Hyposensitisation to wasp venom in six hours

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.

Clinical Utility of Rush Venom Immunotherapy: Current Status

Hymenoptera venom allergy (HVA) is the leading cause of anaphylactic reactions in adults and the second most common cause in children. Venom immunotherapy (VIT) is used to elicit an immune tolerance against hymenoptera venom in allergic patients and is based on the administration of purified venom extracts regularly for defined periods. The protocols of administration include 2 phases: an up-dosing phase that incrementally reaches the final dose resulting in a protective effect, and a maintenance phase in order to obtain the sustained effect. The goal of this review is to detail the efficacy and the safety of the up-dosing phase also named rush. Pathophysiological mechanisms, indications of VIT and technical aspects of up-dosing protocol are also covered.

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.

Early suppression of basophil activation during allergen-specific immunotherapy by histamine receptor 2

BACKGROUND

Early desensitization of FcεRI-bearing mast cells and basophils has been demonstrated in allergen-specific immunotherapy and drug desensitization. However, its mechanisms have not been elucidated in detail. Histamine is one of the main mediators released on FcεRI triggering of basophils and mast cells, and it exerts its functions through histamine receptors (HRs).

OBJECTIVES

We sought to investigate HR expression on basophils of patients undergoing venom immunotherapy (VIT) and its effect on allergen, IgE, and FcεRI cross-linking-mediated basophil function and mediator release.

METHODS

Basophils were purified from the peripheral blood of patients undergoing VIT and control subjects and were studied functionally by using real-time PCR, flow cytometry and ELISA assays.

RESULTS

Rapid upregulation of H2R within the first 6 hours of the build-up phase of VIT was observed. H2R strongly suppressed FcεRI-induced activation and mediator release of basophils, including histamine and sulfidoleukotrienes, as well as cytokine production in vitro.

CONCLUSION

Immunosilencing of FcεRI-activated basophils by means of selective suppression mediated by H2R might be highly relevant for the very early induction of allergen tolerance and the so-called desensitization effect of VIT.

Hymenoptera Venom Immunotherapy: Tolerance and Efficacy of an Ultrarush Protocol versus a Rush and a Slow Conventional Protocol

Background and Objective. Various venom immunotherapy (VIT) protocols are available for Hymenoptera allergy. Although adverse reactions (ADRs) to VIT are widely reported, controlled trials are still needed. We conducted a randomized prospective study to evaluate ADRs and the efficacy of three VIT regimens. Methods. 76 patients with Hymenoptera allergy, aged 16-76 years, were randomized to receive an ultrarush protocol (group A: 27 patients), a rush protocol (group B: 25), or a slow protocol (group C: 24). Aqueous venom extract was used in incremental phase and an adsorbed depot in maintenance phase. ADRs and accidental Hymenoptera stings during VIT were used to evaluate efficacy. Results. During incremental treatment, ADRs occurred in 1.99%, 3.7%, and 3.9% of patients in groups A, B, and C, and in 0.99%, 1.46%, and 2.7%, respectively, during maintenance. ADRs were significantly fewer in group A (incremental + maintenance phase) than in group C (1.29% versus 3.2%; P = 0.013). Reactions to accidental Hymenoptera stings did not differ among groups (1.1%, 1.2%, and 1.1%). Conclusion. Ultrarush was as effective as the rush and slow protocols and was associated with a low incidence of reactions to stings. This study indicates that ultrarush VIT is a valid therapeutic option for Hymenoptera allergy.

Induction of specific immunotherapy with hymenoptera venoms using ultrarush regimen in children: safety and tolerance

Background & Objective. Ultrarush induction for specific venom immunotherapy has been shown to be reliable and efficacious in adults. In this study its safety and tolerance in children was evaluated. Methods. Retrospective analysis of 102 ultrarush desensitizations carried out between 1997 and 2005 in 94 children, aged 4 to 15 years. Diagnosis and selection for immunotherapy were according to recommendations of the European Academy of Allergy and Clinical Immunology. Systemic adverse reactions (SARs) were described using the classification of H. L. Mueller. Results. All patients reached the cumulative dose of 111.1 μg hymenoptera venom within 210 minutes. Six patients (6%) had allergic reactions grade I; 2 patients (2%) grade II and 5 patients (5%) grade III. Three patients (3%) showed unclassified reactions. SARs did not occur in the 15 patients aged 4 to 8 years and they were significantly more frequent in girls (29%) compared with boys (12%) (P = 0.034, multivariant analysis) and in bee venom extract treated patients (20%) compared to those treated with wasp venom extract (8%) (OR 0.33, 95% Cl 0.07-1.25). Conclusion. Initiation of specific immunotherapy by ultrarush regimen is safe and well tolerated in children and should be considered for treating children with allergy to hymenoptera venom.

Changes in intracellular cyclic adenosine monophosphate levels in peripheral blood leukocytes during immunotherapy with vespid venom

BACKGROUND

The allergen-induced release of mediators from basophils is known to be decreased after rush venom immunotherapy (VIT) compared with pretreatment values. A rise in the intracellular cyclic adenosine monophosphate (cAMP) level is known to inhibit mediator release.

OBJECTIVES

To determine changes in cAMP levels in peripheral blood leukocytes (PBLs) during rush VIT and to evaluate their relation to allergen-specific reactivity of basophils.

METHODS

Ten patients allergic to vespid venom (VV) were investigated before rush VIT and after reaching the maintenance dose. Five VV-allergic patients not undergoing VIT served as controls. Patients' PBLs were incubated with VV, and allergen-induced histamine and leukotriene release from basophils was measured. Levels of cAMP were determined in PBLs and in plasma.

RESULTS

Immediately after rush VIT, VV-induced histamine release (P = .04) and VV-induced leukotriene release (P = .01) were significantly reduced. Intracellular cAMP levels increased significantly (P = .047). However, 6 months after VIT, mediator responses in basophils were comparable with pre-VIT values. No significant changes were found in the control group.

CONCLUSIONS

An increase in intracellular cAMP levels might account for the decreased reactivity of basophils to allergen after 1 week of VIT. However, similar to the decreased mediator release after 1 week of VIT, this is not a long-term effect as values returned to baseline after 6 months.

IgE-mediated allergen presentation and blocking antibodies: regulation of T-cell activation in allergy

It is well established that both the production of IgE by B lymphocytes and the maturation and recruitment of eosinophils in late-phase reactions are dependent on the activation of allergen-specific type-2 T-helper cells. What is less well known is the fact that efficient activation of allergen-specific T cells upon low-dose exposure to allergens is critically dependent on IgE-mediated or -facilitated allergen presentation. In fact, changes in the level of IgE-mediated allergen presentation may account for many of the immunological effects described for specific immunotherapy or anti-IgE treatment. This review aims to summarize the current knowledge, and will discuss the clinical relevance of blocking IgG antibodies induced by specific immunotherapy and anti-IgE monoclonal antibodies that both interfere with IgE-mediated allergen presentation.

Prevention and treatment of hymenoptera venom allergy: guidelines for clinical practice

Based on the knowledge of the living conditions and habitat of social Aculeatae a series of recommendations have been formulated which can potentially greatly minimize the risk of field re-sting. After a systemic sting reaction, patients should be referred to an allergy specialist for evaluation of their allergy, and if necessary venom immunotherapy (VIT). An emergency medical kit should be supplied, its use clearly demonstrated and repeatedly practised until perfected. This should be done under the supervision of a doctor or a trained nurse. Epinephrine by intramuscular injection is regarded as the treatment of choice for acute anaphylaxis. H1-antihistamines alone or in combination with corticosteroids may be effective in mild to moderate reactions confined to the skin and may support the value of treatment with epinephrine in full-blown anaphylaxis. Up to 75% of the patients with a history of systemic anaphylactic sting reaction develop systemic symptoms once again when re-stung. Venom immunotherapy is a highly effective treatment for individuals with a history of systemic reaction and who have specific IgE to venom allergens. The efficacy of VIT in yellow jacket venom allergic patients has been demonstrated also by assessing health-related quality of life. If both skin tests and serum venom specific IgE turn negative, VIT may be stopped after 3 years. After VIT lasting 3-5 years, most patients with mild to moderate anaphylactic symptoms remain protected following discontinuation of VIT even with positive skin tests. Longer term or lifelong treatment should be considered in high-risk patients. Because of the small but relevant risk of re-sting reactions, in these patients, emergency kits, including epinephrine auto-injectors, should be discussed with every patient when stopping VIT.

[Safety of rush immunotherapy with Hymenoptera venom]

OBJECTIVES

To determine the incidence and nature of adverse events associated with the induction of rush Hymenoptera venom immunotherapy.

MATERIAL AND METHODS

Between 1998 and 2003, we administered venom immunotherapy to 48 patients allergic to bee or wasp venom, by means of a rush immunotherapy protocol (3 days).

RESULTS

We observed no severe adverse reactions in any patients. 12 patients developed only local reactions at the site of injections that did not required any pharmacological treatment. Two patients experienced mild systemic reactions consisting of diffuse urticaria on day 3. Both adverse reactions were treated with intravenous antihistamines.

CONCLUSIONS

Our experience confirms that rapid venom immunotherapy is safe and should be considered in every case especially for patients during the stinging insect season when a rapid protection is required.

Venom immunotherapy: adverse reactions and treatment failure

PURPOSE OF REVIEW

Side effects of venom immunotherapy and lack of efficacy represent significant problems in the treatment of patients allergic to Hymenoptera venom. Among these side effects systemic anaphylactic reactions and large local reactions are the most important. This review aims to discuss new insights in frequency, pathogenesis and handling of these common side effects and of treatment failure during venom immunotherapy.

RECENT FINDINGS

Several studies showed that severe side effects due to venom immunotherapy are rare. Recently published studies focus on ultrarush protocols and report good tolerance of an ultrarush venom immunotherapy in which the maintenance dose was reached within several hours or 2 days, respectively. Compared to the use of aqueous extracts (administered according to a rush protocol), frequency of local and also systemic side effects was lower when depot extracts and schedules with a slow conventional dose increase were applied. Concomitant treatment with H1-antihistamines was found to reduce local and mild systemic adverse reactions during venom immunotherapy. Up to 25% of patients are not protected when re-stung while on venom immunotherapy with the usual maintenance dose of 100 microg of venom every 4-8 weeks. These patients can achieve full protection by increasing the maintenance dose.

SUMMARY

Conventional dose increase using depot extracts is better tolerated than if aqueous extracts are being administered. Concomitant treatment with H1-antihistamines may be helpful. Increasing the venom dose to 200 microg or even more may be therapeutically effective in patients not protected by a lower maintenance dose. To compare tolerance of different treatment protocols prospective comparative studies are required.

Specific immunotherapy in honeybee venom allergy: a comparative study using aqueous and aluminium hydroxide adsorbed preparations

BACKGROUND

For the immunotherapy of Hymenoptera venom allergy various preparations and treatment protocols are in use. However, controlled studies making direct comparisons of the efficacy and safety of different regimens are rare.

OBJECTIVE

To assess prospectively different venom immunotherapy (VIT) protocols using an aqueous or an aluminium hydroxide adsorbed allergen preparation for the treatment of honeybee venom (HBV) allergy.

METHODS

Sixty-five HBV allergic patients (42 males, 23 females; aged 17-75 years) with a history of systemic anaphylactic reactions (SARs) to honeybee stings were treated according to three different regimens. During the incremental phase, patients in group A (n = 21) or B (n = 21) received an aqueous preparation according to a rush protocol. Patients in group C (n = 23) were treated with conventional ("slow") VIT using an aluminium hydroxide adsorbed depot preparation. The maintenance dose was 100 microg venom in all groups. Maintenance treatment in group A was performed with the aqueous preparation administered every 4 weeks, whereas in groups B and C the depot preparation was administered every 8 weeks (group B) or every 4 weeks (group C). A sting challenge test with a living honeybee was performed in 49 patients, 6-12 months after reaching the maintenance dose. Another seven patients were stung accidentally by a honeybee ("field sting").

RESULTS

Treatment with the aqueous preparation evoked large local reactions more frequently than the depot preparation in the dose increase phase [53/693 (7.6%) vs 8/206 (3.9%); P = 0.059] and also in the course of maintenance therapy [85/172 (49.4%) vs 58/478 (12.1%); P < 0.001]. During the dose increase phase, systemic side-effects seemed to occur more frequently in patients on rush VIT with the aqueous preparation compared to patients initially treated with the conventional schedule using the depot preparation [13/42 (31.0%) vs 3/23 (13.0%); not significant). When re-stung by the culprit insect, SARs were observed in 3/20 patients (15.0%) in group A, 2/18 (11.1%) in group B and 3/18 (16.7%) in group C (not significant).

CONCLUSIONS

The aluminium hydroxide adsorbed HBV preparation caused fewer large local reactions than the aqueous preparation. The therapeutic efficacy of the three treatment protocols did not differ.

Rapid venom immunotherapy update

PURPOSE OF REVIEW

This paper will review new indications for the administration of rapid or ultrarush venom immunotherapy and the advantages of pretreatment with antihistamines.

RECENT FINDINGS

Rapid and ultrarush venom immunotherapy protocols have been successfully employed to achieve protective maintenance venom doses rapidly. These have been associated with systemic reactor rates as low as 5-7%. Recently, rapid venom immunotherapy protocols have been successfully employed to reach ultra-high maintenance doses for patients not previously protected with standard maintenance doses (i.e. 100 micro g). There is also evidence that pretreatment with antihistamines before venom injections during rapid venom immunotherapy may reduce the numbers and severity of injection-related systemic reactions, as well as improve long-term outcomes in preventing subsequent resting systemic reactions in the field.

SUMMARY

Pretreatment with antihistamines should be considered in patients receiving rapid or ultrarush venom injections. Ultrarush or rapid immunotherapy regimens compare favorably with conventional modified rush protocols in terms of side-effects, and may be considered in order to achieve higher but effective maintenance venom doses in those rare patients who are treatment failures.

Hymenoptera ultra-rush venom immunotherapy (210 min): a safety study and risk factors

BACKGROUND

In this study, which summarizes our last 5 years of experience, we evaluated the side-effects of ultra-rush venom immunotherapy and the possibility to define some risk factors for side-effects as age, Hymenoptera venom used for treatment, treatment phase, severity of prior insect sting reaction, concentration of skin test positivity, and level of specific IgE.

METHODS

In our protocol on day 1, an initial venom dose of 0.1 microg was followed by 1, 10, 20 microg at 30-min intervals and then 30 and 40 microg at 60-min intervals. Patients who completed this protocol received two booster injections of 50 microg on day 15 and one of 100 microg on day 45. Subsequently, monthly 100 microg boosters were given.

RESULTS

Fifty-one children (9.20 +/- 3.41 years) and 207 adults (40.62 +/- 14.00 years) underwent an ultra-rapid venom immunotherapy (ultra-RVIT). Single ultra-RVIT was administered to 195 patients: 69 with honeybee, 123 with yellow jacket and three with wasp venoms. Two venoms were injected into 59 patients: 42 with yellow jacket and wasp, 17 with yellow jacket and honeybee. Four patients received the three venoms. The frequency of immediate systemic reactions (SR) was not significantly different between adults and children: 11.2% vs. 10.8%. SR were experienced more frequently on day 1 (n= 33). They were uncommon on day 15 (n= 2) and on day 45 (n= 1). No late reactions have been observed. Honeybee venom induced significantly more SR (30%) vs. yellow jacket (3.2%) and wasp venom (6.1%). Among the 33 patients who experienced a SR on day 1, 24 had a reaction grade 1 or 2 and nine had a reaction grade 3 or 4. There is a significant risk for patients with a prior reaction grade 3 or 4 to experience a SR during venom immunotherapy (VIT). The strength of positive skin tests and the level of specific IgE were not related to an increased risk of SR (P= NS).

CONCLUSION

Treatment with honeybee extract induced more SR than the treatment with yellow jacket and wasp venom. Doses increase phase on day 1 is risk factors for SR of ultra-RVIT, as well as the severity of the prior reaction. Age, degree of positive skin tests, and specific IgE are not risk factors.

Molecular aspects of allergy

Atopic diseases such as asthma, rhinitis, eczema and food allergies have increased in most industrialised countries of the world during the last 20 years. The reasons for this increase are not known and different hypotheses have been assessed including increased exposure to sensitising allergens or decreased stimulation of the immune system during critical periods of development. In allergic diseases there is a polarisation of the Th2 response and an increase in the production of type 2 cytokines which are involved in the production of immunoglobulin E and the development of mast cells, basophils and eosinophils leading to inflammation and disease. The effector phase of atopy is initiated by interaction with Fc epsilon RI expressed on effector cells such as mast cells and basophils but also found on an ever increasing list of cells. Binding of a polyvalent allergen to the variable part of IgE leads to a cross-link of the receptor that triggers the cell to release histamine and pharmacological mediators of the symptomatic allergic response. Cross-linking of Fc epsilon RI by autoantibodies against the alpha-chain of the Fc epsilon RI, causing subsequent histamine release is thought to be involved in the pathogenesis of other diseases such as chronic idiopathic urticaria (CIU). To date, most therapeutic strategies are aimed at inhibiting and controlling components of the inflammatory response. Recently, new treatment strategies have emerged that focus on the development of preventive and even curative treatments. The most promising therapeutic approaches are aimed at inhibiting the IgE-Fc epsilon RI interaction with the use of non-anaphylactogenic anti-IgE or anti-Fc epsilon RIalpha autoantibodies. Clinical trials in humans using an humanised anti-IgE antibody showed that this antibody was well tolerated and reduced both symptoms and use of medication in asthma and allergic rhinitis. Thus interruption of the atopic cascade at the level of the IgE-Fc epsilon RI interaction with the use of non-anaphylactogenic antibodies is effective and represents an attractive therapy for the treatment of atopic disease.

Rush Hymenoptera venom immunotherapy: a safe and practical protocol for high-risk patients

BACKGROUND

Hymenoptera venom immunotherapy in allergic patients is a well-established treatment modality for the prevention of systemic anaphylactic reactions caused by insect stings. A variety of therapy regimens exists, from conventional to rush and ultrarush modalities that operate on continuous or intermittent schedules.

OBJECTIVE

The aim of this study was to report the 8-year experience with our rush venom immunotherapy regimen in predominantly high-risk patients and to compare data on safety and convenience with the results of 26 studies published from 1978 to 2001.

METHODS

One hundred one patients allergic to bee, yellow jacket, or hornet venom were treated with rush Hymenoptera venom immunotherapy. Diagnosis and selection of patients for venom immunotherapy were carried out according to the recommendations of the European Academy of Allergology and Clinical Immunology. We used a 4-day regimen, and the incidence and nature of systemic reactions (SRs) were documented. Fifty-two patients were treated with honeybee venom, and 49 were treated with yellow jacket venom.

RESULTS

One hundred (99%) patients reached the maintenance dose. We observed 8 injection-related SRs (0.47% of all injections given) in 7 (6.9%) patients. The number of SRs was higher in patients treated with bee venom extract (12%) compared with in patients receiving yellow jacket venom extract (2%). There was no significant difference in the risk of SRs between female and male patients. The incidence of SRs was considerably lower than the average of 17.8% reported in the literature.

CONCLUSION

With a rush immunotherapy regimen over a time period of 8 years in predominantly high-risk patients, the incidence of SRs was low, despite the high number of patients with bee venom allergy, who are more likely to have side effects. Epinephrine as rescue medication was never necessary, and the regimen proved to be safe and convenient for both the patients and the medical staff.

Adverse events associated with rush hymenoptera venom immunotherapy

OBJECTIVES

To determine the incidence and nature of adverse events associated with the induction of rush Hymenoptera venom immunotherapy.

DESIGN

Retrospective descriptive case study.

SETTING

The asthma and allergy unit at a major metropolitan teaching hospital, between 1 January 1989 and 30 June 1999.

PATIENTS

All patients with anaphylaxis to stings of Hymenoptera insects who received rush venom immunotherapy as inpatients.

OUTCOME MEASURES

Hypersensitivity reactions to venom administration, including angioedema, skin rashes, hypotension and asthma, as well as any other adverse events related to the inpatient stay.

RESULTS

68 venom-allergic patients received 73 courses of rush immunotherapy; 89% were desensitised to honey bee venom, 10% to yellow jacket wasp venom, and one to paper wasp venom. Hypersensitivity reactions occurred after 36 subcutaneous injections (3.8% of all injections given) in 26 patients (38%).

CONCLUSION

In our cohort, immunotherapy was accompanied by a high incidence of adverse systemic events during the induction phase. Immunotherapy should only be given by experienced staff in centres where there are facilities for resuscitation.

Safety of a two-day ultrarush insect venom immunotherapy protocol in comparison with protocols of longer duration and involving a larger number of injections

BACKGROUND

Insect venom immunotherapy (VIT) is initiated by a dose increase protocol administered usually over 7 to 9 days. Shorter protocols have the advantage of reducing the patient's stay in the hospital. Very few data are currently available on the safety of shorter VIT dose increase protocols.

OBJECTIVE

The aim of this study was to investigate whether a reduction in the duration of the VIT dose increase protocol from 7 to 9 days to 2 days causes an increase in the incidence and severity of adverse reactions.

METHODS

Between 1992 and 1997 we administered VIT to 1055 patients allergic to bee or wasp venom. We shortened the 7- to 9-day rush protocol stepwise to 2 days by reducing the number of injections and increasing the initial dose and compared the incidence and severity of adverse reactions. The patients were retrospectively divided into 3 cohorts: 20 injections over 7 to 9 days (cohort 1, 317 patients), 10 to 14 injections over 3 to 6 days (cohort 2, 335 patients), and 9 injections over 2 days (cohort 3, 403 patients).

RESULTS

We observed no severe adverse reactions in any of the cohorts during VIT. Adverse reactions were treated in 7.1% of the patients by oral and in 2.9% by intravenous antihistamines and in 0.8% by systemic corticosteroids. The incidence of adverse reactions declined significantly from 22.4% in cohort 1 to 13.7% in cohort 2 and 10.7% in cohort 3 with reduced number of injections (P <.001).

CONCLUSION

The incidence and severity of adverse reactions decline if the VIT dose increase protocol is shortened to 2 days.

Early effect of ultrarush venom immunotherapy on the IgG antibody response

BACKGROUND

We have previously shown in several allergy models that allergic and tolerance status with respect to allergens is associated with a somewhat different dominant specificity of IgG antibodies. The objective was to test this hypothesis in the compelling model of ultrarush venom immunotherapy (VIT), which induces clinical tolerance after only a few hours of treatment.

METHODS

Antibody titers and specificity were evaluated through solid-phase ELISA using streptavidin-biotin technology in 12 patients allergic to wasp venom before and during the ultrarush procedure (at 12 h, 24 h, and 15 days). The results were compared with those from another group of 20 patients treated with venom injections for at least 2 years.

RESULTS

No significant change was observed in IgG titers during the early phase of VIT. The capacity of individual sera to prevent the antigen binding of pooled IgG from allergic patients changed rapidly, with mean percentage inhibitions falling from 80+/-15%, before starting VIT, to 26+/-14%, 35+/-15%, and 34+/-5% after 12 h, 24 h, and 15 days of treatment, respectively (P<0.001 by one-way ANOVA). The capacity of individual sera to prevent the antigen binding of pooled IgG from patients receiving prolonged VIT changed, with mean percent inhibitions increasing from 47+/-8%, before starting VIT, to 76+/-7%, 83+/-6%, and 87+/-6% after 12 h, 24 h, and 15 days of treatment, respectively (P<0.001 by one-way ANOVA).

CONCLUSIONS

During the initial phase of ultrarush VIT, a change in IgG specificity, i.e., a change in the set of epitopes dominantly recognized by IgG on wasp-venom antigens, occurred concomitantly with early clinical tolerance and was already detectable a few hours after the onset of treatment. Although it may be an epiphenomenon, this change represents the earliest humoral modification described so far during this procedure. The mechanism is unknown, but it appears to be a selective depletion of the highest avidity antibody fraction by the venom injected in large doses at this stage of therapy. Finally, our data now show the previously documented association between a particular IgG specificity and the clinical status (allergy vs tolerance) to be true also with ultrarush VIT, a model in which the clinical ability to display allergic symptoms is rapidly reversed.

Modified antigenic reactivity of anti-phospholipase A2 IgG antibodies in patients allergic to bee venom: conversion with immunotherapy and relation to subclass expression

BACKGROUND

We have previously reported that, in addition to modifying IgG levels and subclass distributions, wasp venom immunotherapy (VIT) rapidly changes IgG antibody specificity.

OBJECTIVES

We investigated whether such a change can be documented in the IgG response to the major bee venom allergen, phospholipase A2 (PLA2), from patients allergic to bees treated with VIT; whether it is coupled to the shift in IgG subclass distribution (IgG4 predominance) usually observed during VIT; and whether it restores the specificity displayed by IgG antibodies from nonallergic individuals.

METHODS

Antibody specificity was evaluated in 17 patients allergic to bee venom in competitive ELISAs by using streptavidin biotin technology. Patients were tested before and during specific immunotherapy (at 15 days and 6 months) and compared with another group of 17 patients treated with venom injections for at least 2 years (VIT patients) and 30 healthy individuals.

RESULTS

The capacity of individual sera to prevent PLA2 binding of pooled IgG from allergic patients changed rapidly with mean percentage inhibitions falling from 84% +/- 14% before starting VIT to 27% +/- 13% and 28% +/- 7% after 15 days and 6 months of treatment, respectively (p < 0.001 by one-way analysis of variance [ANOVA]). IgG titers were only slightly increased. The capacity of individual sera to prevent the binding of pooled IgG from patients receiving VIT changed rapidly with mean percentage inhibition increasing from 60% +/- 12% before starting VIT to 85% +/- 6% and 82% +/- 6% after 15 days and 6 months of treatment, respectively (p < 0.001 by one-way ANOVA). Similar results were found regardless of whether pooled IgG1 or pooled IgG4 were used.

CONCLUSION

VIT results in a rapid change in the antigenic reactivity of anti-PLA2 IgG antibody of human allergic sera, restoring, although not completely, the specificity peculiar to lgG from healthy individuals. This suggests that allergic status and immunoprotection correlate with the preferential expression of distinct IgG specificities, which appear equally distributed over the IgG1 and IgG4 antibody subclasses. It is, however, not known whether the shift in IgG specificity is one of the operative mechanisms of VIT.

Wasp venom immunotherapy changes IgG antibody specificity

BACKGROUND

The evolution of the IgG response during venom immunotherapy (VIT) has been previously investigated in terms of antibody titres and subclasses.

OBJECTIVES

The present work studied the evolution of IgG antibody fine specificity in wasp allergic patients treated with rush VIT.

METHODS

Antibody specificity was evaluated in 51 wasp allergic patients in competitive ELISA using streptavidin biotin technology. Patients were tested before and during specific rush immunotherapy (at 15 days, 6 months, 12 months) and compared with 44 patients treated by venom injections for at least 2 years.

RESULTS

The capacity of sera to prevent the antigen binding of pooled IgG from allergic patients changed rapidly with mean percentage inhibitions (+/-SD) falling from 70+/-11-51+/-18% after 15 days of treatment (P<0.001 by one way ANOVA). Similarly, the antigen binding capacity of pooled IgG from VIT patients was differently prevented by sera with mean percentage inhibitions increasing from 37+/-12-65+/-8 after 15 days of treatment (P< 0.0001 by one-way ANOVA).

CONCLUSIONS

The immunodominance pattern of IgG epitopes recognized on wasp venom antigens by sera from wasp allergic patients changes soon after initiating rush VIT. Further studies will indicate whether, instead of measuring IgG titres, this marked change could be used as the basis of a new test for monitoring the outcome of VIT.

Hymenoptera sting challenge of 348 patients: relation to subsequent field stings

BACKGROUND

Patients with a history of a serious anaphylactic reaction after a Hymenoptera sting are usually given venom immunotherapy. Because the natural history of Hymenoptera sting anaphylaxis is often of a declining severity, there is a chance of overtreatment.

OBJECTIVE

Identification of patients at risk for a future anaphylactic reaction may reduce the number of patients who need venom immunotherapy.

METHODS

We investigated the relation between the grade of hypersensitivity to an in-hospital sting challenge and the reaction to a subsequent accidental field sting. From 1982 through 1992, 348 patients with mild or no symptoms after a sting challenge were not given venom immunotherapy. All patients were asked by letter whether they had experienced a subsequent field sting. In case of a sting, the severity of the reaction was further evaluated.

RESULTS

Information could be obtained from 327 patients: 129 had been re-stung, and 110 of them had only had a local reaction. Thirteen patients had experienced mild systemic symptoms, and six patients had experienced serious manifestations. In two of the latter group hypotension was observed.

CONCLUSION

In 95% of patients with a previous anaphylactic reaction, the result of the in-hospital sting challenge provided a good prediction of tolerance to a subsequent Hymenoptera field sting.

Ultra rush bee venom immunotherapy does not reduce cutaneous weal responses to bee venom and codeine phosphate

BACKGROUND

The rapid administration of bee venom in cumulative doses exceeding the quantity contained in one bee sting is well tolerated by most of the patients during 3.5 h of ultra-rush bee venom immunotherapy (VIT). The mechanism of this tolerance is unknown.

OBJECTIVE

The aim of the study was to verify the hypothesis that either slow mediator depletion of mast cells or blockade of their surface receptor mechanisms by increasing doses of allergen might be the major mechanisms of tolerance induced by ultra-rush VIT.

METHODS

Nine bee venom allergic patients with a history of severe systemic reactions after a bee sting, positive skin tests and bee venom specific serum IgE antibodies were treated as follows: on the first day a cumulative dose of 111 micrograms was administered over 3.5 h under intensive care conditions. Further injections were given on day 7, day 21 and thereafter at 4 week intervals. Intradermal tests with codeine phosphate (non-specific mast cell degranulation) and bee venom were performed before the initiation of VIT and 30 min after the last injection on the same day as well as before the subsequent bee venom injections.

RESULTS

No significant changes of skin reactivity to both codeine phosphate and bee venom were observed on day 1 (before initiation of VIT and after the last injection on the same day).

CONCLUSIONS

Ultra-rush VIT does not induce mediator depletion or surface receptor blockade in skin mast cells.

Safety considerations in assessing the role of immunotherapy in allergic disorders

Specific immunotherapy (SIT) is accepted as an effective treatment of allergic diseases when high quality extracts are used. However, this form of treatment can cause untoward reactions among which systemic reactions are the most severe. Although life-threatening reactions are rare and deaths exceptionally reported, SIT should be prescribed by allergists to patients with well defined characteristics, and administered with care by (or under the close supervision of) physicians trained to deal rapidly with the reactions. Reactions with standardised extracts occur mostly during the dose increase phase but they can be prevented using adapted schedules and premedication. During maintenance injections or when vial batches are changed, standardised extracts of known shelf-life usually result in a low rate of systemic reactions. Patients with asthma are more prone to develop systemic reactions, and allergens should not be administered to patients with a forced expiratory volume in 1 second (FEV1) under 70% of predicted or in those who have unstable or symptomatic asthma. Systemic reactions may be observed with all allergens and allergenic preparations although it appears that high molecular weight extracts may be safer.

Rapid Hymenoptera venom immunotherapy: comparative safety of three protocols

We compared 284 sting-allergic patients treated with either a 4 day (group 1), 6 hr (group 2) or 210 min (group 3) rapid venom immunotherapy (RVIT) protocol using honey bee (HB) or yellow jacket (YJ) venom at cumulative doses of 527.6 micrograms, 226.6 micrograms and 101.1 micrograms respectively. The 4 day protocol involved four times as many injections as the 210 min protocol and twice as many as the 6 hr protocol. Desensitization was conducted in a hospital providing full emergency resuscitation facilities. In group 1, 1 x 100 micrograms boosters were given on days 7, 10, 15 and 45 and, in groups 2 and 3, 2 x 50 micrograms boosters were given on day 15 and 1 x 100 micrograms on day 45. The patients in the three groups were comparable with regard to clinical characteristics and immunological reactivity determined by skin tests. All patients had large local reactions. Systemic reactions (SR) occurred in 28.2% of patients in group 1, 28.6% in group 2 and 6.9% in group 3. The mean total cumulative venom dose (s.e.m.) for occurrence of SR was 123.75 (+/- 24.2) in group 1, 183.27 (+/- 28.5) in group 2, and 36.43 (+/- 9.3) in group 3. HB led to more systemic reactions than YJ venom. The rate of SR decreased when the cumulative venom dose was reduced during RVIT. The median dose was 137.6 micrograms in group 1, 226.6 micrograms in group 2, and 21.1 micrograms in group 3. No systemic reactions were observed after the booster injections. The results of this study suggest that short RVIT protocols with low cumulative doses carry a lesser risk of SR.

Immunotherapy with Hymenoptera venoms. Position paper of the Working Group on Immunotherapy of the European Academy of Allergy and Clinical Immunology

Immunotherapy with Hymenoptera venoms is widely used throughout the world and is accepted as an effective treatment for most patients with Hymenoptera venom allergy. There are, however, still some unresolved problems with this form of treatment. At present there is no definite test which makes it possible to identify patients at risk - and thus candidates for immunotherapy - unequivocally. On the basis of prospective studies on the natural history of Hymenoptera allergy, venom immunotherapy is indicated in adults with severe systemic anaphylaxis. It is usually not necessary in patients with large local reactions only. Children with mild systemic reactions, e.g. urticaria, will need immunotherapy only in case of repeated reactions and/or a high risk of re-exposure. The selection of venoms for immunotherapy may lead to some confusion owing to common antigenic determinants shared by venoms of various Hymenoptera species. Many different regimens for immunotherapy have been proposed. At present, the three main are: rush, stepwise or clustered and classical. The maintenance dose of 100 micrograms usually protects from life-threatening reactions. However, in some patients 200 micrograms are necessary for complete protection. The usual interval between maintenance injections is 4 to 6 weeks. In many patients a strong increase of venom specific serum IgG-antibodies usually parallels clinical protection induced by venom immunotherapy, although many exceptions have been reported. Allergic side effects of venom immunotherapy are not rare, especially with honey bee venom and during the initial phase of dose increase. The question of the duration of venom immunotherapy is handled differently: although some authors recommend treatment for life, most suggest treating patients until skin tests and RAST become negative.

Provocation test with a living insect as a diagnostic tool in systemic reactions to bee and wasp venom: a prospective study with emphasis on the clinical aspects

The use of the sting challenge (SC) in insect allergy has brought into doubt the widely held belief that clinical data, specific IgE and the skin test are reliable tools in diagnosis and decision making with regard to therapy. We subjected ninety patients, known to have a systemic reaction to SC, in the Intensive Care Unit. Of these patients, 28% once more showed a systemic reaction; 72% had only a local reaction. No statistically significant difference could be demonstrated between positive and negative SC patients with regard to age; sex; the presence of allergic disease(s)--other than allergy to insects--and the severity of the preceding systemic reaction; the sting site and the related time interval; or specific IgE, IgG1, IgG4, their ratios and the skin test. A negative skin test and/or specific IgE, however, does not exclude the possibility of a recurrent systemic reaction. The long-term value of the SC appeared to be good since the results of the revision SC remained unchanged. Skin test and specific IgE are useful as diagnostic tools in establishing the insect concerned. SC provides information on the likelihood of a recurrent systemic reaction.

Immunotherapy with yellow jacket venom. A comparative study including three different extracts, one adsorbed to aluminium hydroxide and two unmodified

Thirty-two patients with previous systemic allergic reaction to yellow jacket stings were randomly allocated to three groups receiving immunotherapy with different preparations of yellow jacket venom: 1) extract adsorbed to aluminium hydroxide (Alutard-SQ), 2) Pharmalgen extract or 3) non-adsorbed extract from Allergologisk Laboratorium (ALK aq.). Regular examinations showed a decrease in skin prick test size in nearly all patients. Specific IgE-antibody (RAST and CRIE scores) showed a similar, but not significant tendency to decrease in all three groups. Specific IgG-antibody increased considerably in the Alutard group only; after 2 years, however, no difference could be detected between the three groups. During dose increase, patients treated with ALK aq. generally had smaller local reactions to injections than those treated with Pharmalgen. Few systemic reactions occurred in all three groups. Nineteen patients treated for 2 1/2-3 1/2 years were challenged in-hospital with stings from yellow jackets. No systemic and only minor local reactions occurred. Consequently, with the dose regimens applied all three extracts seem effective even though no common changes in either specific IgE or IgG could be demonstrated.

Reproducibility of skin sensitivity using a quantitative skin prick test

The reproducibility of repeated quantitative skin prick test titrations was evaluated in seven asthmatic patients tested 2-4 times within 6 weeks. The skin sensitivity was estimated as endpoint titration and histamine equivalent reaction using both 1 and 10 mg/ml histamine dihydrochloride. The histamine equivalent reaction had a significantly higher reproducibility compared to endpoint titration, with a coefficient of variation less than 10% for histamine 10 mg/ml. Further, using this histamine concentration, the deviation in repeated testing was for practical purposes less than 0.5 log step. The same constancy in skin sensitivity was found in one patient tested 3 times and then retested another 3 times 6 months later by a different tester. The results indicate that the quantitative skin prick test and histamine-estimated skin sensitivity have a clinical application in the assessment of pharmacologically or immunotherapy-induced changes in the releasability of skin mast cells.