Early effect of ultrarush venom immunotherapy on the IgG antibody response

Intralymphatic Immunotherapy (ILIT) With Bee Venom Allergens: A Clinical Proof-of-Concept Study and the Very First ILIT in Humans

Background

Subcutaneous venom immunotherapy (VIT) represents an effective treatment against bee venom allergy. However, it involves long treatment times, high costs, and the risk of adverse events (AEs). Shorter, safer, and cheaper treatment options are therefore pursued.

Objective

To determine the safety, immunogenicity, and efficacy of bee venom intralymphatic immunotherapy (ILIT).

Methods

In an open pilot study, 12 patients received bee venom ILIT in three sessions with 14-day intervals: 0.1–5 μg/dose. Ultrasound imaging was applied to guide an injection and to document the lymph node structure. In a second study, 67 patients from 15 centers in Europe and Australia were randomized to receive four doses of either 10- or 20-μg bee venom ILIT with 28-day intervals. Clinical endpoints included specific IgE and IgG and protection after a bee sting challenge. These studies were performed in the years 2000–2003.

Results

In a proof-of-concept study, no serious AEs were observed. An increase in allergen-specific IgG1 but no IgG4 and IgE was observed. ILIT induced the protection against a bee sting challenge in 7 out of 8 challenged patients. In a multicenter study, an increase in allergen-specific IgG and IgE was observed, with the highest increase in patients receiving a higher ILIT dose. The study was terminated due to several serious AEs upon the sting challenge provocation after the completion of treatment. However, out of 45 patients challenged, 15 (65%) and 18 (82%) patients in the 10- and 20-μg group, respectively, showed an improvement of two grades or more. No correlation was observed between antibody levels and sting protection.

Conclusions

While a pilot study suggested the safety and efficacy of bee venom ILIT, a high number of AEs seen after the sting challenge following a randomized study indicate that the immunology protection offered by bee venom ILIT is insufficient. Of note, the bee venom allergen extract used in the two studies were from the two different providers. While the first study used a formulation approved for use in subcutaneous VIT, the second study used a nonapproved formulation never tested in humans. Further studies on approved formulations should be performed to generate conclusive results regarding the safety and efficacy of bee venom ILIT.

Hymenoptera Venom Allergy: How Does Venom Immunotherapy Prevent Anaphylaxis From Bee and Wasp Stings?

Hymenoptera stings may cause both local and systemic allergic reactions and even life threatening anaphylaxis. Along with pharmaceutical drugs and foods, hymenoptera venom is one of the most common causes of anaphylaxis in humans. To date, no parameter has been identified that may predict which sensitized people will have a future systemic sting reaction (SSR), however some risk factors, such as mastocytosis and age >40 years are known. Venom immunotherapy (VIT) is the most effective method of treatment for people who had SSR, which is shown to be effective even after discontinuation of the therapy. Development of peripheral tolerance is the main mechanism during immunotherapy. It is mediated by the production of blocking IgG/IgG4 antibodies that may inhibit IgE dependent reactions through both high affinity (FcεRI) and low affinity (FcεRII) IgE receptors on mast cells, basophils and B cells. The generation of antigen specific regulatory T cells produces IL-10 and suppresses Th2 immunity and the immune responses shift toward a Th1-type response. B regulatory cells are also involved in the production of IL-10 and the development of long term immune tolerance. During VIT the number of effector cells in target organs also decreases, such as mast cells, basophils, innate type 2 lymphocytes and eosinophils. Several meta-analyses and randomized controlled studies have proved that VIT is effective for preventing SSR to a sting and improves the quality of life. In this review, the risk of SSR in venom allergy and how VIT changed this risk are discussed.

Biomarkers for Allergen Immunotherapy: A "Panoromic" View

Biomarkers (BMKs) are biological parameters that can be measured to predict or monitor disease severity or treatment efficacy. The induction of regulatory dendritic cells (DCs) concomitantly with a downregulation of proallergic DC2s (ie, DCs supporting the differentiation of T-helper lymphocyte type 2 cells) in the blood of patients allergic to grass pollen has been correlated with the early onset of allergen immunotherapy efficacy. The combined use of omics technologies to compare biological samples from clinical responders and nonresponders is being implemented in the context of nonhypothesis-driven approaches. Such comprehensive "panoromic" strategies help identify completely novel candidate BMKs, to be subsequently validated as companion diagnostics in large-scale clinical trials.

Update on immune mechanisms associated with sublingual immunotherapy: practical implications for the clinician

Sublingual immunotherapy (SLIT) is established as a safe and efficacious treatment for patients with type I respiratory allergies. The ability of SLIT to elicit antigen (allergen)-specific tolerance is linked to the peculiar biology of oral antigen-presenting cells. In the absence of danger signals, Langerhans cells, myeloid dendritic cells, and macrophages located in oral tissues, tonsils, and draining cervical lymph nodes are biased toward the induction of T(H)1 and IL-10-producing CD4(+) regulatory T cells, thus supporting tolerance as opposed to inflammation. Sublingual administration does not lead to any detectable systemic exposure of intact allergens nor to IgE neosensitization. Oral tissues contain limited numbers of mast cells located in submucosal areas, thereby explaining the well-established safety profile of SLIT, with mostly local but rare systemic reactions. The induction of CD4(+) regulatory T cells and blocking anti-inflammatory IgGs or IgAs are considered important for tolerance induction after SLIT. Specific molecular signatures associated with tolerogenic dendritic cells were recently reported during the onset of SLIT efficacy in the peripheral blood of patients exhibiting clinical benefit. Collectively, these observations confirm the induction of strong allergen-specific suppressive/tolerogenic immune responses during SLIT and pave the ground for the identification of biomarkers of efficacy. Practical implications of this emerging scientific knowledge are presented (1) to support the rational design of second-generation sublingual vaccines based on purified allergens, vector systems and/or adjuvants and (2) to help the clinician in decision making during his/her practice.

Novel developments in the mechanisms of immune tolerance to allergens

Allergy is the result of a disbalanced immune response to environmental innocuous antigens. Despite of accumulating data to define the pathomechanisms that take place in case of allergic diseases a detailed understanding of sequence of events that lead to the "normal" scenario of tolerance development are still under debate. Allergen-specific immunotherapy is the only causal treatment of allergic diseases. It modifies the immune response to a particular antigen to achieve tolerance against the symptom-causing allergen. This process is considered to mirror physiological peripheral tolerance induction. A number of immunological changes have been described to occur under allergen immunotherapy, including the generation of allergen-specific regulatory T cells, the induction of allergen-specific IgG4, an increase in the Th1/Th2 cytokine ratio and decreased activation and function of effector cells such as mast cells, basophils and eosinophils.

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.

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.

Allergen immunotherapy: immunomodulatory treatment for allergic diseases

Allergen immunotherapy is currently the only immune-modifying treatment for allergic disease. At the present time it is indicated for the treatment of allergic rhinitis, asthma and venom hypersensitivity. Efficacy appears to be dose dependent, and the immunological mechanisms responsible for the clinical efficacy of immunotherapy are still being elucidated. Immunological changes associated with immunotherapy include induction of T regulatory cells, increase in allergen-specific immunoglobulin G4, increase in interleukin-10 production and downregulation of the T helper 2 response. The disadvantages of allergen immunotherapy include risk of adverse events and patient time and inconvenience. Risks of immunotherapy range from large local reactions to mild systemic reactions, such as rhinitis. Fatalities from immunotherapy injections have been reported at a rate of approximately one fatality per 2.5 million injections. Conventional subcutaneous immunotherapy build-up schedules involve administration of a single-dose increase each visit and it may take several months before a patient achieves the therapeutic maintenance dose. Accelerated schedules, such as rush and cluster, will allow the patient to achieve the maintenance dose sooner but there may be a greater risk of a systemic reaction. The current focus of immunotherapy research is to develop safer and more effective vaccines. Another approach to enhancing immunotherapy safety is through an alternative delivery method. Sublingual immunotherapy is clearly safer than subcutaneous immunotherapy, but further investigation is needed to determine optimal dose and appropriate patient selection.

Peanut epitopes for IgE and IgG4 in peanut-sensitized children in relation to severity of peanut allergy

BACKGROUND

Better understanding of the relationship between antibody response to peanut and clinical sensitivity might lead to more accurate prognostication.

OBJECTIVE

We sought to investigate peanut-specific IgE and IgG4 epitope diversity in relation to challenge-defined clinical sensitivity to peanut in a group of peanut-sensitized children.

METHODS

Clinical sensitivity was determined by means of double-blind, placebo-controlled peanut challenges in 24 sensitized children. Six atopic control subjects were included. Specific IgE and IgG4 binding to 419 overlapping 15-amino-acid peptides representing the sequence of recombinant Ara h 1, Ara h 2, and Ara h3 was analyzed by means of microarray immunoassay.

RESULTS

Peanut-sensitized patient sera bound significantly more IgE and IgG4 epitopes than control sera. This patient group reacted to the same Ara h 1, Ara h 2, and Ara h 3 epitopes as reported previously. There was a positive correlation between IgE epitope diversity (ie, number of epitopes recognized) and clinical sensitivity (r = 0.6), such that patients with the greatest epitope diversity were significantly more sensitive than those with the lowest diversity (P = .021). No specific epitopes were associated with severe reactions to peanut. IgG4 binding was observed to largely similar epitopes but was less pronounced than IgE binding and did not relate to the clinical sensitivity to peanut. IgE and IgG4 epitope-recognition patterns were largely stable over a 20-month period.

CONCLUSION

Clinical sensitivity, as determined by means of double-blind, placebo-controlled peanut challenge, is positively related to a more polyclonal IgE response, which remains stable over time.

Duration of allergen immunotherapy in respiratory allergy: when is enough, enough?

OBJECTIVES

To investigate the duration of effective inhalant subcutaneous immunotherapy (SCIT) reported in the published literature and to determine if any specific biomarkers or clinical predictors exist that may identify patients who will remain in long-term remission after discontinuing treatment.

DATA SOURCES

Articles were selected from a search of the PubMed database from 1976 to 2006 using the search terms immunotherapy and allergen immunotherapy in combination with venom, allergic rhinitis, asthma, mechanism, efficacy, and duration, as well as articles known to the authors and referenced in review articles.

STUDY SELECTION

Articles were selected if evaluation of efficacy of the primary allergic disease treated after discontinuation of SCIT was stated as one of the objectives of the study.

RESULTS

The rate of relapse after discontinuing SCIT ranges from 0% to 55% of patients in the studies reviewed in this article. The length of the specific allergen immunotherapy and allergen type (ie, perennial vs seasonal) may be variables that affect the duration of clinical remission after cessation of SCIT. One study found the duration of SCIT efficacy after discontinuation depended on duration of treatment and correlated with decrease in skin test reactivity.

CONCLUSION

Until specific tests or clinical markers are identified that will clearly distinguish between patients who will relapse from those who will remain in long-term clinical remission after discontinuing effective allergen immunotherapy, the decision to continue or stop immunotherapy must be individualized.

Mechanisms of immunotherapy in allergic rhinitis

Allergic rhinitis is a common condition, but many people still experience suboptimal control of symptoms despite measures such as allergen avoidance, intra-nasal steroids and antihistamines. Specific immunotherapy (SIT) has been used for many years, but though many studies show clinical efficacy, its mechanism of action is still not clearly understood. Earlier studies showed changes in antibodies and it may be that SIT works through mechanisms that alter the ratio of 'protective' IgG4 to 'pro-allergenic' IgE. Other studies have shown a reduction in eosinophil migration to nasal mucosa as well as a reduction in inflammatory mediator release including basophil histamine release. More recent studies have proposed that SIT works through inhibition of T-helper 2 lymphocytes (Th2) which preferentially produce cytokines that promote allergic responses. SIT may cause a deviation from Th2 to Th1 (T-helper 1 lymphocytes) or may induce T-regulatory cells (T-regs) which inhibit Th2 responses directly or through inhibitory cytokines.

Sublingual immunotherapy of allergic diseases

The only disease-modifying treatment that is available for allergic patients is allergen-specific immunotherapy. Two competing application forms are used: subcutaneous immunotherapy, which has been used for > 90 years, and a relatively new immunotherapy where the allergen is applied sublingually. Numerous studies have shown efficacy for subcutaneous immunotherapy and have identified possible mechanisms that are responsible for the observed reduction in allergic responses. In contrast, the efficacy of sublingual immunotherapy has not been documented to the same degree and the responsible immunological mechanisms have not yet been clearly defined. This review focuses on the published clinical and experimental data on sublingual immunotherapy and points at possible mechanisms of how sublingual immunotherapy may differ from subcutaneous immunotherapy in its mode of action, and also discusses the potential advantages and pit falls of both therapies.

Accelerated immunotherapy schedules: review of efficacy and safety

OBJECTIVE

To provide a comprehensive evaluation of accelerated immunotherapy build-up schedules in terms of adverse reactions and clinical efficacy.

DATA SOURCES

Peer-reviewed studies and review articles were selected from the PubMed database for articles published in the years 1976 to 2006 using the following keywords: rush, cluster immunotherapy in combination with allergic rhinitis, asthma, Hymenoptera, and imported fire ant.

STUDY SELECTION

Studies were selected if they provided safety and efficacy information on accelerated allergen immunotherapy schedules. Most of the studies reviewed were double-blind, placebo controlled, but some open-observational studies were included if they provided immunotherapy safety or other information the author thought was relevant.

RESULTS

A wide range of systemic reactions were reported in the literature with inhalant allergens: ranging from 27% to 100% of the patients in rush immunotherapy studies and 0% to 79% of patients in the cluster studies. Predictors of systemic reactions with rush immunotherapy were forced expiratory volume in 1 second less than 80% of predicted and a high degree of skin test reactivity. Premedication clearly reduces the risk of systemic reactions with rush immunotherapy, but the effect on cluster schedules was not as clear.

CONCLUSION

Accelerated immunotherapy build-up schedules in selected patients may provide a rapid alternative to conventional build-up schedules without a significant increase in risk.

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.

Specific ultrarush desensitization in Hymenoptera venom-allergic patients

BACKGROUND

Hymenoptera venom hypersensitivity is an epidemiologically important problem. The only effective treatment in the management of venom-allergic patients with a history of generalized reactions to insect sting is specific immunotherapy.

OBJECTIVE

To demonstrate safety and effectiveness of a modified ultrarush desensitization protocol in venom-allergic patients.

METHODS

Fifty-seven patients with Hymenoptera venom allergy underwent a specific 1-day ultrarush desensitization by the subcutaneous route, reaching the cumulative dose of 101.1 microg in 2.5 hours. The maintenance dose (100 microg) was administered after 15 days and thereafter once a month. Patients were followed up for a year. Antihistamines were withheld for 15 days before and during desensitization to not underestimate the incidence of adverse effects.

RESULTS

All patients but I completed the ultrarush desensitization. (This patient discontinued the treatment because of a hypertensive crisis not related to the desensitization.) The treatment caused a rapid variation of immunological parameters (IgE, IgG4) since the 15th day. After the desensitization, skin prick test results became negative in 15 patients (27%, decrease of 3.5 log), whereas they decreased in 14 patients (25%, decrease of 1 log). Sixty-four percent showed no adverse effects. Only 7% had a mild systemic reaction.

CONCLUSIONS

Ultrarush desensitization is an effective and safe therapy in the management of patients with Hymenoptera venom allergy. In fact, it provides a faster tolerance, without significant differences regarding incidence of severe adverse effects, compared with traditional and rush protocols. It can be adopted for all patients, even children and teenagers.