tryptase > 20% + 2 during an acute event is a required criterion in the diagnosis of mast cell activation syndrome. The goal of this review is to demonstrate the (in)significance of tryptase using some clinical vignettes and to provide a practical guide on how to manage and interpret an elevated tryptase level.

Serum tryptase and drug hypersensitivity: why, how and what? A systematic review

PURPOSE OF REVIEW

Serum tryptase, a mast cell marker, provides clues for the mechanism, severity, and management of drug hypersensitivity induced by immunoglobulin E dependent or independent mast cell activation.

RECENT FINDINGS

The interpretation of serum tryptase levels has been challenged during the last 2 years by major advances in tryptase genetics and their rapid incorporation into clinical practice. On the contrary, new pathophysiological insight into nonmast cell-dependent immediate hypersensitivity has been gained.

SUMMARY

This review provides up-to-date information on the pathophysiology and recommended use and interpretation of tryptase in the context of drug hypersensitivity reactions as a function of their endotype.

Perioperative anaphylaxis: when the allergological work-up goes negative

PURPOSE OF REVIEW

Perioperative anaphylaxis (POA) is rare but is associated with significant morbidity and mortality. Patients are referred to the allergist to identify the mechanism of the reaction, the causative agent and make recommendations regarding subsequent anaesthesia. Despite a well conducted allergological evaluation, the causative agent is not found in 30-60% of these reactions, leaving patients without a well established diagnosis.

RECENT FINDINGS

Several mechanisms can induce POA. In addition to the well known IgE-mediated reactions, IgG-mediated reaction, MRGPR-X2-related reaction or nonspecific histamine release may be involved. These situations are not easily assessed by the allergological workup.

SUMMARY

When the allergological workup is negative, the situation should be reassessed with the team present at the time of the reaction to confirm the reality of the hypersensitivity reaction and to search for a possible differential diagnosis. If POA is confirmed, the allergological evaluation should be repeated, ensuring proper execution according to current guidelines and including the search for hidden allergens. Specific IgE assays or basophil activation tests may be of interest. In case of negative results, a closely monitored drug challenge test, in coordination with the anaesthesia teams, may be useful to avoid the exclusion of any drug injected during the reaction.

Investigating the optimal diagnostic value of histamine for diagnosing perioperative hypersensitivity: a prospective, observational study

Although several guidelines recommend measuring blood tryptase and histamine concentrations to diagnose perioperative anaphylaxis (POA), tryptase measurement is more common. The appropriate timing of blood collection and the diagnostic threshold for histamine measurement are still controversial. To address these issues, histamine concentrations in patients with anaphylaxis and those with anaphylaxis-uncertain were compared in our previous study, the Japanese Epidemiologic Study for Perioperative Anaphylaxis (JESPA). However, because we could not rule out the possibility that the anaphylactic-uncertain group included anaphylactic patients, histamine concentrations were measured in patients who underwent general anesthesia with no complications as controls in the present study. Histamine levels were measured at anesthesia induction (baseline), 30 min (first point), and 2 h (second point) after the start of surgery in 30 control patients. Histamine concentrations in controls were lower than in patients with POA in JESPA at the first and second points. At the first point, a threshold of 1.5 ng/ml resulted in sensitivity of 77% and specificity of 100%. A threshold of 1.1 ng/ml at the second point resulted in sensitivity of 67% and specificity of 87%. Measurement of histamine concentrations within two hours after symptom onset might help diagnose POA.

A quarter of a century fundamental and translational research in perioperative hypersensitivity and anaphylaxis at the Antwerp university hospital, a Belgian Centre of Excellence of the World Allergy Organization

Perioperative hypersensitivity constitutes an important health issue, with potential dramatic consequences of diagnostic mistakes. However, safe and correct diagnosis is not always straightforward, mainly because of the application of incorrect nomenclature, absence of easy accessible in-vitro/ex-vivo tests and uncertainties associated with the non-irritating skin test concentrations. In this editorial we summarize the time line, seminal findings, and major realizations of 25 years of research on the mechanisms, diagnosis, and management of perioperative hypersensitivity.

Diagnostic value of a medical algorithm for investigation of perioperative hypersensitivity reactions

BACKGROUND

Evaluation of perioperative hypersensitivity (POH) is challenging, and accurate screening tools are needed to optimize the diagnostic process. We aimed to assess and validate the diagnostic value of a published algorithm (using tryptase and clinical presentation) to identify appropriate individuals for further testing for IgE-mediated POH.

METHODS

We analysed the clinical presentation (tryptase elevation, cardiovascular, respiratory, skin involvement) of patients proceeding to testing for possible IgE-mediated POH at a single tertiary referral centre, relative to subsequent skin testing and specific IgE results. Clinical presentations by drug class were also determined.

RESULTS

In 293 consecutive patients, the use of a published algorithm based on one or more of; (i) defined increase in serum tryptase, (ii) involvement of at least two-organ systems, or (iii) presentation with new urticaria and/or angioedema; was highly sensitive [98.8% (CI95: 95.7-99.9%)] but less specific [34.6% (CI95: 25.7-44.4%)] in identifying patients testing positive on skin testing and/or specific IgE. Presentation with cardiovascular symptoms was also sensitive [89.8%(CI95: 84.2-94.0%)], while the combination of respiratory symptoms and increased tryptase was most specific [85.9%(CI95:76.6-92.5%)]. Respiratory involvement was more common in neuromuscular blocking agent allergy, while urticaria/angioedema was more common in antibiotic allergy.

CONCLUSION

The published algorithm (of tryptase rise, two-organ involvement or new urticaria/angioedema) is highly sensitive, and appropriate as a screening tool to identify patients suitable for testing for IgE-mediated POH.

Epidemiology of perioperative anaphylaxis in the United States: new insights but more to learn and do

Gonzalez-Estrada and colleagues report an estimated risk of severe or fatal perioperative anaphylaxis of one in 6,825 procedures during the period 2005-2014. This is slightly higher than that reported previously in France and England. Several predictors of near-fatal and fatal reactions are identified, such as increased age, cancer, and congestive cardiac failure.

Mast cell activation syndrome: is anaphylaxis part of the phenotype? A systematic review

PURPOSE OF REVIEW

Mast cell activation syndrome (MCAS) and anaphylaxis are the result of a spontaneous or triggered pathological degranulation of mast cells (MCs) and might have as substrate normal or pathological MCs (increased burden, aberrant MCs or both).

RECENT FINDINGS

This review summarizes the most recent evidence on immunoglobulin E (IgE)-mediated and non IgE-mediated mechanisms underlying MC activation and degranulation and highlights the importance of standardized diagnostic criteria for MCAS. Application of these criteria implies that in most cases the clinical presentation of MCAS meets the diagnostic criteria for anaphylaxis.

SUMMARY

Integrating clinical parameters and diagnostic test recognition and underlying clonal MC disease are of utmost importance for a patient-tailored approach. Hereditary alpha-tryptasemia can be encountered in context of anaphylaxis, MCAS and primary MC disorders.

Use and Interpretation of Acute and Baseline Tryptase in Perioperative Hypersensitivity and Anaphylaxis

Paired acute and baseline serum or plasma tryptase sampling and determination have recently been included as a mechanistic approach in the diagnostic and management guidelines of perioperative immediate hypersensitivity and anaphylaxis. The timing of this paired sampling is clearly defined in international consensus statements, with the optimal window for acute tryptase sampling between 30 minutes and 2 hours after the initiation of symptoms, whereas baseline tryptase should be measured in a sample collected before the event (preop) or at least 24 hours after all signs and symptoms have resolved. A transient elevation of the acute tryptase level greater than [2 + (1.2 × baseline tryptase level)] supports the involvement and activation of mast cells. Here, we provide the clinical, pathophysiological, and technical rationale for the procedure and interpretation of paired acute and baseline tryptase. Clinical examples, up-to-date knowledge of hereditary α-tryptasemia as a frequent cause of baseline tryptase of 7 μg/L and higher, mastocytosis, other clonal myeloid disorders, cardiovascular or renal failure, and technical improvements resulting in continued lowering of the 95th percentile value are discussed. Clues for improved management of perioperative immediate hypersensitivity and anaphylaxis include (1) sustained dissemination and implementation of updated guidelines; (2) preoperative sample storage for deferred analysis; (3) referral for thorough allergy investigation, screening for mast cell-related disorders, and recommendations for future anesthetic procedures; and (4) sustained collaboration between anesthesiologists, immunologists, and allergists.