Grass pollen sublingual immunotherapy for seasonal rhinoconjunctivitis: a randomized controlled trial

Sublingual immunotherapy for hazelnut food allergy: a randomized, double-blind, placebo-controlled study with a standardized hazelnut extract

BACKGROUND

Food allergy may be life-threatening, and patients affected need to receive accurate diagnoses and treatment. Hazelnut has often been implicated as responsible for allergic reactions, and trace quantities can induce systemic reactions.

OBJECTIVE

The aim of this study was to evaluate the efficacy and tolerance of sublingual immunotherapy with a standardized hazelnut extract in patients allergic to hazelnut.

METHODS

This was a randomized, double-blind, placebo-controlled study. Inclusion criteria were a history of hazelnut allergy and positive skin prick test and double-blind placebo-controlled food challenge results. Patients were then randomly assigned into 2 treatment groups (hazelnut immunotherapy or placebo). Efficacy was assessed by double-blind, placebo-controlled food challenge after 8 to 12 weeks of treatment. Blood samples were drawn for measurement of specific IgE, IgG(4), and serum cytokines before and after treatment.

RESULTS

Twenty-three patients were enrolled and divided into 2 treatment groups. Twenty-two patients reached the planned maximum dose at 4 days. Systemic reactions were observed in only 0.2% of the total doses administered. Mean hazelnut quantity provoking objective symptoms increased from 2.29 g to 11.56 g (P = .02; active group) versus 3.49 g to 4.14 g (placebo; NS). Moreover, almost 50% of patients who underwent active treatment reached the highest dose (20 g), but only 9% in the placebo. Laboratory data showed an increase in IgG(4) and IL-10 levels after immunotherapy in only the active group.

CONCLUSION

Our data confirm significant increases in tolerance to hazelnut after sublingual immunotherapy as assessed by double-blind, placebo-controlled food challenge, and good tolerance to this treatment.

The safety of sublingual-swallow immunotherapy: an analysis of published studies

BACKGROUND

As the main target of sublingual immunotherapy (SLIT) is to reduce at most the occurrence of adverse events (AE), safety represents a critical issue. This aspect deserves particular mention when a higher dose of allergen extract than traditional subcutaneous immunotherapy (SCIT) is required to be effective: that may be up to 500 times that employed for SCIT.

OBJECTIVE

All published controlled studies concerning SLIT-swallow were analysed to evaluate AE rates.

METHODS

Studies were subdivided in two groups: (i) studies using low allergen dose (LAD), i.e. ranging from 1 to 50 times the dose commonly administered with SCIT, and (ii) studies with high allergen dose (HAD), i.e. ranging from 50 to 500 times the dose administered with SCIT.

RESULTS

Twenty-five studies were altogether analysed: 13 studies belonged to the low-dose group, 12 belonged to the high-dose group. We considered all patients with at least one AE. Local reactions were significantly more frequent in the LAD group than in the HAD group (P<0.0001), while there was no difference in the rate of systemic reactions. Severe systemic reactions were never reported.

CONCLUSION

This study represents the first analysis of the safety of SLIT concerning the allergen dose employed in the treatment. There is evidence that AE occurrence is substantially not dose-dependent. This fact highlights two main clinical aspects: the elevated tolerability of SLIT in general and the safety of HAD regimen.

Induction of interleukin 10 by sublingual immunotherapy for house dust mites: a preliminary report

BACKGROUND

Subcutaneous specific immunotherapy has been demonstrated to be capable of inducing T-cell regulatory response. Interleukin 10 (IL-10) plays a crucial role in inducing allergen-specific tolerance; however, no previous studies have examined IL-10 production after sublingual immunotherapy (SLIT).

OBJECTIVE

To evaluate T-cell proliferation and IL-10 production in patients successfully treated with SLIT for house dust mites (HDMs).

METHODS

Peripheral blood mononuclear cells were isolated from patients after at least 3 years of successful HDM SLIT and from matched untreated allergic patients and healthy control subjects. After 3 and 6 days of in vitro stimulation with phytohemagglutinin (PHA), Candida albicans, and Dermatophagoides farinae, proliferation and production of IL-10 were measured.

RESULTS

Patients treated with SLIT showed a significant reduction of proliferation induced by C albicans compared with untreated atopic patients (P < .001), but a significant reduction was also demonstrated in healthy controls compared with untreated atopic patients (P < .001). Patients treated with SLIT also showed a significant increase of IL-10 production after Candida and PHA stimuli compared with patients with untreated rhinitis (P < .001 for both). Patients with untreated rhinitis did not produce IL-10.

CONCLUSION

This preliminary study confirms reduced T-cell proliferation and preliminarily provides the first evidence, to our knowledge, of peripheral IL-10 production in allergic patients successfully treated with HDM SLIT.

Three-year follow-up of clinical and inflammation parameters in children monosensitized to mites undergoing sub-lingual immunotherapy

Parallel follow-up of clinical and inflammatory markers during sub-lingual immunotherapy (SLIT) is highly beneficial. Twenty-four children (age 4-16) monosensitized to house dust mite were randomized to receive either active or placebo SLIT for 1 yr in a double-blind placebo controlled design (Marcucci et al., Allergy 2003: 58: 657-62). Thereafter, for 2 yr they all received active treatment. Symptom scores for rhinitis, asthma, and drug usage were daily recorded. Eosinophil cationic protein (ECP) and tryptase in sputum and nasal secretions, serum and nasal mite-specific immunoglobulin E (IgE) were recorded before treatment and at 10-12 months intervals. Nasal ECP and nasal tryptase after specific nasal provocation tests were significantly reduced as compared to baseline values (p = 0.0043 and 0.0195, respectively) in the third year of active treatment. None of the other inflammatory parameters was increased. In placebo treated patients all these parameters tended to decrease only after switching to active treatment. Clinical scores did not improve in treated vs. placebo patients in the double-blind placebo-controlled phase of the study. In both cohorts a clinical benefit was observed as intra-group score reduction as compared to baseline. A significant difference was reached in patients treated for 2 yr for rhinitis and asthma (p = 0.0009 and 0.0019, respectively) but not for drug usage and in patients treated for 3 yr for rhinitis, asthma, and drug usage (p = 0.0105, 0.0048, and 0.02, respectively). SLIT in children monosensitized to mites reverted the spontaneous increase in nasal IgE and in local parameters of allergic inflammation. These outcomes were followed by a consolidated clinical improvement in the second and third year of treatment.

Dose dependence of immunological response to sublingual immunotherapy

BACKGROUND

Sublingual-swallow immunotherapy (SLIT) is an accepted treatment for allergic rhinitis but its optimal dosage is scantly investigated. We studied the dose dependence of clinical efficacy and immunological response to SLIT by administering two different dosages of the same allergen in rhinitic children monosensitized to grass pollen.

METHODS

Seventy-one patients with comparable age and symptoms were randomized to receive SLIT by the same grass pollen extract from Stallergenes (Antony, France), 40 of them with the 100 IR and 31 with the 300 IR extract. All patients recorded diary cards for symptoms, medications and side-effects of the treatment, and had measurements of specific IgE and IgG4 in serum by the CAP System FEIA (Pharmacia, Uppsala, Sweden) and in nasal secretion by an in situ incubation method with the same reagents of CAP System FEIA.

RESULTS

Symptom/medication scores during the pollen season were significantly higher in patients treated with the lower dosage compared with those treated with the 300 IR dosage. Side-effects occurred with a comparable rate (25.8%vs 27.5%) in the two groups. Serum-specific IgE and IgG4 had no significant changes after 3 months of SLIT in both groups, while a significant seasonal increase of nasal IgE (P = 0.015) and IgG4 (P = 0.019) was found only in patients treated with the lower dosage.

CONCLUSIONS

A rise of specific IgG4 and a blunting of seasonal increase of specific IgE in serum was repeatedly reported during subcutaneous immunotherapy (SCIT) with pollen extracts. Our findings show such blunting of specific nasal IgE along with a low symptom/medication score in patients treated with SLIT with the higher dosage, but not a concomitant rise of specific nasal IgG4. This suggests a local immunological effect of SLIT, different from systemic mechanisms of SCIT.

Lack of detectable alterations in immune responses during sublingual immunotherapy in children with seasonal allergic rhinoconjunctivitis to grass pollen

BACKGROUND

Recent work indicates that subcutaneous specific immunotherapy induces specific T-cell anergy, a shift in the TH1/TH2 ratio, and antibody production in favor of IgG4. There are few data on sublingual immunotherapy (SLIT), especially in children.

METHODS

We assessed the proliferation of peripheral blood mononuclear cells ((3)H-thymidine incorporation) and secretion of interleukin (IL)-4, interferon (IFN)gamma and IL-5 (ELISA) after in vitro stimulation with allergen or phytohemagglutinin (PHA) in 29 children with allergic rhinoconjunctivitis receiving SLIT with grass pollen before, and after 1 and 2 years of treatment in a multicenter placebo-controlled study on the efficacy of the treatment. Further, non-specific intracellular production of IL-4, IL-13, IFNgamma, IL-2, IL-10 and IL-5 (FACS) and serum total and specific IgE and IgG4 (ELISA) were analyzed.

RESULTS

Proliferation and IL-4 and IL-5 secretion after stimulation with allergen or PHA did not differ between the groups. In addition, we observed no effect of SLIT on intracellular cytokine production. IFNgamma secretion after allergen coculture was comparable between the groups. Following PHA stimulation, IFNgamma secretion was significantly higher in the SLIT group after 1 year, and a trend was observable already before and after 2 years of treatment, probably due to the inhomogeneity in the groups despite randomization (for age and asthma). No significant changes were observed for sIgE/sIgG4 ratios over time either in or between the groups.

CONCLUSION

During 2 years of SLIT in children with a positive effect on rescue medication use, we observed no significant effects on in vitro T-cell immune responses or immunoglobulins. So far, pediatric studies demonstrating stable effects of SLIT on such reactions are missing, probably due to limited effects of SLIT on systemic immunologic reactions.

Sublingual immunotherapy for allergic rhinitis: systematic review and meta-analysis

Allergic rhinitis is a common condition which, at its most severe, can significantly impair quality of life despite optimal treatment with antihistamines and topical nasal corticosteroids. Allergen injection immunotherapy significantly reduces symptoms and medication requirements in allergic rhinitis but its use is limited by the possibility of severe systemic reactions. There has therefore been considerable interest in alternative routes for delivery of allergen immunotherapy, particularly the sublingual route. The objective was to evaluate the efficacy of sublingual immunotherapy (SLIT), compared with placebo, for reductions in symptoms and medication requirements. The Cochrane Controlled Clinical Trials Register, MEDLINE (1966-2002), EMBASE (1974-2002) and Scisearch were searched, up to September 2002, using the terms (Rhin* OR hay fever) AND (immunotherap* OR desensiti*ation) AND (sublingual). All studies identified by the searches were assessed by the reviewers to identify Randomized Controlled Trials involving participants with symptoms of allergic rhinitis and proven allergen sensitivity, treated with SLIT or corresponding placebo. Data from identified studies was abstracted onto a standard extraction sheet and subsequently entered into RevMan 4.1. Analysis was performed by the method of standardized mean differences (SMD) using a random effects model. P-values < 0.05 were considered statistically significant. Subgroup analyses were performed according to the type of allergen administered, the age of participants and the duration of treatment. Twenty-two trials involving 979 patients, were included. There were six trials of SLIT for house dust mite allergy, five for grass pollen, five for parietaria, two for olive and one each for, ragweed, cat, tree and cupressus. Five studies enrolled exclusively children. Seventeen studies administered the allergen by sublingual drops subsequently swallowed, three by drops subsequently spat out and two by sublingual tablets. Eight studies involved treatment for less than 6 months, 10 studies for 6-12 months and four studies for greater than 12 months. All included studies were double-blind placebo-controlled trials of parallell group design. Concealment of treatment allocation was considered adequate in all studies and the use of identical placebo preparations was almost universal. There was significant heterogeneity, most likely due to widely differing scoring systems between studies, for most comparisons. Overall there was a significant reduction in both symptoms (SMD -0.42, 95% confidence interval -0.69 to -0.15; P = 0.002) and medication requirements [SMD -0.43 (-0.63, -0.23); P = 0.00003] following immunotherapy. Subgroup analyses failed to identify a disproportionate benefit of treatment according to the allergen administered. There was no significant reduction in symptoms and medication scores in those studies involving only children but total numbers of participants was too small to make this a reliable conclusion. Increasing duration of treatment does not clearly increase efficacy. The total dose of allergen administered may be important but insufficient data was available to analyse this factor.

Sublingual and oral immunotherapy

Sublingual immunotherapy (SLIT) is a viable alternative to the subcutaneous route for the treatment of respiratory allergy, whereas the pure oral route has been abandoned because of its lack of efficacy. The main distinctive feature of SLIT is its optimal safety profile, which has been demonstrated in adults and children. The indications for SLIT are similar to those for the subcutaneous route. A long-lasting effect has been demonstrated for the sublingual route, but data are needed to determine the optimal dose and the preventive effect in asthma.

A prospective, randomized, double-blind, placebo-controlled multi-centre study on the efficacy and safety of sublingual immunotherapy (SLIT) in children with seasonal allergic rhinoconjunctivitis to grass pollen

BACKGROUND

Especially in childhood, sublingual immunotherapy (SLIT) could offer advantages over subcutaneous therapy. However, limited data on its efficacy is available.

METHODS

In four German centres 97 children (age 3-14 years) with allergic rhinoconjunctivitis to grass pollen were enrolled in a prospective, double-blind trial comparing SLIT (Pangramin SLIT; ALK-SCHERAX, 0.5 microg major allergens, three times per week, 32 months) with placebo. Primary endpoint was a multiple symptom-medication score for changes in seasonal diary entries between the first and third year of the study (SLIT n=39; placebo n=38).

RESULTS

The multiple symptom-medication score was significantly reduced by SLIT to 77.3% of the placebo group (P=0.0498). The subsequent analysis of the single endpoints did not reveal significant differences for symptom scores in favour of SLIT (85.1% of placebo group; P=0.22). However, the medication score improved significantly (67.1% of placebo group; P=0.0025). Furthermore, secondary endpoints assessing in vivo immune responses did not differ significantly between the groups. However, retrospective analysis showed some inhomogeneity for clinical and in vitro parameters at the beginning of the study. Allergic side effects with possible relation to the study drug were reported in both groups (SLIT 49%, placebo 27%, P=0.026).

CONCLUSION

Our study indicates that SLIT had a positive effect on the reduction of a multiple symptom-medication score, mainly by significantly reducing rescue medication use, but had no significant effect on symptoms alone in children with rhinoconjunctivitis to grass pollen compared with a placebo.

Sublingual immunotherapy: an update

PURPOSE OF REVIEW

Sublingual immunotherapy is now officially accepted as a viable alternative to the traditional subcutaneous route, and it is widely used especially in European countries. Despite the large amount of experimental evidence on the safety and efficacy of the method, some concerns still exist, and several aspects need to be clarified: magnitude of the efficacy, adherence, long-lasting effect and others. Recently published studies have provided answers to some of these points.

RECENT FINDINGS

The most recent studies have shown that sublingual immunotherapy exerts a long-lasting effect up to 5 years after discontinuation and that it is able to prevent the onset of new sensitizations. Moreover, when systematically assessed, the adherence to treatment is quite satisfactory, despite the treatment being self-administered. In addition, evidence has been provided that sublingual immunotherapy is effective in treating allergic conjunctivitis, and a metaanalysis has confirmed its efficacy in rhinitis. Moreover, some studies have addressed the possibility of simplifying the schedule of administration by shortening the build-up phase.

SUMMARY

More and more new data on sublingual immunotherapy are rapidly appearing in the international literature. These data confirm the clinical value of this treatment and show that it is comparable to subcutaneous immunotherapy from several points of view.

Randomized controlled open study of sublingual immunotherapy for respiratory allergy in real-life: clinical efficacy and more

BACKGROUND

Some aspects of sublingual immunotherapy (SLIT) still need to be addressed: magnitude of the clinical efficacy, effect on the bronchial hyperreactivity adherence to treatment, preventive effect. We attempted to clarify these points in a randomized open, controlled, two parallel group study in a real-life setting.

METHODS

Five hundred and eleven patients with allergic rhinitis with or without intermittent asthma were randomized to drugs only or drugs + SLIT (rate 2 : 3) for 3 years. The clinical score (symptoms + drug intake) was measured each year during the allergen exposure. Pulmonary function test, methacholine challenge and skin tests were performed at the beginning and at the end of the study. Adherence to treatment was assessed by measuring the consumed extract.

RESULTS

Three hundred and nineteen patients received SLIT and 192 drugs only. Dropouts were 15% in the SLIT group and 12% in the controls. There was a significant improvement of clinical scores in the SLIT group: baseline 147 +/- 3.3, first year 72.9 +/- 1.3, second year 68.3 +/- 1.8, third year 54.7 +/- 2.8 (P < 0.0001 vs baseline).

CONTROL GROUP

baseline 138 +/- 2.3, first year 124.1 +/- 3.7, second year 111 +/- 3.3, third year 121 +/- 3.8 (P = NS). Only four patients reported systemic itching. Adherence was >80% in 72% and >60% in 18% of patients. The number of patients with a positive MCh challenge decreased significantly after 3 years only in the SLIT group. New skin sensitizations appeared in 38% of the controls and in 5.9% of the SLIT patients (P = 0.01).

CONCLUSION

Sublingual immunotherapy approximately halved the clinical scores and significantly reduced the bronchial hyperreactivity. Similarly to subcutaneous immunotherapy, SLIT displayed a preventive effect on the onset of new skin sensitizations. The adherence rate was quantitatively satisfactory.

Efficacy and safety of sublingual immunotherapy

OBJECTIVE

To review the available published data concerning the use of sublingual immunotherapy (SLIT) in respiratory allergy to primarily evaluate the clinical efficacy and safety of the treatment and to secondarily consider the mechanisms of action and any unresolved questions.

DATA SOURCES

Articles in the medical literature (starting from 1986 up to November 2003) derived from searching the MEDLINE database with the keywords sublingual immunotherapy, respiratory allergy, asthma, and rhinitis. Sources included review articles, randomized controlled clinical trials, postmarketing surveillance studies, and relevant reports from meeting proceedings.

STUDY SELECTION

Articles concerning safety, efficacy, and mechanisms of SLIT published in English-language, peer-reviewed journals.

RESULTS

SLIT proved effective and safe in adults and children. As with traditional subcutaneous immunotherapy, SLIT has long-lasting efficacy and a preventive effect on new sensitizations.

CONCLUSION

SLIT is a viable alternative to subcutaneous immunotherapy. Its use in pediatric patients seems to be particularly promising.

Safety of sublingual immunotherapy in children with asthma

INTRODUCTION

Two previously published studies on sublingual immunotherapy (SLIT) did not report any serious adverse event associated with the local therapy; however, adverse events were observed in greatly variable percentages. The aim of the study was to evaluate the tolerability profile of sublingual swallow and spit immunotherapy in a large number of children treated for allergic asthma.

METHODS

Adverse effects related to sublingual administration of allergen vaccines were evaluated in 354 children with allergic asthma. Each patient was followed for at least 37 months and received a monthly dose of major allergens (extract) in the range of 1.5-14.8mug, equivalent to 3-20 times the amount contained in the usual monthly maintenance injections via the subcutaneous routes.

RESULTS

No adverse event was observed in 90.4% of the children. We observed 0.155 mild to moderate reactions per 1000 administrations. Dosage adjustment was required in 15 patients. In five children, immunotherapy was stopped as a precaution - one patient developed rhino-conjunctivitis, two patients developed urticaria, and two children developed wheezing. None of the reactions were due to dosage errors. No anaphylactic reaction or multiple-organ life-threatening events occurred.

CONCLUSIONS

The results of our study showed an incidence of mild to moderate unwanted effects of 9.6%, lower than that previously reported, and no life-threatening adverse effects. Nevertheless, asthma, urticaria, and rhinoconjunctivitis can occur. SLIT is quite a safe therapy for the treatment of allergic children with asthma; however, careful evaluation of the single patient is necessary since SLIT is self-administered and a cumulative monthly dose higher than that normally administered as an injection is usually attainable.

The efficacy of sublingual immunotherapy for respiratory allergy is not affected by different dosage regimens in the induction phase

BACKGROUND

Sublingual administration of allergens is a safe and effective alternative to subcutaneous immunotherapy in patients with respiratory allergies. A drawback to this therapeutic approach is the relatively long and complex management of the induction phase.

AIM OF THE STUDY

To determine whether different induction regimens affect the outcome of sublingual immunotherapy.

METHODS AND RESULTS

Adult and pediatric patients with allergic rhinoconjunctivitis and/or asthma were included in the study. Ten subjects served as controls and received symptomatic treatments. Forty-three subjects were allocated to sublingual immunotherapy, with three different induction protocols (8-, 15- and 20-day, respectively). Symptom and medication scores, skin test results and (in asthmatic patients) FEV1 values were monitored for two years. Adverse effects were recorded. All induction regimens produced a significant improvement in symptom and medication usage (p < 0.0001); skin test scores decreased (p < 0.0001) and FEV1 improved (p < 0.05). In contrast, symptom and skin test scores did not significantly change in controls. No relevant adverse effects were observed with any of the induction regimens.

CONCLUSIONS

For patients with respiratory allergies, sublingual immunotherapy with an 8-day induction protocol is safe and effective. Our results encourage the usage of shorter induction regimens, which produce better compliance with this therapy.

Clinical practice guidelines and specific antigen immunotherapy

Allergy immunotherapy is a safe, effective treatment modality in selected patients. The length of therapy and the wide variety of patient sensitivities make it difficult to develop and test evidence-based guidelines in all areas of immunotherapy. A review of techniques and the evidence supporting them is provided in this article.

[Sublingual immunotherapy in children. Immunotherapy Committee of the Spanish Society for Clinical Immunology and Pediatric Allergology]

Sublingual immunotherapy is currently attracting growing interest because of its ease of administration and, according to previous studies, its infrequent and mild adverse effects. However, at least in children, the efficacy of this therapy has not been completely demonstrated. In addition, the mechanisms of action remain to be elucidated since few studies have been published and the results have been contradictory and sometimes inconclusive. For this reason, we performed a literature review through the MEDLINE database, selecting double-blind studies carried out in children. Only 10 studies meeting these requirements were retrieved. All the studies were performed by European researchers and nine were published in European journals. Efficacy was evaluated by clinical parameters and by reduction in medication use. The results on efficacy are not homogeneous, although most support the utility of this route of administration. Moreover, reports of allergens other than those used in these studies dust mites and grass pollens are lacking. In conclusion, further studies evaluating the efficacy of this therapy in children are required. Among the general population, if the efficacy of sublingual immunotherapy in the treatment of sensitization to hymenoptera venoms were demonstrated, as has been the case with subcutaneous immunotherapy, the utility of this route of administration would be definitively confirmed. Finally, sublingual immunotherapy could be used in children who have shown systemic reactions to subcutaneous immunotherapy or who refuse to undergo injections.

Immunotherapy for rhinitis

Allergen-specific immunotherapy in the treatment of allergic rhinitis has a well-documented clinical efficacy that indicates a statistically significant and clinically relevant reduction in symptom scores and the need for pharmacotherapy. The clinical efficacy of recently published studies is equivalent to or superior to the effect of standard anti-allergic drugs. Additional advantages are related to a downregulation of the allergic phenotype with the additional induction of a Th1 cytokine profile. The immunoregulatory capacity and the global downregulation of the allergic inflammation in mucous membranes might be important factors in the capacity to ensure long-term clinical efficacy (after termination of treatment) and the preventive capacity of immunotherapy in reducing the progression of rhinitis to asthma as well as deflowering the development of new sensitizations. Subcutaneous immunotherapy is optimal in severe allergic rhinitis with signs of bronchial hyperreactivity; however, sublingual immunotherapy might be an option for patients with milder disease.

Oral and sublingual immunotherapy in paediatric patients

PURPOSE OF REVIEW

Sublingual immunotherapy is becoming a routine treatment for respiratory allergy in several countries and it has been validated in international documents. This article will review the available literature on oral and sublingual immunotherapy, discussing the possible use of sublingual immunotherapy in paediatric patients.

RECENT FINDINGS

As oral immunotherapy was found to be poorly effective in clinical trials, its use has been discontinued. In contrast, several controlled studies have shown the efficacy of sublingual immunotherapy in children with allergic asthma and rhinitis, and a postmarketing survey has confirmed its safety. Moreover, new data on the long-lasting efficacy of this treatment and on the absence of local immunological effects have recently been published.

SUMMARY

The clinical efficacy and the optimal safety profile of sublingual immunotherapy make it a good candidate for treating respiratory allergy in children. Some aspects, such as the dose-response relationship and preventive effect, will be a research challenge for future developments and better definition of indications in children.

Advances in upper airway diseases and allergen immunotherapy

Epidemiologic studies continue to find an increased prevalence of rhinitis, asthma, and atopy in more westernized countries. Both allergic and nonallergic rhinitis are risk factors for development of asthma, particularly in adulthood. In patients who have both asthma and rhinitis, treatment of the latter decreases the likelihood of emergency department visits or hospitalization for asthma. The protective effect of intranasal cortico-steroids is much greater than that of antihistamines. This mirrors the effect on rhinitis symptoms, in which nasal corticosteroids are much more effective than antihistamines, leukotriene receptor antagonists, or the combination of both. In patients with severe asthma, sinus mucosal thickening on computed tomography (CT) correlates with the severity of lower airway disease indicated by sputum eosinophilia, exhaled nitrous oxide (NO), functional residual capacity, and diffusing capacity. Preseasonal specific immunotherapy (SIT) is less effective, but additive to treatment with omalizumab. It is also somewhat less effective in reducing nasal symptoms than nasal corticosteroids; however, it is superior to them for reducing lower airway inflammation. SIT in children with only allergic rhinitis reduces both the incidence of asthma and bronchial hyperresponsiveness to methacholine. High-dose sublingual immunotherapy appears to be safe and effective, but less effective than injection immunotherapy. It is not clear that there are cost savings with sublingual immunotherapy, as home administration savings may be offset by the much larger amount of allergen extracts required. New approaches to allergen immunotherapy, designed to increase efficacy and safety, include conjugation of allergens to immunostimulatory sequences and encapsulation in liposomes. Cross-reactivity between inhalants and foods demonstrated by skin prick tests is more predictive of clinically important sensitivity than is that demonstrated by RAST testing. The latter, because of cross-reacting profilins, is often clinically irrelevant.

Noninjection routes for immunotherapy

Allergen specific immunotherapy, together with drugs and allergen avoidance, is a cornerstone in the management of respiratory allergy. The traditional subcutaneous route is burdened with the risk of severe adverse events; therefore, safer routes of administration (noninjection or local routes) have been investigated and developed. Controlled trials failed to demonstrate the clinical efficacy and the safety of oral and bronchial administration, and these routes have been abandoned. Local nasal immunotherapy proved effective and safe in 17 of 18 controlled trials; thus it is considered a viable route of immunotherapy. Nevertheless, nasal immunotherapy is effective in rhinitis only and requires a particular administration technique; therefore its use is slowly declining. The sublingual route is supported by numerous controlled trials showing its efficacy in asthma and rhinitis in adults and children. The safety profile, assessed in clinical trials and postmarketing surveillance studies, is satisfactory; the most frequent side effects are gastrointestinal complaints, which can be easily managed by proper dose adjusting. Sublingual immunotherapy is now accepted by the World Health Organization as a valid alternative to the subcutaneous route also in children. Although the long-lasting efficacy has been recently documented for the sublingual route, several points still need to be elucidated, including mechanisms of action, optimal dosage, cost-effectiveness, and adherence.

Long-lasting effect of sublingual immunotherapy in children with asthma due to house dust mite: a 10-year prospective study

BACKGROUND

Subcutaneous immunotherapy for respiratory allergy has shown a long-lasting efficacy after its discontinuation, whereas this evidence is still lacking for sublingual immunotherapy, despite the fact that it is widely used.

OBJECTIVE

We aimed to evaluate whether a long-lasting effect of SLIT occurs, in a prospective parallel group controlled study.

METHODS

Sixty children (mean age 8.5 years) suffering from allergic asthma/rhinitis due to mites were subdivided into two matched groups: 35 underwent a 4- to 5-year course of SLIT with standardized extract and 25 received only drug therapy. The patients were evaluated at three time points (baseline, end of SLIT and 4 to 5 years after SLIT discontinuation) regarding presence of asthma, use of anti-asthma drugs, skin prick tests and specific IgE.

RESULTS

We found that in the SLIT group there was a significant difference vs. baseline for the presence of asthma (P </= 0.001) and the use of asthma medications (P </= 0.01), whereas no difference was observed in the control group. The mean peak expiratory flow result was significantly higher in the active group than in the control group after 10 years. No change was seen as far as new sensitizations were concerned. Specific IgE showed a near-significant increase (baseline vs. 10 years, P = 0.06) only in the control group.

CONCLUSION

Our study demonstrates that sublingual immunotherapy is effective in children and that it maintains the clinical efficacy for 4 to 5 years after discontinuation.

Sublingual immunotherapy for allergic rhinitis

BACKGROUND

Allergic rhinitis is a common condition which, at its most severe, can significantly impair quality of life despite optimal treatment with antihistamines and topical nasal corticosteroids. Allergen injection immunotherapy significantly reduces symptoms and medication requirements in allergic rhinitis but its use is limited by the possibility of severe systemic reactions. There has therefore been considerable interest in alternative routes for delivery of allergen immunotherapy, particularly the sublingual route.

OBJECTIVES

To evaluate the efficacy of sublingual immunotherapy (SLIT), compared with placebo, for reductions in symptoms and medication requirements.

SEARCH STRATEGY

The Cochrane Controlled Trials Register, MEDLINE (1966-2002), EMBASE (1974-2002) and Scisearch were searched, up to September 2002, using the terms (Rhin* OR hay fever) AND (immunotherap* OR desensiti*ation) AND (sublingual).

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

Data from identified studies were abstracted onto a standard extraction sheet and subsequently entered into RevMan 4.1. Analysis was performed by the method of Standardised Mean Differences (SMD) using a random effects model. P values <0.05 were considered statistically significant. Subgroup analyses were performed according to the type of allergen administered, the age of participants and the duration of treatment.

MAIN RESULTS

Twenty two trials involving 979 patients were included. There were 6 trials of SLIT for House Dust Mite allergy, 5 for Grass Pollen, 5 for Parietaria, 2 for Olive and one each for, Ragweed, Cat, Tree and Cupressus. Four studies enrolled exclusively children. Seventeen studies administered the allergen by sublingual drops subsequently swallowed, 3 by drops subsequently spat out and 2 by sublingual tablets. Eight studies involved treatment for less than 6 months, 10 studies for 6-12 months and 4 studies for greater than 12 months. All included studies were double-blind placebo-controlled trials of parallel group design. Concealment of treatment allocation was considered adequate in all studies and the use of identical placebo preparations was almost universal. There was significant heterogeneity, most likely due to widely differing scoring systems between studies, for most comparisons. Overall there was a significant reduction in both symptoms (SMD -0.34, 95% confidence interval -0.69 to -0.15; p=0.002) and medication requirements (SMD -0.43 [-0.63, -0.23]; p=0.00003) following immunotherapy. Subgroup analyses failed to identify a disproportionate benefit of treatment according to the allergen administered. There was no significant reduction in symptoms and medication scores in those studies involving only children but total numbers of participants were small, casting doubt on the validity of the conclusion. Increasing duration of treatment does not clearly increase efficacy. The total dose of allergen administered may be important but insufficient data were available to analyse this factor.

REVIEWER'S CONCLUSIONS

SLIT is a safe treatment which significantly reduces symptoms and medication requirements in allergic rhinitis. The size of this benefit compared to that of other available therapies, particularly injection immunotherapy, is not clear, having been assessed directly in very few studies. Further research is required concentrating on optimising allergen dosage and patient selection.

Is sublingual immunotherapy clinically effective?

PURPOSE OF REVIEW

Sublingual immunotherapy has become increasingly popular and in some countries more allergic patients are treated by the sublingual route than the subcutaneous route. Evaluation of the scientific documentation for clinical efficacy is important before a treatment is used without restriction. This review critically analyses every placebo-controlled, double-blind study providing symptom/medication scores for the primary outcome; that is, a significant and clinically relevant reduction in disease severity of actively treated patients.

RECENT FINDINGS

In total 23 papers fulfill the evaluation criteria; 26% are categorized as unequivocally effective, 35% are possibly effective (significant improvement in either symptom or medication scores), and 39% have no statistically documented efficacy.

SUMMARY

The majority of papers have used an inadequate study design that may be responsible for the large number of inconclusive and negative studies. Before sublingual immunotherapy can be recommended as a routine treatment, more documentation for beneficial efficacy is needed.