Clinical efficacy and immunological mechanisms of sublingual and subcutaneous immunotherapy in asthmatic/rhinitis children sensitized to house dust mite: an open randomized controlled trial

Background In children, the clinical efficacy and immunological mechanisms of sublingual immunotherapy (SLIT) compared with subcutaneous immunotherapy (SCIT) is still to be elucidated. Objectives To compare SLIT, SCIT and pharmacotherapy in relation to clinical efficacy and immunological mechanisms that govern its effect in asthmatic/rhinitis children who were sensitized to house dust mite (HDM). Methods In this single centre, prospective, randomized, controlled, open labelled, three parallel group trial, 48 patients mono‐sensitized to HDM were randomized to receive either SLIT (n=16), SCIT (n=16) or pharmacotherapy alone (n=16). Symptom, medication and visual analogue score (VAS) were collected and bronchial‐nasal hyper‐reactivity, skin prick tests, total‐specific IgE were performed at baseline and 12 months after treatment. In addition, peripheral blood mononuclear cells were cultured with recombinant Der p 1 and Bet v 1 extracts and allergen‐specific IL‐4, IL‐5, IL‐13, IFN‐γ, IL‐10, and TGF‐β secretions were measured. Results SLIT and SCIT demonstrated a significant reduction of total rhinitis and asthma symptom score, total medication score, VAS and skin reactivity to HDM (P<0.05) when compared with pharmacotherapy. A significant reduction of serum‐specific HDM‐IgE in SCIT and SLIT were observed. Moreover, titrated nasal provocative dose significantly increased in both immunotherapy groups when compared with the pharmacotherapy group. No adverse effects were reported in SLIT, while two patients demonstrated serious adverse events in SCIT. After 1 year of treatment, Der p 1‐driven IL‐10 significantly increased in SLIT compared with pharmacotherapy, whereas Bet v 1‐driven TGF‐β (negative control) increased significantly in SLIT only. No changes were observed for Th1–Th2 cytokines. Conclusion Both SLIT and SCIT demonstrated clinical improvement compared with pharmacotherapy in asthma/rhinitis children sensitized to HDM.     

Shorter Dosing Intervals of Sublingual Immunotherapy Lead to More Efficacious Treatment in a Mouse Model of Allergic Inflammation

Current day practice of sublingual immunotherapy (SLIT) includes varying modalities of treatment that differ with regard to formulation, dosing and administration regimens. The aim of this study was to explore the importance of the dosing intervals in SLIT. The immunological effect of increased SLIT dosing frequency was tested in a mouse model of allergic inflammation. Mice sensitized to Phleum pratense (Phl p) were SLIT‐treated with the same weekly cumulative dose administered with different administration frequencies. A SLIT sham‐treated group was also included. All mice were challenged intra‐nasally with Phl p extract following SLIT. Local and systemic cytokine production, eosinophil infiltration into airways and the development of Phl p‐specific antibody responses were determined. Higher frequency of sublingual administration of allergen extract has a profound positive impact on the effect of SLIT, measured as induction of IgG and IgA antibodies. The once daily SLIT was the only treatment regimen being able to reduce all systemic Th2 cytokines and systemic IgE antibody responses when compared to sham‐treated mice after the intra‐nasal challenge period. The group receiving SLIT with the highest frequency of administration had the most pronounced effect of the treatment. In the same group, there was also a higher degree of protection against increase in IgE antibody levels after intra‐nasal challenge with the allergen, our data demonstrate that a once daily regimen is more efficacious than regimens where SLIT, with the same weekly cumulative allergen dose, is administered with longer intervals but higher doses.     

Inhibition of CD23‐dependent facilitated allergen binding to B cells following vaccination with genetically modified hypoallergenic Bet v 1 molecules

Background Vaccination with hypoallergenic recombinant Bet v 1 derivatives (Bet v 1 fragments and Bet v 1 trimer) is associated with the induction of IgG antibodies specific to natural Bet v 1. Objective To investigate whether IgG antibodies induced following vaccination with genetically modified hypoallergenic Bet v 1 derivatives are able to inhibit IgE‐facilitated binding of allergen‐IgE complexes to B cells. Methods Sera from 46 patients obtained before and after subcutaneous vaccination with Bet v 1 trimer (n=14), Bet v 1 fragments (n=11) or placebo (n=21) were incubated with recombinant (r) Bet v 1 and an indicator serum (IS) from a birch pollen‐allergic patient with high CD23 binding capacity. Bet v 1 immune complexes were added to a CD23‐expressing B cell line and co‐operative binding of Bet v1‐IgE complexes to CD23 was measured with a polyclonal anti‐IgE FITC antibody using a bio‐functional cellular flow cytometric assay. Results When sera from patients vaccinated with rBet v 1 derivatives were incubated with Bet v 1 and the IS, a reduction of IgE binding to CD23 was observed. This effect was not seen when sera from placebo‐treated patients were used. The decrease in CD23/IgE binding was statistically significant in the trimer group [pre‐ vs. post‐specific immunotherapy (SIT): P=0.02; trimer vs. placebo: P<0.04] but not in the Bet v 1 fragments‐treated group. Trimer‐treated patients had higher levels of Bet v 1‐specific IgG than fragment‐treated patients. The degree of inhibitory activity of IgE‐facilitated allergen binding correlated with Bet v 1‐specific IgG levels following SIT (R=0.492; P=0.012). Conclusion Vaccination with both recombinant Bet v 1 derivatives induces Bet v 1‐specific IgG antibodies, which are able to inhibit the co‐operative binding of allergen‐IgE complexes to CD23, and may thereby reduce allergen‐specific T cell responses. Cite this as: I. Pree, M. H. Shamji, I. Kimber, R. Valenta, S. R. Durham and V. Niederberger, Clinical & Experimental Allergy, 2010 (40) 1346–1352.     

Efficacy,safety, and immunological effects of a 2‐year immunotherapy with Depigoid® birch pollen extract: a randomized,double‐blind,placebo‐controlled study

Background Rhinoconjunctivitis due to birch pollen sensitization is common in Northern Europe. A depigmented polymerized birch pollen extract – Depigoid^® has been developed for immunotherapy. Objective To evaluate its clinical efficacy, safety, and effects on immunological parameters. Methods Sixty‐one patients aged 7–69 years were included in a randomized, double‐blind, placebo‐controlled trial of subcutaneous immunotherapy (SCIT) using depigmented polymerized birch pollen extract. SCIT consisted of four increasing doses at 7‐day intervals, followed by maintenance injections of 500 DPP (corresponding to 30 μg Bet v1 before depigmentation) at 6‐week intervals for 18 months. The primary outcome was the combined symptom and medication score during the 2006 birch pollen season. The frequency of peripheral blood mononuclear cells (PBMC)producing IL‐4, IL‐10, IL‐12, and IL‐13 was assessed in a subgroup of patients by ELISPOT assay. Results After 18 months of treatment, the median combined symptom and medication score (upper/lower quartile) of treated patients was significantly lower than those on placebo: 8.0 (5.8–10.3) and 12.6 (8.6–16.2), respectively (P=0.004). Systemic reactions occurred in 29 patients (12 active, 17 placebo), were grades 1 or 2, and none required specific treatment. After 18 months of treatment, mean serum concentrations of specific IgE increased significantly in both groups (P<0.0001) whereas serum concentrations of both specific IgG1 and IgG4 only increased significantly in the SCIT group (P=0.002) and not in the placebo group. The seasonal increase in numbers of IL‐4‐ and IL‐13‐producing PBMC was blunted by immunotherapy. Conclusions SCIT with depigmented polymerized birch pollen extract significantly reduced symptom and medication scores when compared with the placebo, was well tolerated, and resulted in immunological changes comparable with those of native pollen extracts. Cite this as: A.‐S. Höiby, V. Strand, D.S. Robinson, A. Sager and S. Rak, Clinical & Experimental Allergy, 2010 (40) 1062–1070.     

Sublingual allergen immunotherapy in HIV‐positive patients

HIV infection is a relative contraindication for allergic immunotherapy (AIT). In the last decade, highly active antiretroviral therapy (HAART) has improved the immune function and life expectancy in HIV‐infected patients whose respiratory allergic incidence is similar to the general population. We evaluated the safety and clinical effectiveness of sublingual immunotherapy in a group of grass pollen‐allergic HAART‐treated HIV‐positive patients. Thirteen patients received sublingual immunotherapy (SLIT) tablet (Oralair, Stallergenes©) and symptomatic therapy and were compared with nine patients receiving symptomatic therapy alone. Clinical benefits were evaluated by the analysis of total combined score (TCS), sum of symptom–medication score, and a quality of life (QoL) questionnaire. HIV viral load and peripheral TCD4 lymphocytes were analyzed at the beginning and at the end of the study. Clinical efficacy data showed a significant improvement in SLIT‐treated patients compared to controls (TCS: P = 0.0001; QoL: P = 0.03). We did not observe any significant alteration of TCD4 cell counts and viral load (VL) in both groups. Our preliminary data showed that SLIT therapy in viro‐immunological controlled HAART treated HIV positive patients was efficacious, safe and well tolerated.     

Eosinophils in bronchial mucosa of asthmatics after allergen challenge: effect of anti-IgE treatment

Background: Anti‐IgE, omalizumab, inhibits the allergen response in patients with asthma. This has not been directly related to changes in inflammatory conditions. We hypothesized that anti‐IgE exerts its effects by reducing airway inflammation. To that end, the effect of anti‐IgE on allergen‐induced inflammation in bronchial biopsies in 25 patients with asthma was investigated in a randomized, double‐blind, placebo‐controlled study. Methods: Allergen challenge followed by a bronchoscopy at 24 h was performed at baseline and after 12 weeks of treatment with anti‐IgE or placebo. Provocative concentration that causes a 20% fall in forced expiratory volume in 1 s (PC₂₀) methacholine and induced sputum was performed at baseline, 8 and 12 weeks of treatment. Changes in the early and late responses to allergen, PC₂₀, inflammatory cells in biopsies and sputum were assessed. Results: Both the early and late asthmatic responses were suppressed to 15.3% and 4.7% following anti‐IgE treatment as compared with placebo (P < 0.002). This was paralleled by a decrease in eosinophil counts in sputum (4–0.5%) and postallergen biopsies (15–2 cells/0.1 mm²) (P < 0.03). Furthermore, biopsy IgE+ cells were significantly reduced between both the groups, whereas high‐affinity IgE receptor and CD4+ cells were decreased within the anti‐IgE group. There were no significant differences for PC₂₀ methacholine. Conclusion: The response to inhaled allergen in asthma is diminished by anti‐IgE, which in bronchial mucosa is paralleled by a reduction in eosinophils and a decline in IgE‐bearing cells postallergen without changing PC₂₀ methacholine. This suggests that the benefits of anti‐IgE in asthma may be explained by a decrease in eosinophilic inflammation and IgE‐bearing cells.     

Depletion of CD4+CD25+ T cells switches the whey‐allergic response from immunoglobulin E‐ to immunoglobulin free light chain‐dependent

Background Symptoms of allergy are largely attributed to an IgE‐mediated hypersensitivity response. However, a considerable number of patients also exhibit clinical features of allergy without detectable systemic IgE. Previous work showed that Ig‐free light chains (IgLC) may act as an alternate mechanism to induce allergic responses. CD4⁺CD25⁺ T cells are crucial in the initiation and regulation of allergic responses and compromised function might affect the response to allergens. Objective To examine the contribution of CD4⁺CD25⁺ T cells and IgLC towards the whey‐allergic response. Methods Mice were sensitized orally with whey using cholera toxin as an adjuvant. CD25⁺ T cells were depleted in vivo using a CD25 mAb. The acute allergic skin response to whey and ex vivo colon reactivity was measured in the presence or absence of F991, a specific inhibitor of IgLC. Serum whey‐specific antibodies and IgLC in serum and mesenteric lymph node (MLN) supernatants were measured. Depletion of CD4⁺CD25⁺ T cells was confirmed in the spleen. Results Anti‐CD25 treatment strongly reduced whey‐specific antibody levels and resulted in a partial depletion of effector T cells and a major depletion of Foxp3⁺ regulatory T cells. Surprisingly, despite the abolished specific IgE response, the acute allergic skin response to whey was not affected. IgLC levels were enhanced in the serum and MLN supernatants of CD25‐depleted sensitized mice. F991 inhibited the acute skin response and colon hyperreactivity in anti‐CD25‐treated mice, indicating that these responses were mainly IgLC dependent. Conclusions Depletion of CD4⁺CD25⁺ T cells resulted in a switch from an IgE‐ to an IgLC‐dependent acute skin response and functional hyperresponsiveness of the colon. Our data suggest that CD25⁺ T cells play a crucial role in balancing cow's milk allergy between IgE and IgE‐independent responses and both mechanisms might play a role in allergic responses to the same allergen. Cite this as: B. C. A. M. van Esch, B. Schouten, B. R. J. Blokhuis, G. A. Hofman, L. Boon, J. Garssen L. M. J. Knippels, L. E. M. Willemsen and F. A. Redegeld, Clinical & Experimental Allergy, 2010 (40) 1414–1421.     

Absence of systemic immunologic changes during dose build-up phase and early maintenance period in effective specific sublingual immunotherapy in children

Background Sublingual immunotherapy (SLIT) has been reported to be a safe treatment for inhalant allergies in children. Yet the immunologic mechanisms resulting in clinical improvement are poorly understood. Objective To identify early systemic immunologic changes during the first 8 weeks of clinically effective SLIT to grass pollen, tree pollen or house dust mite in paediatric patients with allergic rhinoconjunctivitis and/or asthma. Methods Peripheral blood mononuclear cells and plasma samples of 13 children with reduced symptoms after 1 year of SLIT were obtained before therapy and at 2 and 8 weeks after the initiation of SLIT. Allergen‐specific lymphocyte proliferation assays were performed, and allergen‐induced cytokine production (IL‐2, IL‐4, IL‐10, IFN‐γ, and TGF‐β₁) was measured by ELISA and flow cytometry. Allergen‐specific IgE, IgG1, IgG4, and IgA levels in plasma samples were determined in ELISA. Results During the first 8 weeks of successful SLIT, allergen‐specific lymphoproliferation (n=13) as well as levels of allergen‐specific intracellular (n=8) and secreted cytokines (n=9) did not change significantly. In addition, no alterations in levels of allergen‐specific Igs (n=7) were observed. Conclusion We could not find any early systemic immunologic changes during the first 8 weeks of clinically effective SLIT to inhalant allergens in paediatric patients with allergic rhinoconjunctivitis and/or asthma.     

Basophil allergen threshold sensitivity,CD‐sens,is a measure of allergen sensitivity in asthma

Background Allergic asthma is IgE‐mediated and the IgE‐sensitisation is usually demonstrated by skin prick tests (SPT) and IgE antibody determinations in serum. The SPT and IgE‐antibody values do not directly predict if the allergy clinically contributes to the asthma. There is therefore a need for new objective tests that may indicate the clinical importance of an IgE‐sensitisation. Objective To evaluate basophil allergen threshold sensitivity (CD‐sens) as a measure of allergen sensitivity in allergic asthma. Methods Twenty‐six subjects with stable, intermittent allergic asthma were tested with SPT and spirometry, and methacholine and allergen inhalation challenges to determine methacholine PD₂₀ (provocative dose causing a 20% drop in forced expiratory volume in 1 s) and allergen PD₂₀. The results were compared with CD‐sens and serological parameters, i.e. IgE‐ and IgG4 antibodies to the relevant allergens. Results A significant correlation was found between CD‐sens and allergen PD₂₀ (P=0.01; r=0.49; n=26) as well as between CD‐sens and the ratio of allergen PD₂₀ to methacholine PD₂₀ (P=0.007; r=0.52; n=26). In patients with a moderate to low degree of bronchial hyperresponsiveness there was an excellent correlation (P=0.0001; r=0.88, n=13) between CD‐sens and allergen sensitivity. No relation to either allergen PD₂₀ or the ratio was found for basophil allergen reactivity measured as CD63 up‐regulation at high concentrations of the respective allergen. Conclusions and Clinical Relevance CD‐sens was found to be an objective marker of airway allergen sensitivity in stable allergic asthmatics, that may be used to predict airway responsiveness when bronchial challenge tests cannot be performed. Cite this as: B. Dahlén, A. Nopp, S. G. O. Johansson, M. Eduards, M. Skedinger and J. Adédoyin, Clinical & Experimental Allergy, 2011 (41) 1091–1097.     

Intranasal administration of allergen increases specific IgE whereas intranasal omalizumab does not increase serum IgE levels—A pilot study

Background

Administration of the therapeutic anti‐IgE antibody omalizumab to patients induces strong increases in IgE antibody levels.

Objective

To investigate the effect of intranasal administration of major birch pollen allergen Bet v 1, omalizumab or placebo on the levels of total and allergen‐specific IgE in patients with birch pollen allergy.

Methods

Based on the fact that intranasal allergen application induces rises of systemic allergen‐specific IgE, we performed a double‐blind placebo‐controlled pilot trial in which birch pollen allergic subjects were challenged intranasally with omalizumab, placebo or birch pollen allergen Bet v 1. Total and allergen‐specific IgE, IgG and basophil sensitivity were measured before and 8 weeks after challenge. For control purposes, total, allergen‐specific IgE levels and omalizumab‐IgE complexes as well as specific IgG levels were studied in subjects treated subcutaneously with either omalizumab or placebo. Effects of omalizumab on IgE production by IL‐4/anti‐CD40‐treated PBMCs from allergic patients were studied in vitro.

Results

Intranasal challenge with Bet v 1 induced increases in Bet v 1‐specific IgE levels by a median of 59.2%, and this change differed significantly from the other treatment groups (P = .016). No relevant change in allergen‐specific and total IgE levels was observed in subjects challenged with omalizumab. Addition of omalizumab did not enhance IL‐4/anti‐CD40‐induced IgE production in vitro. Significant rises in total IgE (mean IgE before: 131.83 kU/L to mean IgE after: 505.23 kU/L) and the presence of IgE‐omalizumab complexes were observed after subcutaneous administration of omalizumab.

Conclusion

Intranasal administration of allergen induced rises of allergen‐specific IgE levels, whereas intranasal administration of omalizumab did not enhance systemic total or allergen‐specific IgE levels.     

Clinical efficacy of sublingual and subcutaneous birch pollen allergen-specific immunotherapy: a randomized, placebo-controlled, double-blind, double-dummy study

BACKGROUND: Both sublingual allergen-specific immunotherapy (SLIT) and subcutaneous immunotherapy (SCIT) have a documented clinical efficacy, but only few comparative studies have been performed. OBJECTIVE: To investigate the clinical efficacy of SLIT vs SCIT and secondary to compare SLIT and SCIT with placebo and to evaluate the relative clinical efficacy in relation to systemic side-effects. METHODS: A 3-year randomized, placebo-controlled, double-blind, double-dummy study including 71 adult birch pollen hay fever patients treated for two consecutive years after a baseline year. Allocation to treatment groups was based on disease severity in the baseline season, gender and age. RESULTS: Clinical efficacy was estimated in 58 patients completing the first treatment year by subtracting baseline data and by calculating the ratio first treatment season vs baseline. SLIT diminished the median disease severity to one-half and SCIT to one-third of placebo treatment. No statistical significant difference between the two groups was observed. Both for symptoms and medication scores actively treated patients showed statistically significant and clinical relevant efficacy compared with placebo. SLIT treatment only resulted in local mild side-effects, while SCIT resulted in few serious systemic side-effects. CONCLUSION: Based on the limited number of patients the clinical efficacy of SLIT was not statistically different from SCIT, and both treatments are clinically effective compared with placebo in the treatment of birch pollen rhinoconjunctivitis. The lack of significant difference between the two treatments does not indicate equivalent efficacy, but to detect minor differences necessitates investigation of larger groups. Due to the advantageous safety profile SLIT may be favored.     

Time course of serum inhibitory activity for facilitated allergen–IgE binding during bee venom immunotherapy in children

Background Immunotherapy for bee venom allergy is effective and provides long‐term protection. Venom‐specific IgG4 levels are increased but with no correlation with clinical improvement. Following grass pollen immunotherapy, elevation of antigen‐specific IgG4 is accompanied by increases in IgG‐dependent serum inhibitory activity for IgE‐facilitated binding of allergen–IgE complexes to B cells. As this ‘functional’ assay of inhibitory antibodies may be more predictive of clinical efficacy, we investigated the time course of serum inhibitory activity for IgE‐facilitated antigen binding during venom immunotherapy (VIT) in children and following 2 years of VIT withdrawal. Methods Ten bee venom‐allergic children (mean age: 9.3 years; m/f, 7/3) with moderate to severe allergic reactions to bee stings received VIT. A separate group of seven children (mean age: 14 years; m/f, 5/2) were investigated 2 years after VIT withdrawal. Ten age‐ and gender‐matched children served as non‐allergic controls. Allergen‐specific serum IgG4 and IgE levels were measured by ELISA at baseline, after 2 years of VIT and 2 years after VIT withdrawal. Serum inhibitory activity was assessed using the facilitated‐allergen binding (FAB) assay. Results Sera obtained during VIT significantly inhibited allergen–IgE binding to B‐cells (pre‐treatment=104±23%; 2 years=46±15%; P<0.001) when compared with sera obtained after treatment withdrawal and sera from normal controls. In parallel to FAB inhibition during VIT, significantly higher IgG4 levels were noted after immunotherapy (pre‐treatment=8.6±2.3 AU; 2 years=26.7±3.5 AU; P<0.001) compared with those observed after withdrawal and in the controls. In contrast, progressively lower IgE concentrations were observed compared with pre‐treatment (44±7 AU) in sera obtained after 2 years of VIT (25±5 AU; P<0.01) and 2 years following the withdrawal of VIT (10±3 AU; P<0.05). Conclusions In contrast to grass pollen immunotherapy, the persistent decline in venom‐specific IgE levels, rather than serum inhibitory activity for FAB, may be more relevant for long‐term clinical efficacy of VIT.     

EAACI Guidelines on allergen immunotherapy: IgE‐mediated food allergy

Food allergy can result in considerable morbidity, impairment of quality of life, and healthcare expenditure. There is therefore interest in novel strategies for its treatment, particularly food allergen immunotherapy (FA‐AIT) through the oral (OIT), sublingual (SLIT), or epicutaneous (EPIT) routes. This Guideline, prepared by the European Academy of Allergy and Clinical Immunology (EAACI) Task Force on Allergen Immunotherapy for IgE‐mediated Food Allergy, aims to provide evidence‐based recommendations for active treatment of IgE‐mediated food allergy with FA‐AIT. Immunotherapy relies on the delivery of gradually increasing doses of specific allergen to increase the threshold of reaction while on therapy (also known as desensitization) and ultimately to achieve post‐discontinuation effectiveness (also known as tolerance or sustained unresponsiveness). Oral FA‐AIT has most frequently been assessed: here, the allergen is either immediately swallowed (OIT) or held under the tongue for a period of time (SLIT). Overall, trials have found substantial benefit for patients undergoing either OIT or SLIT with respect to efficacy during treatment, particularly for cow's milk, hen's egg, and peanut allergies. A benefit post‐discontinuation is also suggested, but not confirmed. Adverse events during FA‐AIT have been frequently reported, but few subjects discontinue FA‐AIT as a result of these. Taking into account the current evidence, FA‐AIT should only be performed in research centers or in clinical centers with an extensive experience in FA‐AIT. Patients and their families should be provided with information about the use of FA‐AIT for IgE‐mediated food allergy to allow them to make an informed decision about the therapy.     

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.     

Transaldolases are novel and immunoglobulin E cross‐reacting fungal allergens

Background Mould‐induced atopic respiratory diseases are a worldwide problem. Characterization of fungal allergens is of major clinical importance. Objective We identified a novel transaldolase family allergen of Cladosporium and Penicillium species. Methods Fungal allergens were identified by immunoblotting, peptide mass mapping and partial sequencing, cDNA cloning and IgE epitope mapping. Results A 36.5 kDa IgE‐binding component in a partially purified C. cladosporioides preparation was identified. Mass spectrometric analyses suggest that this novel IgE‐reacting allergen is a transaldolase. A corresponding full‐length 1246 bp cDNA encoding a polypeptide of 325 residues was isolated. The newly identified transaldolase allergen has been designated as Cla c 14.0101. The cDNA encoding the Pencillium chrysogenum transaldolase was isolated by RT‐PCR according to the cDNA sequence encoding a P. chrysogenum Wisconsin 54‐1255 hypothetical protein. The purified rCla c 14.0101 protein reacted with IgE antibodies in 10 (38%) of 26 Cladosporium cladosporioides‐sensitized asthmatic patients. Nine of the 10 rCla c 14.0101‐positive sera have IgE binding against the recombinant Penicillium transaldolase (rPen ch 35.0101). Among the eight fungal transaldolase‐positive sera tested, three showed IgE binding against the recombinant human transaldolase. To determine cross‐reactivity between the Cladosporium and Penicillium fungi, IgE cross‐reactivity was detected between these two fungal transaldolase allergens by inhibition assays. Both the N‐ and the C‐terminal fragments of Cla c 14.0101 were recognized by IgE antibodies. The C‐terminal IgE‐reacting determinant was narrowed down to a region encompassing Thr257 to Ser278 of Cla c 14.0101. It was mapped onto a loop‐like structure of a 3D model constructed for Cla c 14.0101. Conclusion and Clinical Relevance We identified transaldolase as a novel and IgE cross‐reactive allergen family of C. cladosporioides and P. chrysogenum. In addition, an IgE‐reacting fragment (Thr257 to Ser278) was pinpointed to a loop‐like structure on Cla c 14.0101. Results obtained provide important information in clinical mould allergy. Cite this as: H. Chou, M. F. Tam, C.‐H. Chiang, C.‐T. Chou, H.‐Y. Tai and H.‐D. Shen, Clinical & Experimental Allergy, 2011 (41) 739–749.     

Increase of allergen‐specific immunoglobulin E antibodies from 1973 to 1994 in a Finnish population and a possible relationship to Helicobacter pylori infections1

Background The prevalence of atopic diseases – hayfever, asthma and eczema – has increased over the past decades. The increase may be associated with decreased rates of infections such as measles, hepatitis A, tuberculosis, toxoplasmosis, and, as recently suggested, Helicobacter pylori gastritis. Objective Since the increase of atopy has been mainly based on clinical studies, we wanted to study the prevalence of allergen‐specific Immunoglobulin (Ig)E antibodies in two cross‐sectional, adult population‐based serum samples two decades apart. Since the sera had been tested for H. pylori antibodies, we also had a chance to look for a possible relationship between these two findings. Methods We determined the prevalence rate of allergen‐specific serum IgE antibodies against birch and timothy pollen, and cat and dog epithelium allergens by the radioallergosorbent test in a 15–54‐years‐old Finnish population using 326 sera collected in 1973 and 319 sera collected in 1994 from randomly selected subjects. Results From 1973 to 1994 allergen‐specific IgE prevalence rates and IgE antibody levels rose. In 1994, the prevalence rate of positive findings in 15–24‐year‐old population had increased from 11 to 38% (3.5‐fold increase, P = 0.0001, OR 5.12, CI 95% 2.32–11.3). In older 10‐year age groups similar trends did not reach significance, but the overall change was significant with all three cut‐off levels of allergen‐specific IgE analysed. The percentage of IgE‐positive persons rose mainly in the subgroup with no H. pylori antibodies. In 1994 21% of the H. pylori‐negative subjects had IgE antibodies compared with 5% of the H. pylori‐positive subjects (in 1973 11% in both subgroups). Conclusions IgE‐based evidence for an increase in IgE‐mediated allergy was uncovered. The increase occurred mainly in the subgroup with no antibodies to H. pylori, which support the hypothesis that H. pylori could be one of the microbes counteracting atopy.     

A bright future for sublingual immunotherapy--contra

Defining the role of sublingual immunotherapy (SLIT) for the treatment of allergic rhinoconjunctivitis and allergic asthma is hampered for various reasons: Heterogeneity in study designs, different allergen extracts and dosages, imperfect assessment strategies and partially inconclusive results. A number of questions need to be addressed before replacing subcutaneous immunotherapy (SCIT) by the sublingual route: Ideal dose, treatment duration, magnitude of improvement, modification of the immune response, long-term and preventive effects. At present, SLIT might be used in adults with pollen related rhinoconjunctivitis, particularly if SCIT is not suitable for the patient (i.e. systemic effects). Only few data support SLIT for house dust mite allergy or bronchial asthma. Due to a lack of convincing results SLIT for children should only be applied in controlled studies and not in the daily routine. A more substantiated and conclusive judgment of SLIT is possibly warranted in a few years, when more studies with larger patient groups have addressed open questions concerning SLIT.     

A randomized,double‐blind,placebo‐controlled,dose‐finding trial with Lolium perenne peptide immunotherapy

Background

A novel subcutaneous allergen immunotherapy formulation (gpASIT+?) containing Lolium perenne peptides (LPP) and having a short up‐dosing phase has been developed to treat grass pollen–induced seasonal allergic rhinoconjunctivitis. We investigated peptide immunotherapy containing the hydrolysate from perennial ryegrass allergens for the optimum dose in terms of clinical efficacy, immunogenicity and safety.

Methods

This prospective, double‐blind, placebo‐controlled, phase IIb, parallel, four‐arm, dose‐finding study randomized 198 grass pollen–allergic adults to receive placebo or cumulative doses of 70, 170 or 370 μg LPP. All patients received weekly subcutaneous injections, with the active treatment groups reaching assigned doses within 2, 3 and 4 weeks, respectively. Efficacy was assessed by comparing conjunctival provocation test (CPT) reactions at baseline, after 4 weeks and after completion. Grass pollen–specific immunoglobulins were analysed before and after treatment.

Results

Conjunctival provocation test (CPT) response thresholds improved from baseline to V7 by at least one concentration step in 51.2% (170 μg; P = .023), 46.3% (370 μg), and 38.6% (70 μg) of patients receiving LPP vs 25.6% of patients receiving placebo (modified per‐protocol set). Also, 39% of patients in the 170‐μg group became nonreactive to CPT vs 18% in the placebo group. Facilitated allergen‐binding assays revealed a highly significant (P < .001) dose‐dependent reduction in IgE allergen binding across all treatment groups (70 μg: 17.1%; 170 μg: 18.8%; 370 μg: 26.4%). Specific IgG₄ levels increased to 1.6‐fold (70 μg), 3.1‐fold (170 μg) and 3.9‐fold (370 μg) (mPP).

Conclusion

Three‐week immunotherapy with 170 μg LPP reduced CPT reactivity significantly and increased protective specific antibodies.