Clinical and immunological effects of immunotherapy with alum-absorbed grass allergoid in grass-pollen-induced hay fever

The safety of carbamylated monomeric allergoids for sublingual immunotherapy. Data from a pharmacovigilance study

Aim: Sublingual immunotherapy (SLIT) is significantly less concerned by systemic reactions than subcutaneous immunotherapy. Allergoids were introduced to reduce systemic reaction to subcutaneous immunotherapy, but may also be used for SLIT. Methods: This pharmacovigilance study evaluated the post-marketing reports collected in a safety database, including the number and the type (serious or not serious) of adverse drug reactions (ADRs) in Italy by SLIT with the carbamylated monomeric allergoid (CMA). Results: More than 15,000,000 CMA tablets were administered, with 25 spontaneous reports of ADRs, only two being serious. Conclusion: The rate of ADRs to CMA we found in this pharmacovigilance survey, corresponding to 0.0004% of all administered doses, is far lower than the rates commonly reported for allergen SLIT products.

Allergen immunotherapy for allergic rhinoconjunctivitis: A systematic review and meta-analysis

BACKGROUND

The European Academy of Allergy and Clinical Immunology (EAACI) is in the process of developing Guidelines on Allergen Immunotherapy (AIT) for Allergic Rhinoconjunctivitis. To inform the development of clinical recommendations, we undertook a systematic review to assess the effectiveness, cost-effectiveness, and safety of AIT in the management of allergic rhinoconjunctivitis.

METHODS

We searched nine international biomedical databases for published, in-progress, and unpublished evidence. Studies were independently screened by two reviewers against predefined eligibility criteria and critically appraised using established instruments. Our primary outcomes of interest were symptom, medication, and combined symptom and medication scores. Secondary outcomes of interest included cost-effectiveness and safety. Data were descriptively summarized and then quantitatively synthesized using random-effects meta-analyses.

RESULTS

We identified 5960 studies of which 160 studies satisfied our eligibility criteria. There was a substantial body of evidence demonstrating significant reductions in standardized mean differences (SMD) of symptom (SMD -0.53, 95% CI -0.63, -0.42), medication (SMD -0.37, 95% CI -0.49, -0.26), and combined symptom and medication (SMD -0.49, 95% CI -0.69, -0.30) scores while on treatment that were robust to prespecified sensitivity analyses. There was in comparison a more modest body of evidence on effectiveness post-discontinuation of AIT, suggesting a benefit in relation to symptom scores.

CONCLUSIONS

AIT is effective in improving symptom, medication, and combined symptom and medication scores in patients with allergic rhinoconjunctivitis while on treatment, and there is some evidence suggesting that these benefits are maintained in relation to symptom scores after discontinuation of therapy.

Dose-response relationship of a new Timothy grass pollen allergoid in comparison with a 6-grass pollen allergoid

BACKGROUND

Subcutaneous allergen immunotherapy with grass pollen allergoids has been proven to be effective and safe in the treatment of patients with allergic rhinoconjunctivitis. Based on the extensive cross-reactivity among Pooideae species, it has been suggested that grass pollen extracts could be prepared from a single species, rather than from a multiple species mixture.

OBJECTIVE

To find the optimal dose of a Phleum pratense (P. pratense) allergoid preparation and compare its efficacy and safety to a 6-grass pollen allergoid preparation.

METHODS

In this double-blind, placebo-controlled study (EudraCT: 2011-000674-58), three doses of P. pratense allergoid (1800 therapeutic units (TU), standard-dose 6000 TU and 18 000 TU) were compared with placebo and the marketed 6-grass pollen allergoid (6000 TU). In a pre-seasonal dosing regimen, 102 patients were randomized to five treatment groups and received nine subcutaneous injections. The primary efficacy endpoint was the change in weal size (late-phase reaction [LPR]) in response to the intracutaneous testing (ICT) before and after treatment, comparing the active allergoids to placebo. Secondary outcomes were the change in Total Nasal Symptom Score (TNSS) assessed in the allergen exposure chamber (AEC), the changes in P. pratense-serum-specific IgG₄ and the incidence of adverse events (AEs).

RESULTS

All three doses of the P. pratense and the 6-grass pollen allergoid preparations were significantly superior to placebo for the primary outcome, whereas there were no significant differences in the change in TNSS. Compared to the standard-dose, the high-dose of P. pratense did not produce any additional significant benefit, but showed a slight increase in AEs. Yet this increase in AEs was lower than for the 6-grass pollen preparation.

CONCLUSIONS & CLINICAL RELEVANCE

The standard-dose of the new P. pratense allergoid was comparable to the marketed 6-grass pollen preparation at equal dose for the parameters measured.

The efficacy assessment of a self-administered immunotherapy protocol

Background

We previously reported the safety of a self‐administered subcutaneous immunotherapy (SCIT) protocol. Here we report the results of the retrospective efficacy trial of the United Allergy Service (UAS) self‐administered SCIT protocol. We hypothesized that by utilizing a slow SCIT buildup phase, designed to attain recommended allergen concentrations on a cumulative basis, efficacious outcomes and clinical relevance would be achieved.

Methods

We enrolled 60 SCIT patients and 56 control patients. The study contrasted baseline and treatment period combined symptom plus medication scores (CSMS) as the primary outcome measure and rhinoconjunctivitis quality of life questionnaire (RQLQ) scores as the secondary study outcome measure. Changes in pollen counts were also examined with regard to effects on these efficacy parameters.

Results

The treatment group showed significantly improved CSMS (standardized mean difference [SMD]: −1.57; 95% confidence interval [CI], −1.97 to −1.18; p < 0.001) and RQLQ (SMD: −0.91; 95% CI, −1.23 to −0.59; p < 0.001). These treatment group outcome measures were respectively improved by 33% and 29% compared to baseline and greater than 40% in comparison to the control group (p < 0.0001). Significant results were also shown when examining these outcome measures with regards to either monotherapy or poly‐allergen SCIT. Furthermore, a comparison to recent meta‐analyses of SCIT studies showed equivalent efficacy and clinical relevance. Assessment of pollen counts during the baseline and treatment periods further corroborated the efficacy of the UAS SCIT protocol.

Conclusion

These efficacy results, and our previous safety results, show that a carefully designed and implemented self‐administered SCIT protocol is efficacious and safe.

Efficacy of subcutaneous and sublingual immunotherapy with grass allergens for seasonal allergic rhinitis: a meta-analysis-based comparison

BACKGROUND

Subcutaneous (SCIT) and sublingual (SLIT) immunotherapy are the 2 most prescribed routes for administering allergen-specific immunotherapy. They were shown to be effective in control of symptoms and in reducing rescue medication use in patients with allergic diseases, but their effectiveness has to be balanced against side effects. In recent years, SLIT has been increasingly prescribed, instead of SCIT, because of improved safety and easy administration.

OBJECTIVE

We assessed which route is the most effective in the treatment of patients with seasonal allergic rhinitis to grass pollen.

METHODS

An indirect meta-analysis-based comparison between SCIT and SLIT was performed. Treatment efficacy was determined as the standardized mean difference (SMD) in symptom and medication scores obtained with active treatment, SCIT or SLIT, compared with placebo. Studies were included if they were double-blind randomized controlled trials comparing SCIT or SLIT with placebo. Thirty-six randomized controlled trials (3014 patients; 2768 controls) were analyzed.

RESULTS

The overall effect size of SCIT for symptom score (SMD, -0.92; 95%CI, -1.26 to -0.58) was significantly higher than SLIT, both administered via drops (SMD, -0.25; 95% CI, -0.45 to -0.05) and tablets (SMD, -0.40; 95%CI, -0.54 to -0.27). Similar results were reported for medication score (SCIT: SMD, -0.58; 95% CI, -0.86 to -0.30. SLIT drops: SMD, -0.37; 95% CI, -0.74 to -0.00. SLIT tablets SMD, -0.30; 95% CI, -0.44 to -0.16).

CONCLUSIONS

Our results provide indirect but solid evidence that SCIT is more effective than SLIT in controlling symptoms and in reducing the use of antiallergic medications in seasonal allergic rhinoconjuntivitis to grass pollen.

Desensitization effect of preseasonal seven-injection allergoid immunotherapy with olive pollen on basophil activation: the efficacy of olive pollen-specific preseasonal allergoid immunotherapy on basophils

BACKGROUND

It has previously been demonstrated that subcutaneous immunotherapy with allergoids positively affects clinical and immunological parameters even after 7 preseasonal injections. However, its effect on basophil activation remains unclear. We investigated the effect of preseasonal allergoid immunotherapy on basophils and concomitantly assessed its clinical and immunological efficacy in olive pollen-monosensitized patients.

METHODS

This study enrolled 437 consecutive patients with respiratory allergy and positive skin prick tests (SPTs); 212 (48.5%) patients were sensitized to olive pollen, and 33 (7.5%) patients were sensitized to olive pollen only. Of these patients, 23 received preseasonal immunotherapy with an olive pollen allergoid. The olive pollen-specific basophil activation, the titrated nasal provocation test, the nasal symptom score, and olive pollen-specific IgE, IgG1 and IgG4 levels were evaluated before immunotherapy and 8 months after the end of immunotherapy in the follow-up visit.

RESULTS

In comparison to baseline evaluation, 7 preseasonal injections of an allergoid resulted in a significant decrease in the percentage of basophils expressing CD63 (29 vs. 7%, respectively, p < 0.0001) and a significant increase in the titrated nasal provocative dose (1/10 vs. 1/1, respectively, p < 0.01). SPT induration diameters caused by an olive pollen extract decreased (12 mm at baseline vs. 5.5 mm at follow-up, p < 0.005), as did nasal symptom score (7 at baseline vs. 3 at follow-up, p < 0.01). Olive pollen-specific IgE (17.5 vs. 50 kU/l, p < 0.012), IgG1 (0.16 vs. 2.9 µg/ml, p < 0.0001) and IgG4 (0.07 vs. 1.92 µg/ml, p < 0.0001) levels significantly increased.

CONCLUSIONS

Immunotherapy with 7 preseasonal injections of an olive pollen allergoid decreases olive pollen-specific basophil activation over 8 months, an effect observed in vitro and in vivo.

Towards evidence-based medicine in specific grass pollen immunotherapy

When initiating grass pollen immunotherapy for seasonal allergic rhinoconjunctivitis, specialist physicians in many European countries must choose between modalities of differing pharmaceutical and regulatory status. We applied an evidence-based medicine (EBM) approach to commercially available subcutaneous and sublingual Gramineae grass pollen immunotherapies (SCIT and SLIT) by evaluating study design, populations, pollen seasons, treatment doses and durations, efficacy, quality of life, safety and compliance. After searching MEDLINE, Embase and the Cochrane Library up until January 2009, we identified 33 randomized, double-blind, placebo-controlled trials (including seven paediatric trials) with a total of 440 specific immunotherapy (SIT)-treated subjects in seven trials (0 paediatric) for SCIT with natural pollen extracts, 168 in three trials (0 paediatric) for SCIT with allergoids, 906 in 16 trials (five paediatric) for natural extract SLIT drops, 41 in two trials (one paediatric) for allergoid SLIT tablets and 1605 in five trials (two paediatric) for natural extract SLIT tablets. Trial design and quality varied significantly within and between SIT modalities. The multinational, rigorous trials of natural extract SLIT tablets correspond to a high level of evidence in adult and paediatric populations. The limited amount of published data on allergoids prevented us from judging the level of evidence for this modality.

Cluster immunotherapy with a glutaraldehyde-modified mixture of grasses results in an improvement in specific nasal provocation tests in less than 2.5 months of treatment

BACKGROUND

Cluster immunotherapy is becoming increasingly used. It allows for a rapid build up phase and the administration of higher doses of allergen in a shorter period of time.

OBJECTIVES

To evaluate the effect of short-term pre-seasonal immunotherapy using a glutaraldeyde-modified allergen vaccine in reducing specific nasal hyperreactivity in nasal challenge tests.

MATERIALS AND METHODS

Thirty-three patients were selected. All patients had a positive history of allergic rhinitis and skin tests to grass pollen, although most of them (72.7%) were sensitized to other allergens as well. The study was conducted outside of the pollen season and the patients did not receive any pharmacological treatment during this period of time. Two randomized groups of patients were established; Group A: 22 patients (13 females and nine males) and Group B, 11 control patients (seven females and four males). Patients in Group A received immunotherapy with a vaccine containing 50% of the wild grasses Trisetum paniceum and Dactylis glomerata. All patients underwent titrated nasal provocation tests (NPT) before and after completion of the study (2.3 and 2.8 months for Groups A and B, respectively). The administration schedule consisted of 0.1 and 0.2 mL at day 1, followed by 0.3 and 0.5 mL at day 7, 0.5 mL after 2 weeks followed by 0.5 mL monthly. A single vial was used containing an allergen concentration of 10 000 TU/mL (105 microg of total protein and 24.6 microg of Group 1 plus 5 allergens/mL). A mean of 6.5 injections were administered to Group A patients between NPTs.

RESULTS

There were no significant differences between both groups at the beginning of the study (P=0.48). At the end, only Group A patients needed significant greater threshold concentrations for a positive NPT than at the beginning (P=0.002).

CONCLUSIONS

A short-term cluster pre-seasonal inmunotherapy with a modified vaccine containing a mixture of grass pollen is effective as determined by an objective measure after only a mean 2.3 months of treatment.

Tolerance and immunological changes of chemically modified allergen vaccine of Parietaria judaica in accelerated schedules

The physicochemical modification of allergen vaccines provides a chance for administering higher doses in a shorter period of time. We sought to assess the safety and immunological changes of using a biologically standardized and modified Parietaria judaica pollen extract in accelerated schedules. Two accelerated schedules were tested in 45 P. judaica-allergic patients: 20 patients reached the maximum dose after two visits using two different concentrations and 25 patients reached the maximum dose after only one visit with two injections of the maximum concentration vial. The tolerance was assessed by recording all side effects related with immunotherapy. Specific antibody levels against native extract and rPar j 2 allergen were evaluated at the beginning and the end of the study. Allergenic potency determined by enzyme allergosorbent test (EAST) inhibition and skin prick test showed that modified P. judaica pollen had a 99.9% less allergenicity than native extract. After 650 doses administered, two clinically irrelevant local reactions (diameter<0 x 5 cm) and no systemic reactions were registered. Significant increases in allergen-specific IgG4 and IgG against P. judaica extract and rPar j 2 and significant decrease of specific IgE against Par j 2 were observed. The modified extract of P. judaica is safe to treat sensitive patients, even at accelerated regimens, and induces significant immunological changes.

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.

The effects of grass pollen allergoid immunotherapy on clinical and immunological parameters in children with allergic rhinitis

Allergoid immunotherapy is a new form of allergen immunotherapy allowing safe administration of high allergen doses. There is limited information on the effects of allergoid immunotherapy in children with allergic rhinitis. To investigate the immunological and clinical effects of allergoid immunotherapy in children with allergic rhinitis due to grass pollen allergy. Children with allergic rhinitis were assigned to allergoid immunotherapy (n = 27) or control (n = 26, no immunotherapy) groups. Children in the immunotherapy group received seven injections of grass pollen allergoid immunotherapy before grass pollen season and continued to receive maintenance immunotherapy for 27 months. All patients were offered a pharmacotherapy regimen to be used on demand during the pollen seasons. Clinical and laboratory parameters were compared between the immunotherapy and control groups. The rhinoconjunctivitis symptom-medication score and asthma symptom score were lower in the immunotherapy group after 1 yr of maintenance immunotherapy (p < 0.01 for both). Skin test reactivity and nasal reactivity as determined by nasal provocation testing for grass pollen were significantly decreased after 1 yr of immunotherapy (p < 0.001 for both). The seasonal increase in bronchial reactivity and nasal lavage eosinophil cationic protein levels were prevented after the first year of immunotherapy (p < 0.05 for both). The seasonal increase in immunoglobulin (Ig)E decreased (p < 0.05) and grass-specific IgG, IgG(1) and IgG(4) increased significantly already at the end of the seven-injection build-up therapy (p < 0.001, for all). Interleukin (IL)-4 levels in the culture supernatants showed a steady decline from baseline at first and second year of immunotherapy (p < 0.001) but remained unchanged in the control group. Allergoid immunotherapy is an effective method in the treatment of grass pollen-induced allergic rhinitis in children and prevents the seasonal increase in bronchial hyper-reactivity. Changes in specific IgE and IgG levels and decreased IL-4 production in peripheral blood mononuclear cell culture supernatants may account for the observed clinical effects.

Efficacy and safety of preseasonal-specific immunotherapy with an aluminium-adsorbed six-grass pollen allergoid

BACKGROUND

The clinical efficacy and safety of a six-grass pollen allergoid has been studied. The advent of more exacting clinical guidelines and a better appreciation of the possible mechanisms of treatment prompted this reappraisal.

METHODS

A 2-year double-blind multicentre placebo-controlled phase 3 clinical trial was undertaken in 154 patients suffering symptoms of rhinoconjunctivitis with or without asthma (GINA I or II). Therapy comprised two consecutive preseasonal short-courses of subcutaneous injections using a grass pollen allergoid adsorbed to aluminium hydroxide.

RESULTS

A combined symptom and medication score (SMS) was used as the primary end-point for clinical efficacy. SMS from the first year showed a significant difference of 26.6% between the two study groups (P=0.026) and this was improved after the second year when there was a 48.4% difference in SMS between active and placebo treatment in favour of the allergoid (P = 0.018). Highly significant increases in grass pollen allergen-specific IgG1 and IgG4 antibody concentrations were measured in association with active treatment. Allergen tolerance was increased as judged by a conjunctival provocation test and significant improvements in quality of life were documented using a standardized questionnaire. The allergoid was well tolerated.

CONCLUSIONS

The grass pollen allergoid was shown to be safe and clinically efficacious in the management of hay fever with or without asthma (GINA I or II).

Is immunotherapy-induced birch-pollen-specific IgG4 a marker for decreased allergen-specific sensitivity?

BACKGROUND

The role of IgG4 during allergen-specific immunotherapy (SIT) is still controversial. The available studies present paramount differences in in vitro techniques, allergens, and clinical outcome parameters. By implementing a sensitive method, and pivotal clinical outcome parameters, we wanted to ascertain the utility of IgG4 as a clinical marker of decreased allergen-specific sensitivity to a common aeroallergen.

METHODS

Sera were drawn from 23 birch-pollen-allergic patients during a placebo-controlled clinical trial on birch pollen SIT. Seventeen patients received active treatment. Blood samples were drawn at 0, 2, 4, 7, and 30 treatment weeks, and 36 months. The binding activity of autologous IgG, IgG4, IgE, and IgE- and/or IgG-depleted serum to (125)I-labelled recombinant Bet v 1 was assessed in a fluid-phase radioimmunoassay. Disease severity was assessed subjectively on a visual analogue scale (VAS), and objectively by intradermal late-phase reaction diameters.

RESULTS

Before SIT IgG4 fraction of IgG-allergen binding varied from 4 to 74%, with a median of 36%, increasing to 71% after 36 months. Changes in IgG4 or IgG4/IgG fraction were not correlated to clinical outcome parameters. Changes in IgG allergen binding and VAS were significantly correlated (sigma = 0.72; p < 0.05). SIT increased the serum-blocking activity of IgE allergen binding from 25% before SIT to 80% after SIT. No changes were observed in the placebo group.

CONCLUSION

The data suggest that IgG4 per se is a poor marker of decreased allergen-specific sensitivity to birch pollen, both as a single measurement and as delta values.

The blocking activity of birch pollen-specific immunotherapy-induced IgG4 is not qualitatively superior to that of other IgG subclasses

Allergen-specific IgG antibodies induced by specific immunotherapy (SIT) interfere with the allergen-IgE interaction, and act as blocking antibodies in vitro. It has been hypothesised that IgG4, as opposed to other IgG subclasses, is particularly important in this function, which may play a role for the clinical efficacy of SIT. In this study, fractionated serum samples from 14 SIT-treated birch pollen allergic individuals enabled determination of the inhibitory capacity of IgG4 alone versus non-IgG4 IgG. Allergen-binding activities of IgG and the IgG-mediated inhibition of allergen binding to autologous IgE were detected using 125I-labelled rBet v 1.2801, a recombinant variant of the major allergen of Betula verrucosa pollen. Results show that IgG4-depletion resulted in equivalent reductions in binding and blocking activities. In contrast, a significant but less than two-fold higher relative blocking activity was found in the purified IgG4 fraction. There was no significant difference in the binding avidities (1/K(d)) measured in the two IgG fractions. Thus, it appears that SIT-induced specific IgG4 contributes to the IgG blocking of allergen binding to IgE in a simple quantitative manner and not by a particular intrinsic blocking activity.

Safety of rush immunotherapy to multiple aeroallergens in an adult population

BACKGROUND

Rush immunotherapy has many potential benefits but a higher incidence of systemic reactions compared with traditional immunotherapy. The safety of rush immunotherapy to multiple aeroallergens has not been widely studied.

OBJECTIVE

To examine the safety of rush immunotherapy to multiple aeroallergens in a primarily adult population and to identify risk factors for systemic reactions.

METHODS

A retrospective review of 65 patients who received rush immunotherapy to multiple aeroallergens in a university-based allergy practice was conducted. All patients were premedicated with prednisone, cetirizine, ranitidine, and zafirlukast or montelukast. Percutaneous skin testing was performed, major allergen content was analyzed in every fourth patient's immunotherapy extract, and systemic reactions were graded.

RESULTS

Systemic reactions were observed in 25 patients (38%). All systemic reactions occurred with the final 3 doses of the protocol. Most (72%) occurred after the final dose of the protocol. Nineteen (76%) of the reactions were mild, 5 (20%) were moderate, and 1 (4%) was severe. Systemic reactions were associated with a higher degree of skin test sensitivity and the presence of weed or dog allergen in the extract (vaccine).

CONCLUSIONS

Rush immunotherapy is associated with a relatively high incidence of systemic reactions, but most reactions are mild and easily treated. The degree of skin sensitivity to the allergens administered and the presence of dog or weed allergen in the extract may be predictors for the development of systemic reactions.

Biological characterization of glutaraldehyde-modified Parietaria judaica pollen extracts

BACKGROUND

Allergoids are widely used in specific immunotherapy (SIT) for the treatment of IgE-mediated allergic diseases, but all techniques for standardization of conventional allergic extracts may not be appropriate for standardization of a glutaraldehyde (GA)-modified extract because of the unique characteristics of these extracts.

OBJECTIVE

To assess an accurate methodology for standardization of chemically modified extracts.

METHODS

GA-modified extracts from Parietaria judaica pollen were purified by diafiltration. Biochemical properties were investigated by determination of amino groups, chromatography, and SDS-PAGE. The IgE-binding activity was determined by skin prick test, enzyme allergosorbent test inhibition, basophil activation, and histamine release tests. Peripheral blood mononuclear cells (PBMCs) from P. judaica pollen-allergic subjects were stimulated with either native or allergoid extracts, and proliferation was measured.

RESULTS

Biochemical data indicated a high degree of allergen polymerization resulting in extract components higher than 100 kDa. IgE-binding activity, both in vivo and in vitro, was reduced by more than 99.8%. Both allergen and allergoid induced PBMC proliferation and synthesis of blocking IgG antibodies at similar rates. Moreover, no evidence of introduction of new determinants by chemical modification was found.

CONCLUSIONS

The preparation of GA-modified extracts by diafiltration is faster and more reliable than previous chromatographic methods. These modified extracts have drastically reduced their allergenicity while maintaining their immunogenicity, and therefore they can be used in safer and shortened schedules of SIT.

Analysis of the CD4+ T cell responses to house dust mite allergoid

BACKGROUND

Modified allergen extracts (allergoids) with reduced IgE-binding capacity are successfully used in immunotherapy of atopic allergy. Their reduced T-cell stimulatory capacity is less well studied and is a subject of the present study.

METHODS

We compared the ability of native house dust mite extract (Dermatophagoides pteronyssinus; HDM) and the glutaraldehyde-modified allergoid (HDM-GA) to induce the proliferation and cytokine production by fresh PBMC and by DC-stimulated polyclonal Th cells and HDM-specific Th cell clones.

RESULTS

Freshly isolated T cells showed a partially reduced responsiveness to HDM-GA, differentially pronounced in different donors. HDM-specific Th cell clones prepared from three donors showed either a complete loss of reactivity to HDM-GA, or completely preserved responsiveness. The frequency of nonreactive clones was donor-dependent (2/3, 3/10 and 1/10). GA modification of HDM did not interfere with the cytokine production profile of HDM-specific T cell clones.

CONCLUSIONS

The reduced stimulatory potential of HDM-GA results mainly from a loss of certain Th cell epitopes, rather than impaired allergen uptake and presentation, or induction of suppressive factors. Varying frequencies of allergoid-nonreactive HDM-specific Th cells may result in differential responses of individual patients to immunotherapy.

Development of new IgE specificities to allergenic components in birch pollen extract during specific immunotherapy studied with immunoblotting and Pharmacia CAP System

BACKGROUND

New IgE sensitizations to proteins in allergen extracts have been shown to occur during allergen-specific immunotherapy (IT). However little is known about the kinetics of the changes in antibody reactivities.

METHODS

Twenty-four allergic children and adults were treated with birch pollen rush IT (RIT). Fifteen matched patients served as allergic controls. Sera were obtained at regular intervals for up to three years and analyzed with immunoblotting and Pharmacia CAP System with recombinant (r) birch pollen allergens (rBet v 1, rBet v 2, and rBet v 4).

RESULTS

All birch-allergic patients had specific IgE to the major birch pollen allergen Bet v 1, but only three had IgE to rBet v 2 and/or rBet v 4 at the beginning of the study. New IgE sensitizations developed in 65% of the birch RIT-treated patients when studied by immunoblotting. Twenty-nine percent of the patients developed new sensitizations to rBet v 2 and/or rBet v 4 during RIT as measured by Pharmacia CAP System. Generally, new specific IgE reactivities occurred after at least one year of RIT, and only at low levels (< 1 kUA/l).

CONCLUSIONS

Sensitization to additional allergenic pollen components frequently occurs during prolonged birch RIT. However, the IgE levels are low and the clinical relevance is not known.

Long-term efficacy of preseasonal grass pollen immunotherapy in children

BACKGROUND

In a previous controlled study we demonstrated that preseasonal grass pollen immunotherapy for three years was effective in children. In the current study we examined the same group of patients to see if there is still a benefit six years after discontinuation of treatment.

METHODS

Thirteen of 14 patients with previous specific immunotherapy (SIT) and 10 out of 14 patients of the control group were prospectively followed during the grass pollen season. Outcome measures were seasonal symptom scores for eyes, nose and chest, the use of symptomatic medication and visual analog scale. Objective measures included skin prick test reactivity to seasonal and perennial allergens and conjunctival provocation testing.

RESULTS

During the 13 week observation time scores for overall hayfever symptoms (P < 0.004) and individual symptoms for eyes (P < 0.02), nose (P < 0.04) and chest (P < 0.01) as well as combined symptom and medication scores (P < 0.002) remained lower in the group with previous SIT. Only 23% of patients with previous pollen-asthma who had received SIT experienced pollen-associated lower respiratory tract symptoms compared to 70% in the control group (P < 0.05). There was no significant difference in the use of pharmacological treatment during the pollen season except for asthma medication. The average visual analog scale was lower in the post-SIT group (P < 0.05). Six years after cessation of SIT the immediate skin response to grass pollen remained decreased compared to the reaction of the controls (P < 0.01). There was also a tendency for higher allergen concentration to provoke a conjunctival response in the post-SIT group but without reaching statistical significance. Eight years after commencement of SIT, 61% of the initially pollen-monosensitized children had developed new sensitization to perennial allergens compared to 100% in the control group (P < 0.05).

CONCLUSIONS

There is still a significant clinical benefit six years after discontinuation of preseasonal grass pollen immunotherapy in childhood. SIT in children with pollen-allergy reduces onset of new sensitization and therefore has the potential to modify the natural course of allergic disease.

Does allergen immunotherapy alter the natural course of allergic disorders?

Allergy in patients with atopy is caused by clinical adverse reactions to environmental antigen, which is often associated with allergen-specific immunoglobulin (Ig)E production. Since allergy reflects an inappropriate immunological reaction, a therapeutic approach related to immunology is likely to actively alter the natural course of allergic disorders. Allergen immunotherapy, known at various times as desensitisation or hyposensitisation, is very recently defined by the World Health Organization as therapeutic vaccines for allergic diseases. At present, it has become a common clinical practice in selected patients for the treatment and prevention of the recurrence of allergic disorders caused by insect venoms and has proven to be effective in changing the course of allergic responses induced by grass and tree pollen, animal hair and dander, house dust mite and mold, as demonstrated by improvement in clinical symptoms, skin prick test and medication scores. Reported effects of allergen immunotherapy on the natural course of allergic disorders include (i) prevention of reaction following re-sting in insect venom allergy; (ii) prevention or decrease the rate of the natural progress of allergic rhinitis to asthma; and (iii) inhibition of new sensitisation in monosensitised children. Many aspects of the immune responses associated with allergic disorders, including antibody production, cytokine secretion, T cell activation and local inflammatory reactions, are found to be significantly altered during and/or after immunotherapy. Specifically, the ratio of allergen-specific IgG4 to IgG1 correlates well with positive clinical outcome caused by allergen immunotherapy in patients with pollen-allergy. Allergen immunotherapy affects the cytokine profile of allergen-specific T cells and switches T(H)2 type immune responses in patients with atopy towards T(H)0 or T(H)1 type responses. Although the changes in the absolute value of T(H)1 or T(H)2 cytokines appear quite variable, the increase in the ratio of T(H)1/T(H)2 cytokines is very consistent among published reports, especially in the late stage of treatment. Accumulating evidence indicates that appropriate immunotherapy prevents the onset of new sensitisation and prevents the progress of allergic rhinitis to asthma. Although the changes in B cell and T cell responses, especially IgG antibodies and T(H)1/T(H)2 cytokine production, may be the major mechanism underlying the clinical efficacy of allergen immunotherapy and the prevention of the development of allergic phenotypic changes, multiple mechanisms may be involved in the outcome of alteration of the natural course of allergic disorders.

Immunotherapy with a calcium phosphate-adsorbed five-grass-pollen extract in seasonal rhinoconjunctivitis: a double-blind, placebo-controlled study

BACKGROUND

Calcium phosphate-adsorbed allergen extracts are used for subcutaneous immunotherapy to avoid the use of aluminium adjuvants.

OBJECTIVES

A double-blind, placebo-controlled study was performed in order to confirm the safety and assess the efficacy of a standardized five-grass-pollen extract adsorbed onto calcium phosphate for specific immunotherapy (IT).

METHODS

Twenty-nine patients with seasonal rhinoconjunctivitis were randomized to receive either the active preparation (16 patients) or placebo (13 patients), in a 1-year study. During the increasing dose phase, an extract ranging from 0.1 IR per ml to 50 IR per ml was administered at a rate of one subcutaneous injection per week until a maintenance dose was reached. The patients were assessed by symptom diary and rescue medications during seasonal exposure and specific nasal and skin reactivity before and after IT. Immunological parameters (specific IgE and IgG4 antibodies) were assessed before, during and after IT.

RESULTS

The overall symptoms score (mean AUC) was not significantly different between the IT group and the placebo group during grass-pollen exposure (49.6 vs. 56, respectively). The total medication score (mean AUC) was significantly lower in the IT group than in the placebo group (11 vs. 41, P < 0.01, Mann-Whitney U-test). The cumulative symptom/medication score was significantly lower in the IT group than in the placebo group (64.5 vs. 102.3, P < 0.05, U-test). A significant increase in nasal reactivity threshold was observed after IT in the IT group (21. 4 IR/mL before IT vs. 63.4 IR/mL after IT, P < 0.01, Wilcoxon), whereas no significant changes were observed in the placebo group (31.0 IR/mL before IT vs. 37.7 IR/mL after IT). IT induced a significant reduction in grass pollen cutaneous reactivity in the actively treated group (P < 0.001). A significant increase in serum-specific IgG4 antibody response was observed in the IT group (3.1% before IT vs. 10.1% after IT, P < 0.001). Nine patients in the IT group developed moderate immediate systemic reactions vs. two patients in the placebo group.

CONCLUSION

Specific immunotherapy with calcium phosphate-adsorbed standardized grass pollen extract was safe and effective for the treatment of patients with seasonal allergic rhinoconjunctivitis.

Pollen-specific rush immunotherapy: clinical efficacy and effects on antibody concentrations

BACKGROUND

Studies of rush immunotherapy (RIT) with standardized extracts for the treatment of seasonal pollen allergy are few, especially for birch-pollen RIT.

OBJECTIVE

The study was performed to investigate the efficacy of RIT with standardized birch- or timothy-pollen extracts. Further, the serum antibody levels were evaluated for correlation with clinical efficacy.

METHODS

This open, longitudinal study included 30 allergic patients treated with RIT and 16 allergic patients serving as a control group. The therapy was continued for 3 years and blood samples were collected at regular intervals for antibody measurements using the Pharmacia CAP System.

RESULTS

The RIT was generally well tolerated. An increase in the total and specific IgE concentrations during the early months of RIT was observed, followed by decreased levels. Specific IgG and IgG4 increased continuously for 2 years. The symptom and medication scores were significantly decreased, compared with preRIT, at both the first and third pollen seasons after the start of RIT treatment (P < .0001 and P < .001, respectively). The clinical improvement during RIT was significantly greater compared with the control group (P < .05). The decreased medication and the symptom improvement during the third year of RIT correlated with the relative decrease in specific IgE (rs = .52, P < .05) and with the specific IgG4 level before the start of RIT (rs= -.68, P < .01), respectively.

CONCLUSIONS

Our study indicates that RIT with standardized birch- or timothypollen extracts is clinically effective and safe. Measurements of specific antibody levels during treatment may be helpful in monitoring RIT.

Allergen-specific immunotherapy in birch- and grass-pollen-allergic rhinitis. I. Efficacy estimated by a model reducing the bias of annual differences in pollen counts

BACKGROUND

Evaluation of the efficacy of allergen-specific immunotherapy (IT) with pollen extracts is complicated by annual variation in pollen intensity. Our study aimed to evaluate the efficacy of birch and grass IT, taking into consideration these variations.

METHODS

After 1 year of observation, 52 patients with rhinoconjunctivitis and allergy to birch as well as grass pollen were allocated to double-blinded clustered IT with aluminum-adsorbed extract produced from either birch (Betula verrucosa) pollen or grass (PIleum pratense) pollen. After 1 year of treatment, the patients continued IT with their original extract and also received the other extract. During the three consecutive pollen seasons, the rhinoconjunctivitis symptom score and the use of antihistamines, eye-drops, and oral prednisolone were recorded. Longitudinal data analysis was used to investigate the relation between different pollen counts and the magnitude of clinical efficacy.

RESULTS

An effect of IT was found on symptom score, antihistamine intake, and eye-drop use for both birch and grass (P values <0.05). The mean reduction in symptom score/medication by IT ranged from 24% to 95%, depending on mean seasonal pollen counts. A minimum mean seasonal grass-pollen count of 20-30 pollen grains m3 was required for the efficacy of grass IT to emerge.

CONCLUSIONS

A model was developed for evaluation of efficacy in longitudinal IT studies, taking the differences in annual pollen counts into consideration. The model showed a significant beneficial role of pollen IT in rhinoconjunctivitis patients allergic to birch and grass pollen.

[Specific immunotherapy]

Increase of the prevalence of allergy these last 20 years is in part secondary to the modification of the allergenic charge of our environment. The specific immunotherapy (SIT) is the only etiologic treatment of the allergic disease and numbers of authors believe that, for the future, this treatment could change the natural history of the respiratory allergy, provided that it is realised early in the first years of life. Several experimental studies show that the process of the SIT could be the restoration of the Th1 cell/Th2 cell balance which is reversed in allergies. However, indications of SIT have to be carefully selected. The ideal indication is the single sensitized asthma, and treatment has to be started in the first years of life, at the onset of the asthmatic disease, before a definitive remodelling of the respiratory airways induced by inflammation. Subcutaneous SIT is for the moment the only effective route confirmed by several controlled trials, in particular for grass pollens, possibly for house dust, pet danders and mite allergens. Risk of syndromic effects, present all the time of the SIT protocol, can be prevented by rigorous use of the SIT according to the European consensus. The advent of recombinant allergens, in particular by complementary DNA (cDNA) modified by site-directed mutagenesis, could tip the immune response to a Th-1 like response instead of a Th-2 like response (IgE mediated) and result in a better tolerated and more efficacy immunomodulation.

Long-term clinical efficacy of grass-pollen immunotherapy

BACKGROUND

Pollen immunotherapy is effective in selected patients with IgE-mediated seasonal allergic rhinitis, although it is questionable whether there is long-term benefit after the discontinuation of treatment.

METHODS

We conducted a randomized, double-blind, placebo-controlled trial of the discontinuation of immunotherapy for grass-pollen allergy in patients in whom three to four years of this treatment had previously been shown to be effective. During the three years of this trial, primary outcome measures were scores for seasonal symptoms and the use of rescue medication. Objective measures included the immediate conjunctival response and the immediate and late skin responses to allergen challenge. Cutaneous-biopsy specimens obtained 24 hours after intradermal allergen challenge were examined for T-cell infiltration and the presence of cytokine-producing T helper cells (TH2 cells) (as evidenced by the presence of interleukin-4 messenger RNA). A matched group of patients with hay fever who had not received immunotherapy was followed as a control for the natural course of the disease.

RESULTS

Scores for seasonal symptoms and the use of rescue antiallergic medication, which included short courses of prednisolone, remained low after the discontinuation of immunotherapy, and there was no significant difference between patients who continued immunotherapy and those who discontinued it. Symptom scores in both treatment groups (median areas under the curve in 1995, 921 for continuation of immunotherapy and 504 for discontinuation of immunotherapy; P=0.60) were markedly lower than those in the group that had not received immunotherapy (median value in 1995, 2863). Although there was a tendency for immediate sensitivity to allergen to return late after discontinuation, there was a sustained reduction in the late skin response and associated CD3+ T-cell infiltration and interleukin-4 messenger RNA expression.

CONCLUSIONS

Immunotherapy for grass-pollen allergy for three to four years induces prolonged clinical remission accompanied by a persistent alteration in immunologic reactivity.

Long-term treatment with allergoid immunotherapy with Parietaria. Clinical and immunologic effects in a randomized, controlled trial

BACKGROUND

Specific immunotherapy (SIT) is a valuable treatment for respiratory allergy, and the use of chemically modified allergens (allergoids) has improved its safety, as testified by several studies. We evaluated the effects of a SIT course with an allergoid extract of Parietaria pollen in a double-blind, placebo-controlled trial.

METHODS

The study was double-blind in the first year; then it was prolonged up to 3 years with all patients on active treatment. Clinical effectiveness, safety, skin reactivity, systemic immunologic parameters, and subjective assessment were evaluated. We also had available a self-evaluation recorded in a follow-up visit 4 years after the discontinuation of SIT.

RESULTS

A significant reduction of the symptoms plus drug intake scores during the pollen seasons was observed in the patients receiving active SIT. The placebo patients, after switching to active SIT, also showed significant clinical improvement. The clinical efficacy persisted during years 2 and 3 of treatment. After year 1, the actively treated patients reported a significant subjective improvement (frequency of symptoms, P = 0.001; duration of symptoms, P = 0.024; physical performance, P = 0.043) compared with the placebo group. The self-evaluation by visual analog scale showed that all patients maintained a significant clinical improvement up to 4 years after discontinuing SIT (year 1: active=+31.6%, placebo=-15.7%; year 7: active=+35.8%, placebo=+31.3%). The systemic immunologic changes after active SIT paralleled those described elsewhere (IgE decreased from 22 to 9 and from 21 to 8 IU/ml; IgG4 increased from 43 to 87 and from 18 to 60 IU/ml). A significant decrease in skin reactivity to three different allergen concentrations was observed at year 3 compared with pretreatment values (P<0.05).

CONCLUSIONS

The investigational SIT with Parietaria appeared to be effective and safe; a 3-year course of treatment achieved a long-lasting efficacy.

Monitoring allergen immunotherapy of pollen-allergic patients: the ratio of allergen-specific IgG4 to IgG1 correlates with clinical outcome

BACKGROUND

Although allergen immunotherapy has been established as a treatment of type I allergy back in 1911, until now the underlying mechanisms have not been fully understood, nor are there any parameters which would allow one to monitor an ongoing treatment or to assess therapeutic success in the meantime.

OBJECTIVE

We wanted to define allergen-specific parameters that change due to treatment in correlation with the clinical outcome.

METHODS

We conducted a controlled study with grass pollen-allergic children and compared allergen-specific antibody titres before and 1 year after the onset of immunotherapy in contrast with untreated allergic and healthy children. Two recombinant forms of the major allergen group V of Phleum pratense (Phl p 5) served as model allergens.

RESULTS

No change in IgE levels and no significant reduction of skin prick test (SPT) reactivity were seen. On the other hand, a significant reduction of symptom scores in the treated group and a significant rise in allergen-specific IgG1, IgG2 and IgG4 due to the treatment could be observed, but in neither case could we establish a correlation between the increasing amounts of the single antibody classes and the reduction of symptom scores. But most interestingly, when comparing the ratio of IgG4 to IgG1 with the symptom scores, we found significant correlations. Nevertheless, treated allergic patients still differ considerably from healthy controls as nonatopics have hardly any measurable allergen-specific IgG antibodies and no IgE antibodies at all.

CONCLUSION

The ratio of IgG4 to IgG1 can serve as a valuable parameter that allows us to assess the success of immunotherapy already 1 year after the onset. The increase of specific IgG1 in relation to IgG4 during treatment reflects a possible influence of this subclass on the induction of tolerance towards allergens.

Immunotherapy with an alum-adsorbed Parietaria-pollen allergoid: a 2-year, double-blind, placebo-controlled study

A double-blind, placebo-controlled study was performed in order to confirm the safety, suitability, and efficacy of an alum-adsorbed Parietaria judaica-pollen allergoid, Allergovit, for allergen-specific immunotherapy. Parietaria pollen is an important cause of pollinosis, particularly in the Mediterranean zone, where it may be encountered for up to 8-9 months of the year. It is an aggressive allergen, and the doses tolerated during immunotherapy are less than those achieved with grass pollen. This factor increases the desirability of using therapeutic preparations with minimal IgE-binding activity, such as allergoids, in order to reduce the risk of side-effects and enable patients to tolerate a higher dose of allergen, thereby increasing the chances of successful specific immunotherapy. Forty patients with rhinitis and/or asthma were allocated at random to active- or placebo-treatment groups at the beginning of the study. All patients received the active preparation during the second year of the study. Immunotherapy was well tolerated by all patients and the incidence of side-effects was low. Treatment resulted in significant reductions in specific cutaneous reactivity and increases in nasal tolerance. A progressive improvement in nasal inspiratory peak flow in association with the immunotherapy indicated a reduction in nasal inflammation. These objective assessments of efficacy endorsed the results from the patients' diary cards, which indicated significant improvements in symptoms and reductions in the use of medication. The immunologic activity of the therapeutic preparation was demonstrated by the induction of a significant specific-IgG antibody response, with increases in IgG4 during the second year of treatment. We conclude that the safety and efficacy of immunotherapy with the Parietaria allergoid make it suitable for consideration in the treatment of patients with Parietaria-pollen-induced rhinitis or asthma.

Binding affinities of allergens from pollen, mites, and house dust for specific IgG subclass antibodies

The distribution and affinity of IgG subclasses against various aeroallergens were assessed by inhibition of specific antibody binding. Two parameters from the dose-response curves were taken as indicative of antibody affinity: the point of 50% inhibition and the value of the slopes on double-log plots. It was found that IgG4 antibody specific for aeroallergens (i.e., from pollens of several species of Gramineae, Olea europaea, and Parietaria judaica and from house dust) usually exhibits high affinity, except for Dermatophagoides pteronyssinus. High binding affinity was also displayed by IgG1 subclass antibodies against the allergens of O. europaea and P. judaica. Distinct IgG subclass affinity profiles were observed for the allergens of grass pollen (i.e., Holcus lanatus) and dust mites (i.e., D. pteronyssinus). These results demonstrate that IgG subclass distribution, as well as antibody affinity, depends on the nature of the sensitizing allergen.

A double-blind, placebo-controlled study of immunotherapy with grass-pollen extract Alutard SQ during a 3-year period with initial rush immunotherapy

Thirty patients with asthma and/or monosensitized allergic rhinitis caused by grass pollen whose ages ranged from 15 to 35 years were selected. Two groups were established at random: an active group and a placebo group, and a double-blind study was done on treatment with immunotherapy for a period of 3 continuous years, with initiation doses administered according to the rush immunotherapy technique. Grass-pollen allergen extract Alutard SQ and histamine as a placebo were used. The objective parameters of efficacy evaluated were end-point cutaneous tests, conjunctival provocation, bronchial provocation, and symptom/medication scores, as well as specific immunoglobulin determinations. The statistical evaluation of the results was significant for the differences existing between the initial and final time of the active group, and there were significant differences between the two groups for all of the parameters considered. We found no relationship between clinical improvement and the range of specific immunoglobulin E values. Regarding the safety of the treatment, systemic adverse effects were manifested only in the initial phase (rush immunotherapy), and were easily controlled by treatment. We conclude that the efficacy and safety of immunotherapy with grass pollen make it possible to consider this treatment fundamental in these patients.

Peptide-mediated regulation of the allergic immune response

A major key to successful immunotherapy may depend on altering the qualitative nature of the immune response in allergic patients. In this review we examine how immune responses to environmental allergens are regulated, and the mechanisms used by the immune system to prevent allergic sensitization. We also discuss future prospects of using allergen-derived peptides in immunotherapy and the possibility of 'reprogramming' the immune responses by immunizing under conditions that promote Th1 responses instead of Th2 responses.

Local nasal immunotherapy with extract in powder form is effective and safe in grass pollen rhinitis: a double-blind study

BACKGROUND

Local nasal immunotherapy has been studied, by means of an extract in powder form, in patients with allergic rhinitis caused by grass pollen.

METHODS

Thirty-two patients allergic to grass were studied for 37 weeks in a double-blind controlled trial. Subjects were selected on the basis of a positive history, skin test result, RAST finding, and result of intranasal challenge to grass pollen. Two 16-patient groups were randomly assigned to active or placebo treatment. The treatment lasted 26 weeks (14 for the build-up phase, 12 for the maintenance period).

RESULTS

No significant differences were observed in nasal symptoms during the treatment. During the pollen season the mean weekly symptom and medication scores were significantly lower in the treated group, compared with the control group, even considering each allergic symptom separately. Moreover, only in the treated group was a significant increase of specific nasal threshold to grass pollen observed after treatment.

CONCLUSIONS

This study indicates that local nasal immunotherapy with allergen in powder form can be a suitable alternative to the traditional subcutaneous immunotherapy in terms of clinical efficacy and safety in grass-allergic rhinitis.

A double-blind, placebo-controlled study of immunotherapy with an alginate-conjugated extract of Parietaria judaica in patients with Parietaria hay fever

A double-blind, placebo-controlled study was conducted to evaluate the efficacy and safety of immunotherapy (IT) with a partially purified alginate-conjugated extract of Parietaria judaica (Conjuvac Parietaria, Dome/Hollister-Stier) in patients suffering from rhinoconjunctivitis caused by Parietaria pollen. Eighteen patients (10 women, 8 men, mean age 35 years) received active treatment and 17 (10 women, 7 men, mean age 42.5 years) received placebo. Actively treated patients had significantly lower nasal symptom/medication scores (running nose P = 0.0087 and sneezing P = 0.048) during the Parietaria pollen season. Significant decreases in specific skin (P < 0.01), nasal (P < 0.05), and conjunctival (P < 0.01) reactivity to the Parietaria extract and significant increases of specific IgG (P < 0.001), IgG1 (P < 0.001), and IgG4 (P < 0.001) in actively treated patients, but not in placebo, were found. IT was well tolerated, the active extract inducing five mild systemic reactions (four rhinitis and one urticaria) and placebo two (rhinitis). A significant correlation was found between low skin reactivity and high specific IgG (P = 0.0002) and IgG4 (P = 0.036). These findings indicate that IT with a partially purified P. judaica extract is an effective and safe treatment for Parietaria pollen allergy. The correlation between low immediate skin reactivity and high specific IgG and IgG4 suggests that, at least in the studied cutaneous model, these antibodies may exert a blocking effect.

Safety considerations in assessing the role of immunotherapy in allergic disorders

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