Although 4 mast cell mediators can be routinely measured, the results of initial testing to evaluate symptoms of mast cell activation have not been widely reported.
We examined the results of mast ...cell mediator tests used to assess patients with mast cell activation symptoms during a 5-year time span.
After excluding patients with alternative diagnoses, records of 108 patients were reviewed for initial mediator test results. Mediators included serum tryptase plus urinary N-methyl histamine (N-MH), leukotriene (LT)E4, and 11β-prostaglandin (PG) F2α or 2,3-dinor-11β-PGF2α (BPG).
Most commonly, either a single measured elevation of 1 mediator (48.1%) or elevations of 2 (33.3%) mediators was found at baseline, during symptoms or at both time points. Elevated levels of a single mediator in order of frequency were: BPG > tryptase > LTE4 > N-MH, and for two mediators: BPG + tryptase (n = 16 cases) > BPG + LTE4 (n = 9) > BPG + N-MH (n = 6). Elevations in 3 mediators (n = 8) or 4 mediators (n = 2) were much less frequent. Monoclonal mast cell activation syndrome (n = 6), and systemic and cutaneous mastocytosis (n = 4) were also infrequent. Baseline plus symptom-associated tryptase values were obtained in only 7 patients.
This survey suggests that elevations of 1 or 2 mediators are the most common (total 81.4% of cases) findings from initial tests for mast cell activation. Elevated levels of BPG were most commonly found both singly and in combination with other mediators, followed by the finding of elevated levels of tryptase. Baseline plus symptom-associated tryptase levels were measured in only a minority of patients.
Mast cell activation syndrome (MCAS) is a condition characterized by recurrent episodes of clinically relevant, systemic, severe reactions to mast cell (MC)-derived mediators released in the context ...of anaphylaxis or another acute MC-related event. It is important to document MC involvement in these reactions in order to establish the diagnosis MCAS. The most specific and reliable marker of systemic MC activation is an acute and substantial event-related (transient) increase in the serum tryptase level over the individual's baseline value. However, the baseline level of tryptase varies depending on the underlying disease and the genetic background. For example, an estimated 3-5% of healthy individuals exhibit duplications or multiple copies of the TPSAB1 gene encoding for alpha-tryptase, and over 30% of all patients with myeloid neoplasms, including mastocytosis, have elevated basal tryptase levels. Therefore, it is of utmost importance to adjust the event-related diagnostic (MCAS-confirming) increase in tryptase over the individual baseline in a robust approach. To address this challenge, the 20% + 2 formula was proposed by the consensus group in 2012. Since then, this approach has been validated in clinical practice by independent groups and found to be sound. In the current article, we discuss the emerging importance and value of the 20% + 2 formula in clinical practice and its role as a criterion of severe systemic MC activation and MCAS.
Eosinophilia is an important indicator of various neoplastic and nonneoplastic conditions. Depending on the underlying disease and mechanisms, eosinophil infiltration can lead to organ dysfunction, ...clinical symptoms, or both. During the past 2 decades, several different classifications of eosinophilic disorders and related syndromes have been proposed in various fields of medicine. Although criteria and definitions are, in part, overlapping, no global consensus has been presented to date. The Year 2011 Working Conference on Eosinophil Disorders and Syndromes was organized to update and refine the criteria and definitions for eosinophilic disorders and to merge prior classifications in a contemporary multidisciplinary schema. A panel of experts from the fields of immunology, allergy, hematology, and pathology contributed to this project. The expert group agreed on unifying terminologies and criteria and a classification that delineates various forms of hypereosinophilia, including primary and secondary variants based on specific hematologic and immunologic conditions, and various forms of the hypereosinophilic syndrome. For patients in whom no underlying disease or hypereosinophilic syndrome is found, the term hypereosinophilia of undetermined significance is introduced. The proposed novel criteria, definitions, and terminologies should assist in daily practice, as well as in the preparation and conduct of clinical trials.
Clinical phenotype in systemic mastocytosis (SM) is markedly variable, which complicates prognostication and decision making regarding the choice and timing of therapy. In a retrospective study of ...342 consecutive adult patients with SM seen at the Mayo Clinic between 1976 and 2007, disease subdesignation according to the World Health Organization (WHO) proposal was indolent (ISM) in 159 (46%), with associated clonal hematologic non–mast cell lineage disease (SM-AHNMD) in 138 (40%), aggressive (ASM) in 41 (12%), and mast cell leukemia in 4 (1%). KITD816V was detected in bone marrow–derived DNA by allele-specific polymerase chain reaction (PCR) in 68% of 165 patients evaluated (ISM, 78%; ASM, 82%; SM-AHNMD, 60%; P = .03); JAK2V617F was detected in 4%, all in SM-AHNMD. Compared with those with nonindolent SM, life expectancy in ISM was superior and not significantly different from that of the age- and sex-matched US population. In addition, multivariable analysis identified advanced age, weight loss, anemia, thrombocytopenia, hypoalbuminemia, and excess bone marrow blasts as independent adverse prognostic factors for survival. The current study validates the prognostic relevance of the WHO subclassification of SM and provides additional information of value in terms of both risk stratification and interpretation of clinical presentation and laboratory results.
Patients with systemic mastocytosis often have symptoms of mast cell activation, which is associated with elevated levels of urinary mast cell mediator metabolites. Patients with hereditary ...α-tryptasemia (HαT) may present with symptoms of mast cell activation. Whether levels of mast cell mediators are elevated in this patient population is not known.
The purpose of this study was to determine whether patients with HαT and symptoms of mast cell activation have elevated levels of urinary mediators and compare the levels with those in patients with systemic mastocytosis.
We retrospectively analyzed mast cell mediators in 63 patients with a confirmed diagnosis of HαT, 20 patients with a confirmed diagnosis of indolent systemic mastocytosis (ISM), and 23 healthy controls. All patients were referred to the Brigham and Women’s Hospital Mastocytosis Center or the Mayo Clinic for evaluation of mast cell activation disorders.
Our population was predominantly female (85.7%) with an average age of 53.8 years. The average baseline serum tryptase level was significantly higher in patients with ISM than in those with HαT (65.9 vs 19.3 ng/mL P < .01). When compared with patients with HαT, those with ISM had statistically significant increases in their levels of urinary N-methylhistamine (P < .01) and 2,3-dinor-11β-prostaglandin F2α (P < .05).
Patients with symptomatic HαT do not have elevations of mast cell urinary metabolites, suggesting that granule- and membrane-derived mediators may not drive symptoms in HαT.
Mast cell (MC) disease has long been thought to be just the rare disease of mastocytosis (in various forms, principally cutaneous and systemic), with aberrant MC mediator release at symptomatic ...levels due to neoplastic MC proliferation. Recent discoveries now show a new view is in order, with mastocytosis capping a metaphorical iceberg now called "MC activation disease" (MCAD, i.e. disease principally manifesting inappropriate MC activation), with the bulk of the iceberg being the recently recognized "MC activation syndrome" (MCAS), featuring inappropriate MC activation to symptomatic levels with little to no inappropriate MC proliferation. Given increasing appreciation of a great menagerie of mutations in MC regulatory elements in mastocytosis and MCAS, the great heterogeneity of MCAD's clinical presentation is unsurprising. Most MCAD patients present with decades of chronic multisystem polymorbidity generally of an inflammatory ± allergic theme. Preliminary epidemiologic investigation suggests MCAD, while often misrecognized, may be substantially prevalent, making it increasingly important that practitioners of all stripes learn how to recognize its more common forms such as MCAS. We review the diagnostically challenging presentation of MCAD (with an emphasis on MCAS) and current thoughts regarding its biology, epidemiology, natural history, diagnostic evaluation, and treatment.
Key messages
Recent discoveries show a new view of the realm of mast cell disease is in order, with mastocytosis capping a metaphorical iceberg now termed "MC activation disease" (MCAD, i.e. disease principally manifesting inappropriate MC activation) and with the bulk of the iceberg being comprised of the recently recognized "MC activation syndrome" (MCAS), featuring inappropriate MC activation to symptomatic levels with little to no inappropriate MC proliferation.
Most MCAD patients present with decades of chronic multisystem polymorbidity generally of an inflammatory ± allergic theme, but diagnostic recognition is challenged by great heterogeneity of clinical presentation which may be due to great underlying mutational heterogeneity in assorted mast cell regulatory elements.
Although few biomarkers predictive of helpful therapy are yet available, most MCAD patients are able to eventually identify significantly helpful therapy by persistently and methodically stepping through trials of the many treatments shown helpful across this patient population.
Providers caring for patients with mastocytosis are tasked with the decision to consider therapeutic options. This can come with some trepidation because information available in the public domain ...lists numerous mast cell (MC) activators based on data that do not discriminate between primates, rodents, and MC lines; do not consider dosage; and do not take into account previous exposure and resultant clinical findings. This being said, there is support in the literature for an enhanced MC response in some patients with mastocytosis and in cases in which there is a greater incidence of adverse reactions associated with certain antigens, such as venoms and drugs. Thus this report provides a comprehensive guide for those providers who must decide on therapeutic options in the management of patients with clonal MC disease.
Mast cells leave evidence, a "fingerprint," of their participation in acute and chronic clinical events. That fingerprint is an elevation, either chronic or acute, in levels of their secreted ...mediators or their metabolites. Of these, only serum tryptase is currently one of the diagnostic criteria for systemic mastocytosis or mast cell activation. Combinations of easily obtained and quantified urinary mast cell mediator metabolite levels correlate well with bone marrow findings of systemic mastocytosis. By inhibiting synthesis of or blockading receptors to the elevated mast cell mediator, relief of clinical symptoms can often be achieved.
Background Hypereosinophilic syndrome (HES) is a heterogeneous group of rare disorders defined by persistent blood eosinophilia ≥1.5 × 109 /L, absence of a secondary cause, and evidence of ...eosinophil-associated pathology. With the exception of a recent multicenter trial of mepolizumab (anti–IL-5 mAb), published therapeutic experience has been restricted to case reports and small case series. Objective The purpose of the study was to collect and summarize baseline demographic, clinical, and laboratory characteristics in a large, diverse cohort of patients with HES and to review responses to treatment with conventional and novel therapies. Methods Clinical and laboratory data from 188 patients with HES, seen between January 2001 and December 2006 at 11 institutions in the United States and Europe, were collected retrospectively by chart review. Results Eighteen of 161 patients (11%) tested were Fip1-like 1–platelet-derived growth factor receptor α ( FIP1L1-PDGFRA ) mutation—positive, and 29 of 168 patients tested (17%) had a demonstrable aberrant or clonal T-cell population. Corticosteroid monotherapy induced complete or partial responses at 1 month in 85% (120/141) of patients with most remaining on maintenance doses (median, 10 mg prednisone equivalent daily for 2 months to 20 years). Hydroxyurea and IFN-α (used in 64 and 46 patients, respectively) were also effective, but their use was limited by toxicity. Imatinib (used in 68 patients) was more effective in patients with the FIP1L1-PDGFRA mutation (88%) than in those without (23%; P < .001). Conclusion This study, the largest clinical analysis of patients with HES to date, not only provides useful information for clinicians but also should stimulate prospective trials to optimize treatment of HES.
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