Allergen specific immunotherapy is safe and effective in patients with systemic mastocytosis and Hymenoptera allergy

Hymenoptera venom immunotherapy: Safety and efficacy of an accelerated induction regimen with depot aluminum adsorbed extracts

Introduction: Hymenoptera venom immunotherapy (VIT) is the only therapy that protects patients with Hymenoptera venom allergy by preventing systemic reactions after a new sting. Various extracts for VIT are available and used. VIT administration consists of an induction phase and a maintenance phase. Depot preparations of Hymenoptera VIT extracts are typically used for cluster and conventional protocols, and the maintenance phase. Many patients with Hymenoptera allergy need to achieve tolerance quickly because of the high risk of re-sting and possible anaphylaxis. Objective: Our study aimed to show the safety and efficacy of an accelerated regimen with depot preparations on aluminum hydroxide by using relatively high starting doses in a heterogeneous group of patients. Methods: The research focused on a group of patients with a history of severe systemic reactions to Hymenoptera stings, with the necessity of swift immunization due to high occupational risks. Aluminum hydroxide depot extracts either of Vepula species or Apis mellifera extracts were used. Results: The induction protocol was started with the highest concentration of depot venom extract of 100,000 standard quality unit and was well tolerated by 19 of 20 patients. Onne patient presented with a mild systemic reaction during the accelerated induction schedule, which was promptly treated with intravenous steroids and intramuscular H1 antihistamine; when switched to a conventional induction protocol, he had a similar reaction but finally reached maintenance with an H1-antagonist premedication. Conclusion: If validated, the accelerated induction protocol by using depot aluminum adsorbed extracts with the highest concentration of venom from the beginning could offer a streamlined and accessible treatment modality for patients diagnosed with anaphylaxis from bee and wasp venoms in need of rapid desensitization.

Mastocytosis demystified

Mastocytosis is a rare, clinically heterogenous clonal hematological neoplasm. Over 95% of patients harbor the driver KIT D816V mutation resulting in mast cell (MC) accumulation and proliferation in various organs, leading to variable symptom manifestations that result from MC mediator release in patients with systemic mastocytosis (SM) and end-organ damage in those with advanced SM. The accurate diagnostic and clinical classification of patients with SM is vital to underpin appropriate treatment options and personalize therapy. This review evaluates the current diagnostic criteria, clinical classification, risk stratification, and therapeutic options available for adult patients with nonadvanced and advanced SM.

Global Classification of Mast Cell Activation Disorders: An ICD-10-CM-Adjusted Proposal of the ECNM-AIM Consortium

Mast cell activation (MCA) is common and occurs in a number of pathologic conditions, including IgE-dependent and independent allergic reactions, atopic disorders, autoimmune processes, and mastocytosis. In a subset of patients, no underlying disease and no known trigger of MCA are found. When the symptoms are severe, systemic, and recurrent, and accompanied by a diagnostic increase in the serum tryptase level or other mast cell mediators, an MCA syndrome (MCAS) may be diagnosed. In these patients, the symptoms typically respond to drugs suppressing MCA, mediator production in mast cells, or mediator effects. In each case, diagnostic consensus criteria must be fulfilled to diagnose MCAS. In other patients, MCA may be local, less severe, or less acute, or may be suspected but not confirmed, so that the diagnostic criteria of MCAS are not fulfilled. In these patients, it may be difficult to prove MCA, for example, by measuring multiple mast cell mediators or basophil activation, the latter as a surrogate of IgE-dependent hypersensitivity. However, validated diagnostic criteria for implicating suspected MCA behind such conditions are lacking, even if some of these conditions have recently been assigned to an International Classification of Diseases-10-Clinical Modification code (ICD-10-CM). In this article, we discuss diagnostic features and criteria and propose a ICD-10-CM-adjusted classification for disorders associated with MCA, herein referred to as MCA disorders (MCADs), with special emphasis on the delineation between confirmed MCAS, MCAD not fulfilling MCAS criteria, and suspected MCAD that is not present. In addition, we discuss the discrimination between overt MCAD and predisposing conditions, such as atopic states, mastocytosis, and hereditary alpha tryptasemia.

Personalized Management Strategies in Mast Cell Disorders: ECNM-AIM User's Guide for Daily Clinical Practice

Mastocytosis is a myeloid neoplasm defined by expansion and focal accumulation of clonal mast cells (MCs) in one or more organs. The disease exhibits a complex pathology and may be complicated by MC activation, bone abnormalities, neurological problems, gastrointestinal symptoms, and/or hematologic progression. The World Health Organization divides mastocytosis into cutaneous forms, systemic mastocytosis (SM) and MC sarcoma. In most patients with SM, somatic mutations in KIT are detected. Patients with indolent SM have a normal to near-normal life expectancy, whereas patients with advanced SM, including aggressive SM and MC leukemia, have a poor prognosis. In those with advanced SM, multiple somatic mutations and an associated hematologic neoplasm may be detected. Mediator-related symptoms can occur in any type of mastocytosis. Symptoms may be mild, severe, or even life-threatening. In patients with severe acute symptoms, an MC activation syndrome may be diagnosed. In these patients, relevant comorbidities include IgE-dependent and IgE-independent allergies. Management of patients with SM is an emerging challenge in daily practice and requires in-depth knowledge and a multidisciplinary and personalized approach with selection of appropriate procedures and interventions. In this article, we review the current knowledge on SM and MC activation syndrome, with emphasis on multidisciplinary aspects in diagnosis and patient-specific management. In addition, we provide a user's guide for application of markers, algorithms, prognostic scores, and treatments for use in daily practice.

Updated Diagnostic Criteria and Classification of Mast Cell Disorders: A Consensus Proposal

Mastocytosis is a hematologic neoplasm characterized by expansion and focal accumulation of neoplastic mast cells (MC) in diverse organs, including the skin, bone marrow (BM), spleen, liver, and gastrointestinal tract. The World Health Organization classification divides the disease into prognostically distinct variants of cutaneous mastocytosis (CM) and systemic mastocytosis (SM). Although this classification remains valid, recent developments in the field and the advent of new diagnostic and prognostic parameters created a need to update and refine definitions and diagnostic criteria in MC neoplasms. In addition, MC activation syndromes (MCAS) and genetic features predisposing to SM and MCAS have been identified. To discuss these developments and refinements in the classification, we organized a Working Conference comprised of experts from Europe and the United States in August 2020. This article reports on outcomes from this conference. Of particular note, we propose adjustments in the classification of CM and SM, refinements in diagnostic criteria of SM variants, including smoldering SM and BM mastocytosis (BMM), and updated criteria for MCAS and other conditions involving MC. CD30 expression in MC now qualifies as a minor SM criterion, and BMM is now defined by SM criteria, absence of skin lesions and absence of B- and C-findings. A basal serum tryptase level exceeding 20 ng/mL remains a minor SM criterion, with recognition that hereditary alpha-tryptasemia and various myeloid neoplasms may also cause elevations in tryptase. Our updated proposal will support diagnostic evaluations and prognostication in daily practice and the conduct of clinical trials in MC disorders.

[Allergen immunotherapy: FAQs and facts]

Die Allergenimmuntherapie (AIT) ist – neben der oft nicht suffizient durchzuführenden Allergenmeidung – die einzige kausale Therapie Ig(Immunglobulin)E-vermittelter Allergien gegen Aeroallergene und Hymenopterengifte. Sie kann je nach Allergen als subkutane Injektion (subkutane Immuntherapie [SCIT]) oder über eine sublinguale Applikation (sublinguale Immuntherapie [SLIT]) erfolgen, kürzlich wurde zudem auch ein Verfahren zur oralen Immuntherapie zur Behandlung der Nahrungsmittelallergie zugelassen. Neben der korrekten Indikationsstellung (positive Anamnese und Diagnostik einer IgE-vermittelten Allergie, Allergenkarenz nicht ausreichend möglich) sind mögliche Kontraindikationen und Risikofaktoren zu beachten. Zudem kann es unter einer AIT zu – potenziell auch lebensgefährlichen – Nebenwirkungen kommen. Im Folgenden sollen häufig gestellte Fragen und Fakten zur Entscheidungsfindung für die Durchführung und zum Risikomanagement der AIT beleuchtet und unter Berücksichtigung der aktuellen Datenlage diskutiert werden.

Doctor, I Think I Am Suffering from MCAS: Differential Diagnosis and Separating Facts from Fiction

Mast cell activation syndrome (MCAS) is a rare condition defined by a severe systemic reaction to mast cell (MC)-derived mediators. Most cases present with clinical signs of anaphylaxis, and some have an underlying IgE-dependent allergy. A primary MC disease (mastocytosis) may also be detected. Severe recurrent MCAS episodes requiring intensive care or even resuscitation are typically found in patients who suffer from both mastocytosis and allergy against certain triggers, such as hymenoptera venom components. A less severe form and a local form of MC activation (MCA) also exist. For these patients, diagnostic criteria are lacking. Moreover, a number of different, unrelated, conditions with overlapping symptoms may be confused with MCAS. As a result, many patients believe that they are suffering from MCAS but have in fact a less severe form of MCA or another underlying disease. In the current article, we review the potential differential diagnoses of MCA and MCAS and discuss available diagnostic criteria and diagnostic tools. These criteria and assays may be useful in daily practice and help avoid unnecessary referrals and unjustified fears in patients.

EAACI Allergen Immunotherapy User's Guide

Allergen immunotherapy is a cornerstone in the treatment of allergic children. The clinical efficiency relies on a well-defined immunologic mechanism promoting regulatory T cells and downplaying the immune response induced by allergens. Clinical indications have been well documented for respiratory allergy in the presence of rhinitis and/or allergic asthma, to pollens and dust mites. Patients who have had an anaphylactic reaction to hymenoptera venom are also good candidates for allergen immunotherapy. Administration of allergen is currently mostly either by subcutaneous injections or by sublingual administration. Both methods have been extensively studied and have pros and cons. Specifically in children, the choice of the method of administration according to the patient's profile is important. Although allergen immunotherapy is widely used, there is a need for improvement. More particularly, biomarkers for prediction of the success of the treatments are needed. The strength and efficiency of the immune response may also be boosted by the use of better adjuvants. Finally, novel formulations might be more efficient and might improve the patient's adherence to the treatment. This user's guide reviews current knowledge and aims to provide clinical guidance to healthcare professionals taking care of children undergoing allergen immunotherapy.

Risk factors and indicators of severe systemic insect sting reactions

Hymenoptera venom allergy ranks among the top three causes of anaphylaxis worldwide, and approximately one-quarter of sting-induced reactions are classified as severe. Fatal sting reactions are exceedingly rare, but certain factors may entail a considerably higher risk. Delayed administration of epinephrine and upright posture are situational risk factors which may determine an unfavorable outcome of the acute anaphylactic episode and should be addressed during individual patient education. Systemic mastocytosis and senior age are major, unmodifiable long-term risk factors and thus reinforce the indication for venom immunotherapy. Vespid venom allergy and male sex likewise augment the risk of severe or even fatal reactions. Further studies are required to assess the impact of specific cardiovascular comorbidities. Available data regarding potential effects of beta-blockers and/or ACE inhibitors in coexisting venom allergy are inconclusive and do not justify recommendations to discontinue guideline-directed antihypertensive treatment. The absence of urticaria/angioedema during sting-induced anaphylaxis is indicative of a severe reaction, serum tryptase elevation, and mast cell clonality. Determination of basal serum tryptase levels is an established diagnostic tool for risk assessment in Hymenoptera venom-allergic patients. Measurement of platelet-activating factor acetylhydrolase activity represents a complementary approach but is not available for routine diagnostic use.

Sublingual immunotherapy of atopic dermatitis in mite-sensitized patients: a multi-centre, randomized, double-blind, placebo-controlled study

Allergen-specific immunotherapy is widely used for allergic rhinitis and asthma treatment worldwide. This study explored the efficacy and safety of sublingual immunotherapy (SLIT) with the extracts of Dermatophagoides Farinae (D. farinae Drops) on house dust mites (HDM)-induced atopic dermatitis (AD). 239 patients with HDM-induced AD were recruited and exposure to a multi-centre, randomized, double-blind, and placebo-controlled clinical trials for 36 weeks, which were randomly divided into placebo and sublingual D. farinae Drops groups (high-dose, medium-dose and low-dose), respectively. Statistical analysis was performed in three groups: Full Analysis Set, Per Protocol Set and Safety Set. 48 cases have withdrawn from the study before the end of study. As primary outcomes, significant decreases in scoring atopic dermatitis and total medication score were showed in medium-dose and high-dose D. farinae Drops groups. In the sixth visit, the skin lesion area showed a statistically significant difference between high-dose/medium-dose D. farinae Drops group and placebo group (p < .05). Most adverse events are slight, and no life-threatening adverse drug reaction happened. Our research demonstrates the beneficial effect of SLIT with high or medium dose D. farinae Drops on AD, and the treatment was well tolerated.

Venom immunotherapy in patients with clonal mast cell disorders: IgG4 correlates with protection

BACKGROUND

Patients with clonal mast cell disorders (cMCD), systemic mastocytosis (SM) and monoclonal mast cell activation syndrome (MMAS), represent an increased risk for Hymenoptera venom anaphylaxis (HVA). Lifelong venom immunotherapy (VIT) is recommended; however, its efficacy and safety are controversial. Hence, we sought to evaluate the efficacy and safety of VIT in HVA patients with cMCD.

METHODS

A retrospective study was conducted among 46 patients with Vespula venom allergy who had experienced severe HVA, 32 cMCD (22 with SM and 10 with MMAS) and 14 controls. There were no differences between cMCD patients and controls in age (58 vs 66) and duration of VIT (47 vs 48 months), respectively.

RESULTS

During VIT, 11 (34%) cMCD patients experienced adverse reactions (ARs) (7% in controls), including 1 anaphylaxis. There were 23 re-stings in 17 (53%) patients during VIT. Of episodes, four (17%) presented with anaphylaxis, 14 (60%) presented with local reaction, and five (23%) were asymptomatic. In 11 episodes (48%), the patient did not take epinephrine, of these 8 (73%) presented with local reaction, and 3 (27%) were asymptomatic. Patient-based protection from anaphylaxis was 76% (4/17) in cMCD vs. 100% in controls during VIT. The venom-specific IgG4 concentrations increased during VIT (P < .001) although tryptase and IgE were unaltered.

CONCLUSION

Both safety and efficacy of VIT in cMCD patients were slightly reduced than controls. Severe ARs were rare. The elevated IgG4 levels may be a biomarker for efficacy of VIT in cMCD patients, as it correlates with protection from re-stings.

The Role of KIT Mutations in Anaphylaxis

PURPOSE OF REVIEW

Gain of function KIT mutations are detected in clonal mast cell diseases, namely mastocytosis and monoclonal mast cell activation syndrome. Timely diagnosis and treatment of these disorders are crucial because of their association with severe and life-threatening anaphylaxis. KIT mutations also have implications for targeted therapies of mast cell disorders. This review article strives to serve as an overview of the role of clonal mast cell disorders in anaphylaxis while elucidating current and future therapies.

RECENT FINDINGS

Clonal mast cell disease has been increasingly diagnosed in patients with severe hymenoptera allergy and those with recurrent unexplained anaphylaxis. The current state of knowledge of the epidemiology, pathophysiology, diagnosis, and treatment of mastocytosis with a particular focus on anaphylaxis and its triggers which are described in this context. Novel and forthcoming treatments are discussed including the relevance of KIT mutation status. This review provides an overview of the role of KIT mutations in mastocytosis and anaphylaxis, and highlights emerging therapies for mastocytosis, targeting these mutations.

Adverse reactions to drugs and biologics in patients with clonal mast cell disorders: A Work Group Report of the Mast Cells Disorder Committee, American Academy of Allergy, Asthma & Immunology

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.

EAACI guidelines on allergen immunotherapy: Hymenoptera venom allergy

Hymenoptera venom allergy is a potentially life-threatening allergic reaction following a honeybee, vespid, or ant sting. Systemic-allergic sting reactions have been reported in up to 7.5% of adults and up to 3.4% of children. They can be mild and restricted to the skin or moderate to severe with a risk of life-threatening anaphylaxis. Patients should carry an emergency kit containing an adrenaline autoinjector, H₁ -antihistamines, and corticosteroids depending on the severity of their previous sting reaction(s). The only treatment to prevent further systemic sting reactions is venom immunotherapy. This guideline has been prepared by the European Academy of Allergy and Clinical Immunology's (EAACI) Taskforce on Venom Immunotherapy as part of the EAACI Guidelines on Allergen Immunotherapy initiative. The guideline aims to provide evidence-based recommendations for the use of venom immunotherapy, has been informed by a formal systematic review and meta-analysis and produced using the Appraisal of Guidelines for Research and Evaluation (AGREE II) approach. The process included representation from a range of stakeholders. Venom immunotherapy is indicated in venom-allergic children and adults to prevent further moderate-to-severe systemic sting reactions. Venom immunotherapy is also recommended in adults with only generalized skin reactions as it results in significant improvements in quality of life compared to carrying an adrenaline autoinjector. This guideline aims to give practical advice on performing venom immunotherapy. Key sections cover general considerations before initiating venom immunotherapy, evidence-based clinical recommendations, risk factors for adverse events and for relapse of systemic sting reaction, and a summary of gaps in the evidence.

Venom immunotherapy in patients with allergic reactions to insect stings

INTRODUCTION

Allergy to Hymenoptera (Apis mellifera, Vespula species, Polistes species, Vespa crabro) venom can be safely and effectively treated by venom immunotherapy (VIT), which in the 40 years since its introduction has been able to prevent reactions to stings, and to treatment as well, though systemic reactions, occasionally severe, are possible. Areas covered: We reviewed the recent literature on VIT by searching in PubMed for the terms 'venom immunotherapy' and 'Hymenoptera venom immunotherapy' to highlight the current status of VIT and the likely development in the coming years. Expert commentary: VIT, provided the correct choice of the venom and adequate venom preparations and maintenance doses are used, is a treatment of great value in preventing systemic reactions to Hymenoptera stings. A 5-year duration ensures a prolonged tolerance to stings following VIT discontinuation, unless patients suffer from mastocytosis. In fact, due to reports of fatal reactions after stopping VIT, patients with mastocytosis, or with very severe reactions to stings, need an indefinite duration of treatment.

Advances in the understanding and clinical management of mastocytosis and clonal mast cell activation syndromes

Clonal mast cell activation syndromes and indolent systemic mastocytosis without skin involvement are two emerging entities that sometimes might be clinically difficult to distinguish, and they involve a great challenge for the physician from both a diagnostic and a therapeutic point of view. Furthermore, final diagnosis of both entities requires a bone marrow study; it is recommended that this be done in reference centers. In this article, we address the current consensus and guidelines for the suspicion, diagnosis, classification, treatment, and management of these two entities.

Added sensitivity of component-resolved diagnosis in hymenoptera venom-allergic patients with elevated serum tryptase and/or mastocytosis

BACKGROUND

Anaphylaxis caused by hymenoptera venom allergy is associated with elevation of baseline serum tryptase (sBT) and/or mastocytosis in about 5% of patients. Up to now, no information has become available on single venom allergen sIgE reactivity and the usefulness of component-resolved approaches to diagnose this high-risk patient group. To address the component-resolved sIgE sensitization pattern and diagnostic sensitivity in hymenoptera venom-allergic patients with elevated sBT levels and/or mastocytosis, a panel of yellow jacket and honeybee venom allergens was applied on a widely used IgE immunoassay platform.

METHODS

Fifty-three patients with mastocytosis and/or elevated sBT tryptase level and systemic reactions to hymenoptera venoms were analyzed for their IgE reactivity to recombinant yellow jacket and honeybee venom allergens by Immulite3 g.

RESULTS

sIgE reactivity to Ves v 1, Ves v 5, Api m 1 to Api m 4 and Api m 10 was found at a similar frequency in hymenoptera venom-allergic patients with and without elevated sBT levels and/or mastocytosis. However, the use of the recombinant allergens and a diagnostic cutoff of 0.1 kUA /L allowed the diagnosis of patients with otherwise undetectable IgE to venom extract. The diagnostic sensitivity of yellow jacket venom allergy using the combination of Ves v 1 and Ves v 5 was 100%.

CONCLUSIONS

In high-risk patients with elevated sBT levels and/or mastocytosis, the use of molecular components and decreasing the threshold sIgE level to 0.1 kUA /L may be needed to avoid otherwise undetectable IgE to hymenoptera venom extracts in about 8% of such patients.

Hymenoptera Allergy and Mast Cell Activation Syndromes

Mast cell activation syndrome (MCAS) can be diagnosed in patients with recurrent, severe symptoms from mast cell (MC)-derived mediators, which are transiently increased in serum and are attenuated by mediator-targeting drugs. When KIT-mutated, clonal MC are detected in these patients, a diagnosis of primary MCAS can be made. Severe systemic reactions to hymenoptera venom (HV) represent the most common form of anaphylaxis in patients with mastocytosis. Patients with primary MCAS and HV anaphylaxis are predominantly males and do not have skin lesions in the majority of cases, and anaphylaxis is characterized by hypotension and syncope in the absence of urticaria and angioedema. A normal value of tryptase (≤11.4 ng/ml) in these patients does not exclude a diagnosis of mastocytosis. Patients with primary MCAS and HV anaphylaxis have to undergo lifelong venom immunotherapy, in order to prevent further potentially fatal severe reactions.

Risk associated with bee venom therapy: a systematic review and meta-analysis

OBJECTIVE

The safety of bee venom as a therapeutic compound has been extensively studied, resulting in the identification of potential adverse events, which range from trivial skin reactions that usually resolve over several days to life-threating severe immunological responses such as anaphylaxis. In this systematic review, we provide a summary of the types and prevalence of adverse events associated with bee venom therapy.

METHODS

We searched the literature using 12 databases from their inception to June 2014, without language restrictions. We included all types of clinical studies in which bee venom was used as a key intervention and adverse events that may have been causally related to bee venom therapy were reported.

RESULTS

A total of 145 studies, including 20 randomized controlled trials, 79 audits and cohort studies, 33 single-case studies, and 13 case series, were evaluated in this review. The median frequency of patients who experienced adverse events related to venom immunotherapy was 28.87% (interquartile range, 14.57-39.74) in the audit studies. Compared with normal saline injection, bee venom acupuncture showed a 261% increased relative risk for the occurrence of adverse events (relative risk, 3.61; 95% confidence interval, 2.10 to 6.20) in the randomized controlled trials, which might be overestimated or underestimated owing to the poor reporting quality of the included studies.

CONCLUSIONS

Adverse events related to bee venom therapy are frequent; therefore, practitioners of bee venom therapy should be cautious when applying it in daily clinical practice, and the practitioner's education and qualifications regarding the use of bee venom therapy should be ensured.

Anaphylaxis as a clinical manifestation of clonal mast cell disorders

Clonal mast cell disorders comprise a heterogeneous group of disorders characterized by the presence of gain of function KIT mutations and a constitutively altered activation-associated mast cell immunophenotype frequently associated with clinical manifestations related to the release of mast cells mediators. These disorders do not always fulfil the World Health Organization (WHO)-proposed criteria for mastocytosis, particularly when low-sensitive diagnostic approaches are performed. Anaphylaxis is a frequent presentation of clonal mast cell disorders, particularly in mastocytosis patients without typical skin lesions. The presence of cardiovascular symptoms, e.g., hypotension, occurring after a hymenoptera sting or spontaneously in the absence of cutaneous manifestations such as urticaria is characteristic and differs from the presentation of anaphylaxis in the general population without mastocytosis.

Nonaggressive systemic mastocytosis (SM) without skin lesions associated with insect-induced anaphylaxis shows unique features versus other indolent SM

BACKGROUND

Indolent systemic mastocytosis (ISM) without skin lesions (ISMs(-)) shows a higher prevalence in males, lower serum baseline tryptase levels, and KIT mutation more frequently restricted to bone marrow (BM) mast cells (MCs) than ISM with skin lesions (ISMs(+)). Interestingly, in almost one-half of ISMs(-) patients, MC-mediator release episodes are triggered exclusively by insects.

OBJECTIVE

We aimed to determine the clinical and laboratory features of ISMs(-) associated with insect-induced anaphylaxis (insectISMs(-)) versus other patients with ISM.

METHODS

A total of 335 patients presenting with MC activation syndrome, including 143 insectISMs(-), 72 ISMs(-) triggered by other factors (otherISMs(-)), 56 ISMs(+), and 64 nonclonal MC activation syndrome, were studied.

RESULTS

Compared with otherISMs(-) and ISMs(+) patients, insectISMs(-) cases showed marked male predominance (78% vs 53% and 46%; P < .001), a distinct pattern of MC-related symptoms, and significantly lower median serum baseline tryptase levels (22.4 vs 28.7 and 45.8 μg/L; P ≤ .009). Moreover, insectISMs(-) less frequently presented BM MC aggregates (46% vs 70% and 81%; P ≤ .001), and they systematically showed MC-restricted KIT mutation.

CONCLUSIONS

ISMs(-) patients with anaphylaxis triggered exclusively by insects display clinical and laboratory features that are significantly different from other ISM cases, including other ISMs(-) and ISMs(+) patients, suggesting that they represent a unique subgroup of ISM with a particularly low BM MC burden in the absence of adverse prognostic factors.

Management of insect sting hypersensitivity: an update

Reactions to Hymenoptera insect stings are common. While most are self-limited, some induce systemic allergic reactions or anaphylaxis. Prompt recognition, diagnosis, and treatment of these reactions are important for improving quality-of-life and reducing the risk of future sting reactions. This review summarizes the current recommendations to diagnose and treat Hymenoptera sting induced allergic reactions and highlights considerations for various populations throughout the world.

Efficacy of venom immunotherapy given every 3 or 4 months: a prospective comparison with the conventional regimen

BACKGROUND

Standard venom immunotherapy involves the administration of the maintenance dose every 4 to 6 weeks. This regimen may have adherence problems, especially in the long term; thus, extended intervals have been proposed.

OBJECTIVE

We prospectively compared the efficacy of 3- or 4-month extended maintenance dose vs the conventional regimen.

METHODS

Patients receiving immunotherapy with a single venom were offered the extended maintenance dose (EMD) and were then followed up for field re-stings. Only the re-stings by the insect for which the patients received immunotherapy were considered. A comparable group of patients receiving the conventional maintenance dose (CMD) was used for comparison by logistic regression analysis.

RESULTS

Seventy-six patients (60 male; mean age, 48 years) receiving the EMD were re-stung on 247 occasions by the insect for which they were receiving immunotherapy. The group receiving CMD included 110 patients (82 male; mean age, 44 years) certainly re-stung on 167 occasions by the specific insect. The percentage of re-sting without reaction was 93.5% in the EMD group and 81.5% in the CMD group, with a significant difference in favor of the former (P=.001). At logistic regression analysis, only age, but not maintenance dose protocol, was predictive of subsequent systemic reactions.

CONCLUSION

The EMD is as effective and safe as the CMD. An increased maintenance seems to be the best option in term of convenience and economic savings.

The role of basophil activation test in special populations with mastocytosis and reactions to hymenoptera sting

BACKGROUND

Systemic mastocytosis (SM) may be associated with hymenoptera allergy. In such cases, immunotherapy is a life-saving treatment, but a circumstantiated diagnosis is needed for its prescription. Patients with SM and previous reactions to stings, but with negative tests represent a diagnostic dilemma. The basophil activation test (BAT) may be helpful in refining the diagnosis.

OBJECTIVE

We assessed the usefulness of BAT in subpopulations of mastocytosis patients, including those with negative tests for insect allergy.

METHODS

Within a population of patients with mastocytosis and previous stings, we studied by BAT and augmented intradermal test (IDT) (10 µg/ml) two groups: (1) with reactions to stings and negative tests; (2) without reactions and negative tests. Basophil activation test was performed with different venoms, assessing at flow cytometry basophils' activation.

RESULTS

Sixty-three patients had mastocytosis and 52 had reactions to previous hymenoptera stings. Of them, seven proved negative to diagnostic tests. In six of seven of those patients, BAT was negative with all venoms, and in one, basophils resulted activated also with the negative control. In six patients without previous reactions and negative tests, BAT was totally negative in five of six patients and weakly positive to Hornet in one. Finally, the IDT at 10 µg/ml venom produced nonspecific positive results in most cases.

CONCLUSION

In patients with mastocytosis, the negative results of standard tests are reliable, because BAT and IDT at higher concentration do not add useful information.

Venom immunotherapy in patients with mastocytosis and hymenoptera venom anaphylaxis

Systemic mastocytosis (SM) is typically suspected in patients with cutaneous mastocytosis (CM). In recent years, the presence of clonal mast cells (MCs) in a subset of patients with systemic symptoms associated with MC activation in the absence of CM has been reported and termed monoclonal MC activation syndromes or clonal systemic MC activation syndromes. In these cases, bone marrow (BM) MC numbers are usually lower than in SM with CM, there are no detectable BM MC aggregates, and serum baseline tryptase is often <20 µg/l; thus, diagnosis of SM in these patients should be based on careful evaluation of other minor WHO criteria for SM in reference centers, where highly sensitive techniques for immunophenotypic analysis and investigation of KIT mutations on fluorescence-activated cell sorter-purified BM MCs are routinely performed. The prevalence of hymenoptera venom anaphylaxis (HVA) among SM patients is higher than among the normal population and it has been reported to be approximately 5%. In SM patients with IgE-mediated HVA, venom immunotherapy is safe and effective and it should be prescribed lifelong. Severe adverse reactions to hymenoptera stings or venom immunotherapy have been associated with increased serum baseline tryptase; however, presence of clonal MC has not been ruled out in most reports and thus both SM and clonal MC activation syndrome might be underdiagnosed in such patients. In fact, clonal BM MC appears to be a relevant risk factor for both HVA and severe reactions to venom immunotherapy, while the increase in serum baseline tryptase by itself should be considered as a powerful surrogate marker for anaphylaxis. The Spanish Network on Mastocytosis has developed a scoring system based on patient gender, the clinical symptoms observed during anaphylaxis and serum baseline tryptase to predict for the presence of both MC clonality and SM among individuals who suffer from anaphylaxis.

Clinical immunology review series: an approach to desensitization

Allergen immunotherapy describes the treatment of allergic disease through administration of gradually increasing doses of allergen. This form of immune tolerance induction is now safer, more reliably efficacious and better understood than when it was first formally described in 1911. In this paper the authors aim to summarize the current state of the art in immunotherapy in the treatment of inhalant, venom and drug allergies, with specific reference to its practice in the United Kingdom. A practical approach has been taken, with reference to current evidence and guidelines, including illustrative protocols and vaccine schedules. A number of novel approaches and techniques are likely to change considerably the way in which we select and treat allergy patients in the coming decade, and these advances are previewed.

Mastocytosis and insect venom allergy: diagnosis, safety and efficacy of venom immunotherapy

The most important causative factor for anaphylaxis in mastocytosis are insect stings. The purpose of this review is to analyse the available data concerning prevalence, diagnosis, safety and effectiveness of venom immunotherapy (VIT) in mastocytosis patients. If data were unclear, authors were contacted personally for further information. Quality of evidence (A: high, B: moderate, C: low and D: very low) and strength of recommendation (strong 1 and weak 2) concerning VIT in mastocytosis patients are assessed according to the Grading of Recommendations Assessment, Development and Evaluation and are marked in square brackets. Results of VIT were described in 117 patients to date. The mean rate of side-effects during treatment in studies published so far is 23.9% (7.6% requiring adrenaline) with an overall protection rate of 72%. Based on the review we conclude that (1) mastocytosis patients have a high risk of severe sting reactions in particular to yellow jacket, (2) VIT could be suggested [2] in mastocytosis, (3) probably should be done life long [2], (4) VIT in mastocytosis is accompanied by a higher frequency of side-effects, so (5) special precautions should be taken into account notably during the built up phase of the therapy [2], (6) VIT is able to reduce systemic reactions, but to a lesser extent compared to the general insect venom allergic population [2], so (7) patients should be warned that the efficacy of VIT might be less than optimal and they should continue carrying two adrenaline auto injectors [2].

The problem of anaphylaxis and mastocytosis

Mastocytosis is a rare disease characterized by an elevated whole body mast cell number. Anaphylaxis is a severe, generalized hypersensitivity reaction with rapid onset. The problem of anaphylaxis and mastocytosis is due to strongly increased mediator release from the elevated mast cell number during allergic reactions. This explains the much higher prevalence of anaphylaxis in mastocytosis than in the general population and its severe and sometimes fatal course. Because of the increased risk of anaphylaxis in mastocytosis, all patients with severe or recurrent anaphylaxis should be analyzed for underlying mastocytosis by estimation of baseline serum tryptase. If this is elevated, patients also should be tested via skin examination for cutaneous mastocytosis and with a bone marrow biopsy. All patients with mastocytosis and anaphylaxis must be instructed about avoiding the responsible elicitors and should carry an emergency kit with adrenaline for self-application. In mastocytosis patients with anaphylaxis due to Hymenoptera stings, venom immunotherapy is recommended for life.

Issues in stinging insect allergy immunotherapy: a review

PURPOSE OF REVIEW

The treatment of insect allergy by desensitization still continues to present with some unanswered questions. This review will focus mainly on articles that have dealt with these issues in the past 2 years.

RECENT FINDINGS

With the publication in 2007 of Allergen Immunotherapy: a practice parameter second update, many of the key issues were reviewed and summarized. Other recent studies deal with omalizumab pretreatment of patients with systemic mastocytosis and very severe allergic reactions to immunotherapy. It would appear that venom immunotherapy is somewhat unique compared to inhalant allergen immunotherapy in that premedication prior to rush protocols may not be necessary and that intervals of therapy may be longer than with allergen immunotherapy. The use of concomitant medications such as beta-blockers may be indicated in special situations. Angiotensin-converting enzyme inhibitors can be stopped temporarily before venom injections to prevent reactions. The issue of when to discontinue immunotherapy remains unsettled and should be individualized to patient requirements.

SUMMARY

The newest revision of the Immunotherapy Parameters provides much needed information concerning successful treatment with immunotherapy of Hymenoptera-sensitive patients.

Practice of venom immunotherapy in the United Kingdom: a national audit and review of literature

BACKGROUND

Venom immunotherapy (VIT) is the only effective treatment for prevention of serious allergic reactions to bee and wasp stings in sensitized individuals. However, controversies exist relating to diagnosis, indications for treatment and treatment schedules. We audited current practice of VIT in the United Kingdom to evaluate adherence to international guidelines.

METHODS

An online questionnaire was sent to all clinicians practising immunotherapy identified on the British Society of Allergy and Clinical Immunology website. Eighty-six questionnaires were sent and 53 responses (61.6%) were received. Of these, 48 (85%) carried out VIT at their centre.

RESULTS

Skin prick tests (SPT) and serum venom-specific IgE (SSIgE) were equally preferred as first-line investigation. Fifty percent of the respondents perform intradermal tests if both SPT and SSIgE are negative. While 8% of respondents commence VIT in patients with negative SSIgE and a history of severe reaction, 57% prefer to repeat the tests in 6-12 months if serum tryptase is elevated. If the insect responsible is uncertain and SSIgE is detected against bee and wasp venoms, 22% of the respondents will desensitize to both while 32% initiate treatment against the venom with the higher SSIgE. A protocol of weekly up-dosing for 12 weeks is preferred for induction and only 25% of respondents have ever used rush or ultra-rush protocols. Three years is thought to be optimum duration of VIT by most (56%). Eleven percent perform sting challenges at the end of treatment. Although 47% measure SSIgE at the end of treatment, only 3% use these results as a basis for discontinuing VIT.

CONCLUSION

Currently there is considerable variation in the diagnosis and management of hymenoptera venom allergy in the United Kingdom. This audit has demonstrated that the current international guidelines for the diagnosis and management of hymenoptera venom allergy are not being followed by UK allergy practitioners.