Injection immunotherapy. British Society for Allergy and Clinical Immunology Working Party

Safety and adverse reactions in subcutaneous allergen immunotherapy: a review

BACKGROUND

Allergen immunotherapy (AIT) is the only treatment which acts on the causes of allergic diseases by modifying their natural history. In the eighties subcutaneous immunotherapy (SCIT) with high biological power allergen extracts caused a number of severe systemic reactions and also fatalities in the UK and the US, resulting in its limitation and in the introduction of other routes of administration. A decisive advance for SCIT safety was understanding that the major cause of mortality was injecting the allergen extract to patients with uncontrolled asthma at the time of injection.

AREAS COVERED

This awareness resulted in a significant decrease in fatalities, but not in their abolition. In 2019, an increase in SCIT-related mortality was observed, suggesting to continue the research for still unidentified factors favoring severe reactions, such as the administration of a wrong extract or of allergen doses higher than listed, unintentional intravenous administration, and missed dose reduction after protracted interruption. Moreover, in the context of the improving of the safety, the role played in tolerance-promoting by adjuvants such as CpG oligodeoxynucleotides has to be taken into account, as well as the potential preventive effect performed by the monoclonal anti-IgE antibody omalizumab against the exacerbation of severe reactions during SCIT.

CONCLUSION

The safety of SCIT is good, but the research to improve it further must continue. In particular, the pathophysiological mechanisms related to AIT for inhalants and for Hymenoptera venom should be studied, based on the evident diversity demonstrated by the complete absence of fatal reactions to Hymenoptera venom immunotherapy from its introduction in comparison with the history of serious and fatal offenses examined in this review.

Venom Immunotherapy and Aeroallergen Immunotherapy: How Do Their Outcomes Differ?

Allergen immunotherapy (AIT) and venom immunotherapy (VIT) are meant to work on the causes of allergies, respectively, to respiratory allergens and Hymenoptera venom, inducing tolerance to the allergens and modifying the natural history of allergy. Both types of immunotherapies have evidence of efficacy, but actually they present wide differences in both effectiveness and safety. Indeed, as far as the effectiveness of VIT is concerned, if the protection against fatal reactions to stings is considered as the primary objective, more than 40 years of clinical practice demonstrate complete success. The clinical success of AIT is measurable on the basis of reduction or disappearance of allergic symptoms. The difference between the two treatments is even higher as regards safety: AIT has been concerned in the past by a series of fatal reactions caused, which underwent a progressive decrease when it was understood that they were related to the presence of uncontrolled asthma. However, fatal reactions related to failure to recognize the presence of risk factors or administration errors are still reported. Similarly to what has been observed for efficacy, VIT has never been affected by fatal reactions to the administration of venom, and the most important risk of anaphylaxis, which is the concomitance of mastocytosis, is now identified by measuring its marker serum tryptase. To date, mechanisms of hypersensitivity reactions that differentiate respiratory allergy from Hymenoptera venom allergy have not been successfully demonstrated. We have examined the past and present literature in order to propose reasonable hypotheses about the mechanisms actually involved.

Mold allergens in respiratory allergy: from structure to therapy

Allergic reactions to fungi were described 300 years ago, but the importance of allergy to fungi has been underestimated for a long time. Allergens from fungi mainly cause respiratory and skin symptoms in sensitized patients. In this review, we will focus on fungi and fungal allergens involved in respiratory forms of allergy, such as allergic rhinitis and asthma. Fungi can act as indoor and outdoor respiratory allergen sources, and depending on climate conditions, the rates of sensitization in individuals attending allergy clinics range from 5% to 20%. Due to the poor quality of natural fungal allergen extracts, diagnosis of fungal allergy is hampered, and allergen-specific immunotherapy is rarely given. Several factors are responsible for the poor quality of natural fungal extracts, among which the influence of culture conditions on allergen contents. However, molecular cloning techniques have allowed us to isolate DNAs coding for fungal allergens and to produce a continuously growing panel of recombinant allergens for the diagnosis of fungal allergy. Moreover, technologies are now available for the preparation of recombinant and synthetic fungal allergen derivatives which can be used to develop safe vaccines for the treatment of fungal allergy.

Sublingual or subcutaneous immunotherapy for seasonal allergic rhinitis: an indirect analysis of efficacy, safety and cost

RATIONALE, AIMS AND OBJECTIVES

The standard of preventive care for poorly controlled seasonal allergic rhinitis (AR) is subcutaneous immunotherapy (SCIT) with allergen extracts, administered in a physician's office. As an alternative to SCIT, sublingual immunotherapy (SLIT) is now an option for patients with seasonal AR. Oralair, a SLIT tablet containing freeze-dried allergen extracts of five grasses [cocksfoot (Dactylis glomerata), meadow grass (Poa pratensis), rye grass (Lolium perenne), sweet vernal grass (Anthoxanthum odoratum) and timothy grass (Phleum pratense)], and Grazax, a SLIT tablet containing a standardized extract of grass pollen allergen from timothy grass (P pratenase), are two such agents currently available in many countries. However, head-to-head comparative data are not available. In this study, an indirect comparison on efficacy, safety and cost was undertaken between Oralair, Grazax and SCIT.

METHODS

A systematic review was conducted for double-blind placebo-controlled randomized trials evaluating Oralair, Grazax or SCIT in patients with grass-induced seasonal AR. Using placebo as the common control, an indirect statistical comparison between treatments was performed using meta regression analysis with active drug as the primary independent variable. An economic analysis, which included both direct and indirect costs for the Canadian setting, was also undertaken.

RESULTS

Overall, 20 placebo-controlled trials met the study inclusion criteria. The indirect analysis suggested improved efficacy with Oralair over SCIT [standardized mean difference (SMD) in AR symptom control = -0.21; P = 0.007] and Grazax (SMD = -0.18; P = 0.018). In addition, there were no significant differences in the risk of discontinuation due to adverse events between therapies. Oralair was associated with cost savings against year-round SCIT ($2471), seasonal SCIT ($948) and Grazax ($1168) during the first year of therapy.

CONCLUSIONS

Oralair has at least non-inferior efficacy and comparable safety against SCIT and Grazax at a lower annual cost.

A limited CpG-containing oligodeoxynucleotide therapy regimen induces sustained suppression of allergic airway inflammation in mice

BACKGROUND

CpG-containing oligodeoxynucleotides (CpG-ODNs) are potent inhibitors of T helper 2 mediated allergic airway disease in sensitised mice challenged with allergen. A single treatment has transient effects but a limited series of treatments has potential to achieve clinically meaningful sustained inhibition of allergic airway disease.

OBJECTIVE

To optimise the treatment regimen for sustained efficacy and to determine the mechanisms of action in mice of an inhaled form of CpG-ODN being developed for human asthma treatment.

METHODS

We set up a chronic allergic-asthma model using ragweed-sensitised mice exposed weekly to intranasal ragweed. Using this model, the effects of a limited series of weekly intranasal 1018 ISS (CpG-ODN; B-class) treatments were evaluated during treatment and for several weeks after treatments had stopped but weekly allergen exposures continued. Treatment efficacy was evaluated by measuring effects on lung T helper 2 cytokines and eosinophilia, and lung dendritic cell function and T-cell responses.

RESULTS

Twelve intranasal 1018 ISS treatments induced significant suppression of bronchoalveolar lavage eosinophilia and interleukin 4, 5 and 13 levels. This suppression of allergic T helper 2 parameters was maintained through 13 weekly ragweed exposures administered after treatment cessation. Subsequent experiments demonstrated that at least five treatments were required for lasting suppression. Although CpG-ODN induced moderate T helper 1 responses, suppression of allergic airway disease did not require interferon γ but was associated with induction of a regulatory T-cell response.

CONCLUSIONS

A short series of CpG-ODN treatments results in sustained suppression of allergic lung inflammation induced by a clinically relevant allergen.

Subcutaneous immunotherapy for allergic rhinitis: an evidence based review of the recent literature with recommendations

BACKGROUND

Allergic rhinitis is a common allergic disease with increasing prevalence in Western Societies. Medical therapy is first line treatment, and is aimed at reducing symptoms of immunoglobulin E (IgE)-mediated inflammation of the nasal passages. In patients with disease refractory to medical therapy, subcutaneous immunotherapy is an option. The aim of this study is to update a recent Cochrane review with available level 1 evidence for seasonal and perennial allergic rhinitis.

METHODS

A systematic review of the literature was performed from 2006 to 2011 and compared with data from a 2007 Cochrane review on immunotherapy for seasonal allergic rhinitis. We included all studies of level 1 evidence. All forms of single extract immunotherapy were considered. Studies with primary asthma related end-points were excluded. Primary end-points were instruments of clinical efficacy (ie, symptom-medication scores) and adverse events.

RESULTS

We retrieved 12 level 1 studies for review. In total, 1512 patients were randomized into treatment groups, alternative study groups (alternative duration of therapy or sublingual immunotherapy [SLIT]), or placebo. Efficacy was evaluated based on reported symptom and/or medication score, validated quality of life instruments, immunological assays, challenge testing, and adverse events.

CONCLUSION

Subcutaneous immunotherapy improves symptom and/or medication scores and validated quality of life measures. In addition, associated changes in surrogate markers of immunologic protection are observed. Subcutaneous immunotherapy is safe when administered to carefully selected patients and in settings capable of responding to systemic reactions. Subcutaneous immunotherapy is recommended for patients with seasonal or perennial allergic rhinitis not responsive to conservative medical therapy, and whose symptoms significantly affect quality of life.

Factors affecting time required to reach maintenance dose during subcutaneous immunotherapy

BACKGROUND

Subcutaneous immunotherapy (SCIT) demands a significant time commitment on the part of the patient, especially during the escalation period when weekly visits are required. Many patients refuse or discontinue treatment in spite of the demonstrated clinical efficacy of SCIT. Understanding the factors that affect the length of the escalation phase would allow for counseling of patients, which may improve patient compliance. The aims of this study were to determine the mean time required to reach maintenance dose during conventional protocol SCIT and to identify factors that significantly affect the time required to reach maintenance dose.

METHODS

We conducted a retrospective chart review of 55 patients (total of 79 treatment vials) who began SCIT between January 2007 and December 2010 and reached maintenance dose. The effect of demographic data, medical and social history, and SCIT allergen data on the time required to reach maintenance dose were examined using bivariate and multivariate analyses.

RESULTS

The mean time to maintenance dose for the 79 treatment vials was 240.2 days (range, 76-720 days). Males (mean 294.7 days) took significantly longer than females (mean 205.1 days) to reach maintenance dose (p = 0.007). Asthmatics (mean 285.5 days) took significantly longer than nonasthmatics (mean 218.0 days) to reach maintenance dose (p = 0.008). Age also significantly affected the length of the escalation phase; each additional year of age was associated with an increase in 3.9 days needed to reach maintenance dose (p = 0.002).

CONCLUSION

Gender, asthma, and age significantly impact the time required to reach maintenance dose during SCIT.

Systemic reactions to subcutaneous allergen immunotherapy

Subcutaneous allergen immunotherapy (SCIT) has been practiced for 100 years. Many trials have established the efficacy of SCIT in reducing symptoms of both seasonal allergic rhinitis and asthma due to aeroallergens. However, clinical benefits of SCIT are tempered by risks of injection-related systemic reactions and life-threatening anaphylaxis. This article reviews data derived from retrospective surveys conducted to define the incidence, prevalence, and factors contributing to injection-related fatal anaphylactic and near-fatal systemic reactions, as well as recently initiated longitudinal surveillance studies of SCIT reactions.

Registration trials for specific immunotherapy in Europe: advanced guidance from the new European Medical Agency guideline

Marketing authorization of medicinal products is granted based on results of registration trials. The European Medical Agency (EMA) has issued general and disease state-specific guidelines for the conduct of such trials. In the area of allergic diseases, there are basically two general therapeutic approaches: Drugs that mitigate the symptoms and an approach that is targeted to the root cause of the disease, the allergen-specific immunotherapy (SIT). While the 'Guideline on the Clinical Development of Medicinal Products for the Treatment of Allergic Rhino-Conjunctivitis' (CHMP/EWP/2455/02) and the 'Note for Guidance on the Clinical Investigation of Medicinal Products in the Treatment of Asthma' (CPMP/EWP/2922/01) focuses exclusively on the development of medicinal products to treat allergic symptoms, there was no guideline for SIT in the past. In consequence, the conduct of clinical trials for SIT was widely lacking a standardized approach. This created difficulties when comparing drugs and outcomes and also uncertainty to predict marketing authorization. In 2009, the EMA has issued a new guideline on the clinical development of products for SIT. Despite some white spots in some areas, the new guideline constitutes a breakthrough with regard to guidance, harmonization and transparency in the conduct of clinical trials in SIT.

The diagnosis and management of anaphylaxis practice parameter: 2010 update

These parameters were developed by the Joint Task Force on Practice Parameters, representing the American Academy of Allergy, Asthma & Immunology (AAAAI); the American College of Allergy, Asthma & Immunology (ACAAI); and the Joint Council of Allergy, Asthma and Immunology. The AAAAI and the ACAAI have jointly accepted responsibility for establishing "The Diagnosis and Management of Anaphylaxis Practice Parameter: 2010 Update." This is a complete and comprehensive document at the current time. The medical environment is a changing environment, and not all recommendations will be appropriate for all patients. Because this document incorporated the efforts of many participants, no single individual, including those who served on the Joint Task Force, is authorized to provide an official AAAAI or ACAAI interpretation of these practice parameters. Any request for information about or an interpretation of these practice parameters by the AAAAI or ACAAI should be directed to the Executive Offices of the AAAAI, the ACAAI, or the Joint Council of Allergy, Asthma and Immunology. These parameters are not designed for use by pharmaceutical companies in drug promotion.

A review of allergen-specific immunotherapy in human and veterinary medicine

This article reviews allergen-specific immunotherapy in human and veterinary medicine. Current hypotheses of possible mechanisms of actions are outlined. Indications, success rates, adverse effects and factors influencing outcome of therapy are discussed in humans, dogs, cats and horses.

Multiallergen immunotherapy for allergic rhinitis and asthma

The English and non-English language literature on allergen immunotherapy was reviewed for studies simultaneously using 2 or more distinct allergen extracts in either subcutaneous or sublingual immunotherapy. Thirteen studies were identified, 11 using subcutaneous injections, 1 using sublingual administration, and 1 using both. In studies with adequate information, administration of 2 extracts by means of either subcutaneous immunotherapy or sublingual immunotherapy was effective. In studies using multiple allergens, 3 studies showed clear efficacy, whereas in the other 2 studies, lack of efficacy might have been due to inadequate doses of extract or omission of clinically relevant allergens in the treatment regimen. It is concluded that simultaneous administration of more than 1 allergen extract is clinically effective. However, more studies are needed, particularly with more than 2 allergen extracts and with sublingual administration.

Allergen-related approaches to immunotherapy

Allergic diseases, including asthma, rhinitis and eczema, represent a major health burden worldwide. Mainstay treatments are allergen avoidance where feasible and pharmacotherapy for symptom relief. For selected patients, allergen-specific immunotherapy (SIT) offers the prospect of long lasting clinical efficacy. SIT involves the administration of allergen extract using a standardized regimen, usually subcutaneously or increasingly sublingually. However, application of this potentially curative treatment is restricted, largely due to the risk of serious adverse events, especially in asthmatics and for potent allergens such as peanut, seafood and latex. New insights into immunological mechanisms underlying effective SIT and molecular characterization of allergens and their recognition by the immune system suggest strategies for refinement of SIT. Selective targeting of allergen-specific T cells, especially regulatory T cells, is likely to be pivotal for efficacy. Recombinant allergens lacking IgE reactivity and small T cell epitope-based peptides are being trialled clinically with evidence of efficacy without serious IgE-mediated adverse reactions. Adjuvants, either co-administered or incorporated into a recombinant allergen vaccine to target tolerogenic dendritic cells may also increase efficacy. The safer sublingual route of allergen administration is attracting interest and different allergen forms may be optimal for inducing tolerance by this route. Defined allergen-derived molecules or peptides offer ease of standardization and, coupled with appropriate targeting of immunoregulatory mechanisms, will result in more widespread clinical use of SIT. Adjunct therapies such as anti-IgE antibody and corticosteroids may minimize the likelihood of adverse reactions in those with severe allergic disease who would most benefit from this treatment.

BSACI guidelines for the management of allergic and non-allergic rhinitis

This guidance for the management of patients with allergic and non-allergic rhinitis has been prepared by the Standards of Care Committee (SOCC) of the British Society for Allergy and Clinical Immunology (BSACI). The guideline is based on evidence as well as on expert opinion and is for use by both adult physicians and paediatricians practicing in allergy. The recommendations are evidence graded. During the development of these guidelines, all BSACI members were included in the consultation process using a web-based system. Their comments and suggestions were carefully considered by the SOCC. Where evidence was lacking, consensus was reached by the experts on the committee. Included in this guideline are clinical classification of rhinitis, aetiology, diagnosis, investigations and management including subcutaneous and sublingual immunotherapy. There are also special sections for children, co-morbid associations and pregnancy. Finally, we have made recommendations for potential areas of future research.

Anaphylactic reactions during immunotherapy

Subcutaneous immunotherapy (IT) with aeroallergen extracts is venerable treatment modality. The major risk associated with IT with commercial aeroallergen extracts is the uncommon occurrence of severe near-fatal or fatal anaphylaxis after injections. The objectives of this article are to review the reported incidences of severe anaphylaxis (near-fatal reactions and fatal reactions), define factors contributing to these events, and identify preventive measures that are likely to reduce or eliminate future fatal and near-fatal anaphylactic events. As with any treatment, anticipated benefits attributed to IT must be weighed against its potential risks.

Allergen injection immunotherapy for seasonal allergic rhinitis

BACKGROUND

Allergic rhinitis is the most common of the allergic diseases. Despite improved understanding of the pathophysiology of allergic rhinitis and advances in its pharmacological treatment, its prevalence has increased worldwide. For patients whose symptoms remain uncontrolled despite medical treatment, allergen injection immunotherapy is advised. An allergen-based treatment may reduce symptoms, the need for medication and modify the natural course of this disease.

OBJECTIVES

To evaluate the efficacy and safety of subcutaneous specific allergen immunotherapy, compared with placebo, for reducing symptoms and medication requirements in seasonal allergic rhinitis patients.

SEARCH STRATEGY

We searched the Cochrane Ear, Nose and Throat Disorders Group Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 1 2006), MEDLINE (1950 to 2006), EMBASE (1974 to 2006), Pre-MEDLINE, KOREAMED, INDMED, LILACS, PAKMEDINET, Scisearch, mRCT and the National Research Register. The date of the last search was February 2006.

SELECTION CRITERIA

All studies identified by the searches were assessed to identify randomised controlled trials involving participants with symptoms of seasonal allergic rhinitis and proven allergen sensitivity, treated with subcutaneous allergen specific immunotherapy or corresponding placebo.

DATA COLLECTION AND ANALYSIS

Two independent authors identified all studies reporting double-blind, placebo controlled randomised trials of specific immunotherapy in patients with seasonal allergic rhinitis due to tree, grass or weed pollens. Two authors independently performed quality assessment of studies. Data from identified studies were abstracted onto a standard extraction sheet and subsequently entered into RevMan 4.2.8. Analysis was performed using the Standardised Mean Difference (SMD) method and a random-effects model; P values < 0.05 were considered statistically significant. The primary outcome measures were symptom scores, medication use, quality of life and adverse events.

MAIN RESULTS

We retrieved 1111 publications of which 51 satisfied our inclusion criteria. In total there were 2871 participants (1645 active, 1226 placebo), each receiving on average 18 injections. Duration of immunotherapy varied from three days to three years. Symptom score data from 15 trials were suitable for meta-analysis and showed an overall reduction in the immunotherapy group (SMD -0.73 (95% CI -0.97 to -0.50, P < 0.00001)). Medication score data from 13 trials showed an overall reduction in the immunotherapy group (SMD of -0.57 (95% CI -0.82 to -0.33, p<0.00001)). Clinical interpretation of the effect size is difficult. Adrenaline was given in 0.13% (19 of 14085 injections) of those on active treatment and in 0.01% (1 of 8278 injections) of the placebo group for treatment of adverse events. There were no fatalities.

AUTHORS' CONCLUSIONS

This review has shown that specific allergen injection immunotherapy in suitably selected patients with seasonal allergic rhinitis results in a significant reduction in symptom scores and medication use. Injection immunotherapy has a known and relatively low risk of severe adverse events. We found no long-term consequences from adverse events.

Biological assay using T cell response for Cry-consensus peptide designed for the peptide-based immunotherapy of Japanese cedar pollinosis

INTRODUCTION

Cry-consensus peptide is a linearly linked peptide of T-cell epitopes for the management of Japanese cedar (JC) pollinosis and is expected to become a new drug for immunotherapy. However, the mechanism of T-cell epitopes in allergic diseases is not well understood, and thus, a simple in vitro procedure for evaluation of its biological activity is desired.

METHODS

Peripheral blood mononuclear cells (PBMC) were isolated from 27 JC pollinosis patients and 10 healthy subjects, and cultured in vitro for 4 days in the presence of Cry-consensus peptide and (3)H-thymidine. The relationship between growth stimulation (stimulation index; SI) and antigen-specific IgE levels in serum was also investigated in JC pollinosis patients. Moreover, to confirm the importance of the primary sequence in Cry-consensus peptide, heat-treated Cry-consensus peptide and a mixture of the amino acids of which Cry-consensus peptide is composed, and their (3)H-thymidine uptake was compared with Cry-consensus peptide. Finally, whether Cry-consensus peptide stimulates PBMCs from healthy subjects was investigated.

RESULTS

The mean SI of JC patients showed a good correlation with Cry-consensus peptide concentration in the culture medium; however, the SI was independent of the anti-Cry j 1 IgE level. Heat-denatured Cry-consensus peptide retained a PBMC proliferation stimulatory effect comparable to the original Cry-consensus peptide, while the mixture of amino acids constituting Cry-consensus peptide did not stimulate PBMC proliferation. PBMCs from healthy subjects did not respond to Cry-consensus peptide at all.

DISCUSSION

These data indicate that the PBMC response of patients suffering from JC pollinosis to Cry-consensus peptide is specific for the sequence of T cell epitopes thereof and may be useful for the evaluation of the efficacy of Cry-consensus peptide in vivo.

Efficacy and safety of allergen immunotherapy in children

OBJECTIVE

To determine the efficacy and safety of immunotherapy in children with allergic rhinitis and allergic asthma.

DATA SOURCES

Current Contents database for 1967 to 2005.

STUDY SELECTION

The expert opinion of the author was used to select studies for inclusion in this review.

RESULTS

Meta-analyses have confirmed the clinical effectiveness of allergen immunotherapy in patients with allergic rhinitis and asthma; however, most studies involved immunotherapy with a single allergen. Special considerations of safety regarding immunotherapy in children are also necessary, since fatalities have been reported. Fatal reactions occur primarily in patients with asthma and particularly those whose asthma is not well controlled. There is probably increased risk during the build-up phase and with the first injection from a new vial. Injections at home or in clinics without adequate supervision also constitute an increased risk of a fatal outcome.

CONCLUSIONS

Specific immunotherapy has been demonstrated to have some protective effect against the development of additional sensitivities in the monosensitized child and to reduce the risk of developing asthma in children with allergic rhinitis. Because of the modification of the underlying immune process, the beneficial effects of immunotherapy persist for a long but not yet fully determined period after the cessation of treatment. This persisting effect makes immunotherapy an attractive supplement to symptomatic treatment of children with allergic asthma and allergic rhinitis. The treatment is not without risk, however, especially in the child with asthma, so it should be administered with caution.

Sublingual immunotherapy abrogates seasonal bronchial hyperresponsiveness in children with Parietaria-induced respiratory allergy: a randomized controlled trial

BACKGROUND

The use of immunotherapy in asthmatic children is still controversial. Sublingual immunotherapy (SLIT) may represent an advance, due to the good safety profile, but little is known about its effects on lung function and nonspecific bronchial responsiveness.

OBJECTIVE

The aim of this study was to assess the effects of SLIT on these parameters, in children with Parietaria pollen-induced asthma.

METHODS

Thirty children with asthma solely due to Parietaria who participated in a previous randomized, placebo-controlled trial with SLIT were studied: pulmonary function test and methacholine challenge were carried out at baseline in winter 1999 (out season), during the 1999 season (before randomization), and during the 2001 season.

RESULTS

Before randomization, there was a significant fall in methacholine provocation concentration during the pollen season vs baseline in both groups (SLIT group 9.78 +/- 5.95 mg/ml vs 3.37 +/- 2.99 mg/ml; placebo 8.70 +/- 6.25 mg/ml vs 2.44 +/- 2.25 mg/ml; P =.005). In the second pollen season, the response to methacholine returned to baseline values in the active group (9.10 +/- 7.7 mg/ml; P = NS vs baseline), whereas in the placebo group a significant increase in reactivity was still present (2.46 +/- 2.26; P = 0.008 vs baseline). No significant difference in FEV(1) and FEF(25-75) between the two groups was observed at all times.

CONCLUSIONS

Our data show that SLIT abrogates the seasonal bronchial hyperreactivity in children with asthma due to Parietaria. This may be regarded as an indirect evidence of the effect on bronchial inflammation.

Clinical and immunologic changes after allergen immunotherapy with Hop Japanese pollen

BACKGROUND AND OBJECTIVE

Hop Japanese (Hop J) pollen has been reported as one of the major causative pollen allergens in the autumn season. There have been no published data regarding the clinical and immunologic effects of Hop J pollen immunotherapy in sensitized patients. In this study, we evaluated clinical and immunologic effects of Hop J immunotherapy.

PATIENTS AND METHODS

Pollens were collected in our area, and "Depo-Hop J" was prepared in the laboratory of Allergopharma (Reinbek, Germany). Fifteen asthmatic patients who had Hop J immunotherapy for > 1 year were enrolled. Their clinical parameters, such as asthma symptom scores, were monitored. Skin reactivity to Hop J and degree of airway hyperresponsiveness to methacholine were measured before and 1 year after the immunotherapy. Sera were collected before the immunotherapy, at the end of initial therapy, and 1 year after the therapy. Serum total IgE levels were compared by radioimmunoassay. Serum-specific IgE, IgG1, and IgG4 levels to Hop J were compared by ELISA. To evaluate the changes of cellular mechanisms, soluble CD30 (sCD30), soluble interleukin (IL)-2 receptor (sIL-2R), soluble CD23 (sCD23), and IL-10 levels were measured by ELISA.

RESULTS

Specific IgG1 and IgG4 levels began to increase at the end of the initial therapy (P < 0.05) with significant decreases in symptom scores (P < 0.05), whereas total and specific IgE levels showed variable responses during the immunotherapy with no statistical significance (P > 0.05). Serum sIL-2R and sCD30 levels decreased significantly (P < 0.05) 1 year after immunotherapy. No significant changes were noted in sCD23, IL-10, skin reactivity to Hop J, or airway responsiveness to methacholine (P > 0.05).

CONCLUSIONS

We are certain that Hop J allergen immunotherapy, if carried out properly according to suitable indications, can favorably influence asthma. Thus, an increase in specific IgG4 and IgG1 antibodies and reduction of a possible Th2 lymphocyte marker (sCD30) may be associated with symptomatic improvements.

Evaluation of the wheezy infant

BACKGROUND

The infant with persistent or recurrent wheezing during the first 2 years of life poses a diagnostic dilemma, which can be a source of anxiety to both physicians and parents. A suggested diagnostic approach to the causes of infantile wheezing is outlined.

OBJECTIVES

1. To review the physiologic considerations of the infant's airways that predispose to wheezing. 2. To discuss the key physical findings, family history, and risk factors associated with wheezing in infants. 3. To develop a rational approach to the differential diagnosis and management of infantile wheezing.

DATA SOURCES

The MEDLINE database as well as our clinical experience pertaining to infantile wheezing.

CONCLUSIONS

This review discusses the diagnostic evaluation and treatment of the wheezing infant. We suggest that infant pulmonary function testing may be used as one diagnostic aid in the workup of the wheezing infant.

Allergen immunotherapy: current and new therapeutic strategies

Allergic individuals respond to an environmental allergen encounter by producing T-cell cytokines, predominantly IL-4 and IL-5, which in turn drive the production of allergen-specific IgE antibodies and recruitment of an eosinophil-rich inflammatory infiltrate. Allergen-specific immunotherapy (SIT) involves the repeated injection of the allergen to specifically downregulate this predominantly Th2-type immune response. SIT is a clinically proven effective treatment for allergic diseases, including rhinoconjunctivitis and asthma. However, despite having been in clinical practice since early this century, its use remains empirical. Best practice protocols are based on clinical experience and include recommendations for selecting patients for treatment, SIT regimes and avoidance of adverse events. More rational and safer SIT regimes will result from new insights into the underlying immune mechanisms for allergic disease, in particular the critical role of helper T-cells in orchestrating this response. The development of recombinant techniques for producing purified allergens and allergen derivatives has led to a dramatic improvement in the ability to standardise allergen preparations and to develop novel vaccines for allergy treatment. Potential vaccines include short peptides based on dominant T-cell epitopes of allergens, allergen fragments and mutant allergens. All of these preparations are designed to target T-cells without binding IgE and inducing local and systemic side effects. Additional strategies under consideration include DNA vaccines and fusion protein constructs incorporating immunomodulatory elements such as bacterial cell proteins, cytokines and immunostimulatory sequences of DNA. Different forms of allergens are being evaluated for the more practical mucosal administration of allergy vaccines. The identification of recombinant allergens suitable for diagnostic use and the development of reliable laboratory assays, based on T-cell function to monitor clinical efficacy of SIT, are important practical outcomes from this research.

Immunologic changes associated with allergen immunotherapy

Specific allergen injection immunotherapy is highly effective in selected patients with IgE-mediated disease, including respiratory allergy and venom anaphylaxis. Research in this area provides insight into the immunologic basis of allergic disease and may assist in the development of more highly targeted treatment. Immunotherapy reduces immediate allergen-induced symptoms and concentrations of inflammatory mediators, including histamine and prostaglandin D2, in ragweed-sensitive patients. Similarly, nasal epithelial mast cell numbers are decreased. A characteristic feature of immunotherapy is its ability to inhibit late-phase responses. In the nose it is accompanied by a decrease in eosinophil numbers in lavage during late responses. Characteristic changes in serum immunoglobulins are found, with an initial increase in IgE followed by a blunting of seasonal increases in IgE in pollen-sensitive patients and a gradual decline in allergen-specific IgE levels over several years. This is accompanied by an increase in allergen-specific IgG (blocking antibodies), although neither appear to correlate closely with the clinical response to immunotherapy. One way in which immunotherapy may act is by modifying the T-lymphocyte response to subsequent natural allergen exposure. Studies in peripheral blood and within the target organ have demonstrated a shift in the balance of T-cell subsets away from TH2-type (producing particularly IL-4 and IL-5) in favor of a TH1-type T-lymphocyte response (with the preferential production of IFN-gamma). Studies of the nasal mucosa before and after immunotherapy have demonstrated suppression of the late nasal response and increases in the numbers of cells expressing mRNA for IFN-gamma. It is not clear whether this immune deviation is due to anergy of TH2/TH0 cells or increases in TH0/TH1 T-lymphocyte responses. An alternative may be amplification of suppressor CD8+ T cells, which may have a downregulatory effect. Novel approaches currently being explored include the use of T-cell reactive peptides, which might circumvent the risk of anaphylaxis, and the use of adjuvants such as IL-12 or mycobacterial vaccines to potentiate the effects of allergen in inducing immune deviation.

Allergic rhinitis. Outcomes of immunotherapy on symptom control

Recent scientific studies have demonstrated the efficacy of various forms of immunotherapy for the treatment of allergic diseases. Traditional subcutaneous immunotherapy, sublingual, oral, and intranasal immunotherapy have been shown to significantly reduce symptoms and favorably modulate the immune response. Outcome studies that use patient response data from standardized surveys represent the next challenge to all practicing allergists.

Safe allergen immunotherapy. The correct allergen, the appropriate patient, the adequate dose

Effective immunotherapy has been shown to be allergen-specific, dose-dependent, and duration-dependent. Patients must receive adequate doses of the relevant allergen to obtain benefit, and most require 3 to 5 years of injections to maintain prolonged benefit after injections are stopped. Concurrently, patients must cooperate by modifying their environment and using some medications during difficult seasons. Although serious reactions to immunotherapy are relatively rare, a physician must be readily available whenever injections are administered, and office staff need to recognize and be ready to respond to systemic reactions.

Immunotherapy basics

Immunotherapy is the use of controlled exposure to allergens to produce durable antiinflammatory effects, thus reducing the severity of allergic disorders. Immunotherapy is useful when other methods of allergy therapy are not fully satisfactory and can be effectively combined with rhinologic surgical treatment. Immunotherapy should always be considered as a treatment option for allergy patients and can often be of benefit, provided that appropriate indications and contraindications are observed. Physicians caring for patients with allergies should therefore become familiar with methods of allergy and diagnosis and with the therapeutic potential of immunotherapy. The history of immunotherapy, possible mechanisms, indications, contraindications, testing methods, and initiation of treatment are reviewed.

The incidence and nature of adverse reactions to injection immunotherapy in bee and wasp venom allergy

The incidence, time course and nature of systemic reactions to injections of bee and wasp venom during immunotherapy have been estimated in an open, prospective, single centre study. One hundred and nine survivors of moderate to severe systemic reactions to stings from hymenoptera, received courses of bee or wasp venom by monthly subcutaneous injection for up to 3 years. Systemic reactions were recorded after 7.5% of 946 weekly venom injections during the initial phase of treatment, and after 2.1% of 1789 monthly maintenance injections. In both phases of treatment, reactions were more frequent after bee (17% of initial phase, 7.8% of maintenance treatment) than after wasp (3% of initial phase, 0.3% of maintenance treatment) venom injections. The percentage of patients experiencing at least one reaction was also higher for bee (46%) than for wasp (14%) sensitive patients. Over 80% of reactions began within 30 min of injection, over 90% within 1 h and only two (2%), between 1 and 2 h, the remaining six (5.5%) starting more than 2 h after injection. Only 0.47% of venom injections produced a systemic reaction which was severe enough to require adrenaline treatment. The female patients experienced more reactions (21% of the wasp, 60% of the bee, sensitive) than the males (5.5% wasp, 20% bee). Age and atopy did not appear to be significant risk factors for systemic reactions. We conclude that wasp and bee venom immunotherapy in a conventional dosage regimen was generally well tolerated.(ABSTRACT TRUNCATED AT 250 WORDS)

Mapping of T cell epitopes of the major fraction of rye grass using peripheral blood mononuclear cells from atopics and non-atopics. II. Isoallergen clone 5A of Lolium perenne group I (Lol p I)

Rye grass is the major cause of hay fever which currently affects 20% of the population. Lolium perenne group I (Lol p I) is a glycoprotein of 240 amino acid residues, representing the main allergen of rye grass. We have used peripheral blood mononuclear cells (PBMC) from controls and subjects allergic to rye grass and cultured them with L. perenne extract (LPE) and Lol p I and measured lymphocyte activation using thymidine incorporation. Patients were further studied against the 115 overlapping peptides of the iso-allergen clone 5A of Lol p I to see whether the 4 amino acid residue differences between clone 1A and clone 5A affect the T cell epitope and thus, lymphocyte activation. There are 24 peptide differences between isoallergen clone 1A and clone 5A occurring in pools 4, 13, 16 and 19 each one of which could be an immunodominant epitope. The PBMC from all allergic patients studied showed a strong proliferative response to LPE and Lol p I. Five immunogenic peptide pools, pool 6, 15, 16, 17 and 19 of the isoallergen clone 5A were also identified. Most of these pools are in the C-terminal region of Lol p I. Out of 20 pools tested in vitro 1 pool (pool-17) induced PBMC proliferation in five out of six patients who were not restricted to an HLA class II DR gene product. However, three out of the six subjects responded to various other peptide pools in addition to the immunodominant pool. In spite of the amino acid differences between the two clones, pool 17 still remains the immunodominant T cell epitope. Control subjects showed only weak responses to LPE and no detectable response to either Lol p I or peptide pools. From within the most active pool we have defined two peptides of the isoallergen clone 5A (identical in sequence with clone 1A) which stimulate lymphocytes from rye grass-sensitive patients in vitro. Previous studies with the two continuous sequences (193WGAVWRIDTPDK204 and 195AVWRIDTPDKLT206) tested in vivo by intradermal skin testing have shown typical delayed-type hypersensitivity reactions after 24-48 h in one patient. Comparison of amino acid sequences of Lol p I, Lol p II and Lol p III proteins revealed a significant level of structural similarity among them. Interestingly, 50% of the residues of the second peptide sequence are also present in Lol p II and Lol p III.(ABSTRACT TRUNCATED AT 400 WORDS)