Anaphylaxis caused by Hymenoptera stings: from epidemiology to treatment

Basophil activation test in the diagnosis and monitoring of mastocytosis patients with wasp venom allergy on immunotherapy

BACKGROUND

There is need for an accurate diagnostic test in mastocytosis patients with wasp venom allergy (WVA) and monitoring of these patients during immunotherapy (IT). In this study, we aimed to evaluate sensitivity and specificity of the Basophil Activation Test (BAT) as a diagnostic and monitoring test in patients with mastocytosis and WVA.

METHODS

Seventeen patients with mastocytosis and WVA and six mastocytosis patients without WVA were included. BAT was performed before the start of IT (first visit) and at 6 weeks (second visit) and 1 year (third visit), after reaching the maintenance dose. Of 17 patients included, 11 completed the third visit. In mastocytosis patients with WVA, dose-dependent wasp-venom induced upregulation of CD63 and CD203c expression on basophils was observed compared with mastocytosis patients without WVA. Serum specific IgE, IgG4, and tryptase levels were measured in all patients.

RESULTS

BAT had a sensitivity of 87% and specificity of 100% in diagnosing WVA in mastocytosis patients. Basophil allergen threshold sensitivity with respect to CD63 and CD203c was significantly decreased in the second visit compared with the first visit and increased significantly in the third visit compared with the second visit. Specific IgE levels increased significantly in the second visit compared with first and decreased significantly in the third visit compared with the second. Specific IgG4 levels rose significantly in the second visit compared with the first and on the third visit compared with the second. Tryptase levels did not change significantly during the study.

CONCLUSIONS

BAT represents a diagnostic test with 100% specificity in allergic patients with mastocytosis and these patients are better to be monitored for a longer period during IT.

An update on venom allergy

PURPOSE OF REVIEW

Allergic reactions to stinging insects may be unexpected, frightening, and severe. A clear understanding of recent advances in the field facilitates appropriate care of children who experience severe reactions to hymenoptera stings.

RECENT FINDINGS

Recent investigations have underscored the importance of appropriate patient selection for potentially life-saving venom immunotherapy. Venom immunotherapy is effective in preventing future anaphylaxis from hymenoptera stings. Immunotherapy is indicated for patients with a history of anaphylaxis. Children who develop large local swelling or strictly cutaneous systemic reactions generally do not require immunotherapy. Component resolved diagnostic testing has been investigated to clarify the possibility of multiple venom allergies in patients with sensitization to multiple venoms.

SUMMARY

Rapid recognition and treatment of anaphylaxis are critical. Subsequent education about avoiding future stings and attention to emergency preparedness with appropriate prescription of self-injectable epinephrine is important. Referral of patients who have experienced venom-associated anaphylaxis for possible venom immunotherapy can prevent future severe episodes of anaphylaxis resulting from stings.

Bites and stings: epidemiology and treatment

Rapid and effective treatment of bites is a major variable in the overall outcome of a patient who is a victim of a bite. There are a wide range of animals that bite and sting, and the reactions vary depending on the individual and the animal involved. Although most bites are treated on an outpatient basis, patients who have severe complications related to bites become patients in critical care settings. An overview of potential bite and sting sources, with some general guidelines for what to expect and how to treat the patient, is presented.

Short-term venom immunotherapy induces desensitization of FcεRI-mediated basophil response

BACKGROUND

The precise immunological mechanisms for the early clinical protection of venom immunotherapy (VIT) have not yet been explained. Our aim was to evaluate whether high-affinity IgE receptor (FcεRI) and the related basophil function have a role in the induction of short-term VIT protection.

METHODS

We included 60 adults and 48 children. Basophil threshold sensitivity (CD-sens) to anti-FcεRI stimulation, and FcεRI gene and cell-surface expression were assessed at the beginning and just before the first maintenance dose (MD) of 100 μg of ultra-rush VIT (day 5) and at the beginning, during buildup, and just before the first MD of 70 μg and of 100 μg of semi-rush VIT (weeks 1-2 and 5).

RESULTS

We demonstrated a significant reduction in CD-sens to anti-FcεRI stimulation before the first MD in both ultra-rush and semi-rush VIT in all included subjects. FcεRI gene and/or cell-surface expression was decreased in 34-100% of subjects, with different dynamics between VIT protocols.

CONCLUSION

We found a marked desensitization of FcεRI-activated basophils after short-term VIT. This suppression, which could be highly relevant for the development of early protective mechanisms, might be also related to the changes at the level of FcεRI expression.

Anaphylaxis in an emergency setting - elicitors, therapy and incidence of severe allergic reactions

BACKGROUND

Anaphylaxis is a severe potentially life-threatening hypersensitivity reaction with an estimated lifetime prevalence of 0.5-2.0%. The prevalence and incidence of anaphylactic reactions in Germany are unknown. We therefore assessed anaphylactic patients seen by emergency physicians in the Berlin area covering 4 million people.

METHODS

A standardised questionnaire was filled from 2008 to 2010 by the emergency physicians.

RESULTS

A total of 333 cases of anaphylaxis were reported. 295 of these met the inclusion criteria for severity and were analysed. 13.9% (n = 41) were reactions with respiratory symptoms, 25.4% (n = 75) with cardiovascular, and in 60.7% (n = 179) of cases, respiratory and cardiovascular symptoms were reported. Two reactions were fatal. The most common elicitors were food products (32.2%), drugs (29.2%) and insect venom (19.3%). The most frequently given drugs were corticoids and antihistamines, but not adrenaline. For 2008, the calculated incidence was 4.5 per 100 000.

CONCLUSIONS

Our data show that food products are frequent elicitors of severe allergic reactions in the general population including children and adults. It unravels a strong underuse of adrenaline by emergency physicians, not reflecting treatment protocols according to the current guidelines. As data obtained from allergists reveal a different rank order of elicitors, this study suggests that food-allergic adult patients may present a risk population and should receive more attention by allergists.

2012 Update: World Allergy Organization Guidelines for the assessment and management of anaphylaxis

PURPOSE OF REVIEW

The World Allergy Organization (WAO) Guidelines for the assessment and management of anaphylaxis published in early 2011 provide a global perspective on patient risk factors, triggers, clinical diagnosis, treatment, and prevention of anaphylaxis. In this 2012 Update, subsequently published, clinically relevant research in these areas is reviewed.

RECENT FINDINGS

Patient risk factors and co-factors that amplify anaphylaxis have been documented in prospective studies. The global perspective on the triggers of anaphylaxis has expanded. The clinical criteria for the diagnosis of anaphylaxis that are promulgated in the Guidelines have been validated. Some aspects of anaphylaxis treatment have been prospectively studied. Novel investigations of self-injectable epinephrine for treatment of anaphylaxis recurrences in the community have been performed. Progress has been made with regard to measurement of specific IgE to allergen components (component-resolved testing) that might help to distinguish clinical risk of future anaphylactic episodes to an allergen from asymptomatic sensitization to the allergen. New strategies for immune modulation to prevent food-induced anaphylaxis and new insights into subcutaneous immunotherapy to prevent venom-induced anaphylaxis have been described.

SUMMARY

Research highlighted in this Update strengthens the evidence-based recommendations for assessment, management, and prevention of anaphylaxis made in the WAO Anaphylaxis Guidelines.

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.

IgE to recombinant allergens Api m 1, Ves v 1, and Ves v 5 distinguish double sensitization from crossreaction in venom allergy

BACKGROUND

Diagnostic tests in patients with Hymenoptera venom allergy are frequently positive to venoms of both honey bee and wasp (Vespula). Component-resolved analysis with recombinant species-specific major allergens (rSSMA) may help to distinguish true double sensitization from crossreactivity.

METHODS

Included were 121 patients with systemic allergic reactions to Hymenoptera stings, 76 with double positivity of serum-specific IgE (sIgE) to both venoms, 45 with single positivity to bee or wasp venom, and 32 controls without history of systemic reactions to Hymenoptera stings and no sIgE to whole venoms. In venom-allergic patients and controls, sIgE to rSSMA Api m 1 of bee venom and to Ves v 1 and Ves v 5 of wasp venom were tested by ImmunoCAP.

RESULTS

Only 47% of 76 patients with double positivity to whole venoms reacted also to rSSMA of both species. Specificity of sIgE to the 3 rSSMA was very high, with no sIgE to rSSMA of the other species in single-positive venom-allergic patients and only one control with low sIgE to Ves v 1. All wasp-allergic single-positive patients had sIgE to Ves v 5 and/or Ves v 1, and 78.3% of single-positive bee venom-allergic patients had sIgE to Api m 1.

CONCLUSION

Specificity of sIgE to rSSMA of both species is excellent. Sensitivity of sIgE to rSSMA was optimal for wasp venom. Sensitivity of bee venom Api m 1 could be increased by adding rSSMA of other important bee venom allergens.