Years Of Allergen-specific Immunotherapy Research Articles

The impact of allergen specific immunotherapy with house dust mite allergens on natural course of asthma in children

Objective . To assess the dynamics of bronchial asthma (BA) and allergic rhinitis (AR) caused by house dust mites (HDM) in children during 3 years of allergen specific immunotherapy (ASIT) with HDM allergens and 1 year after treatment cessation. Research methods . 50 patients completed an open, prospective, controlled 5-year study. 25 patients of the main group with BA and sensitization to HDM underwent a year of preliminary observation, 3 years of ASIT with HDM allergens, and 1 year of follow-up: 16 boys (64%), 9 girls (36%), 5 years to 13 years (8.3 [6.7; 11.5]) at inclusion. The control group of 25 patients, who did not receive ASIT, was selected as pairs copies. At inclusion, the concentration of periostin and thymic stromal lymphopoietin (TSLP) in blood serum and nasal material was determined in all patients. The dynamics BA and AR was assessed based on the total index of symptoms and medications for each year of observation. Results . During 3 years of treatment, a significant clinical effect of ASIT was formed, which persisted for 1 year of follow-up after the end of ASIT. At the end of the follow-up year, the overall index of symptoms and medications was 8.77 ± 1.06 points in the ASIT group and 22.01 ± 2.18 points in the control group (p=0.00001). The concentration of periostin before the start of treatment did not affect the effectiveness and features of the ASIT treatment course. A high serum TSLP concentration (>750 pg/ml) is characteristic of the subgroup with a higher incidence of adverse events associated with ASIT; the final effectiveness of ASIT does not depend on the concentration of this marker. Conclusion . ASIT with HDM sublingual drops is the method of first choice in the treatment of children with BA and AR, in cases where the role of HDM allergens in the genesis of the disease has been proven. A successful ASIT has a prolonged effect (at least 1 year of follow-up), which indicates the possibility of changing the natural course of asthma in children. The study of biomarkers does not allow us to predict the effectiveness of ASIT.

Interleukin 10 and transforming growth factor-beta 1 plasma levels in atopic dogs before and during immunotherapy.

Human studies suggest that the cytokines, interleukin 10 (IL-10) and transforming growth factor-beta 1 (TGF-ß1) may play an important role in allergen-specific immunotherapy (ASIT). However, there is little known about the function of these cytokines in atopic dogs. This study compared the plasma levels of IL-10 and TGF-ß1 in atopic and control dogs and investigated their changes during different ASIT approaches. A total of 54 atopic and 32 control dogs were included. Immunotherapy was performed in 30 atopic dogs. The dogs undergoing immunotherapy were allocated to four groups of different ASIT approaches (namely subcutaneous, intralymphatic, sublingual ASIT and subcutaneous ASIT with recombinant allergens). Blood samples were collected at four timepoints throughout the one year of ASIT. Canine atopic dermatitis extent and severity index, pruritus visual analogue scale and medication score were recorded at each timepoint. Commercially available ELISA kits were used to quantify IL-10 and TGF-ß1 in plasma. There was no significant difference in IL-10 and TGF-ß1 between atopic and control dogs. The IL-10 levels were significantly increased in the intralymphatic group at the end of the study. No significant differences were found in the other groups for both IL-10 and TGF-ß1. The findings of this work suggest that IL-10 and TGF-ß1 cannot be used to monitor the course of the disease during ASIT.

Trained immunity and tolerance in innate lymphoid cells, monocytes, and dendritic cells during allergen-specific immunotherapy

Despite the efficacy of allergen-specific immunotherapy (AIT), the role of trained immunity and tolerance in this process has not been elucidated. Here, we have performed a comprehensive longitudinal analysis of the systemic innate immune cell repertoire during the course of AIT. Patients with allergy received standard preseasonal subcutaneous AIT with allergoids to birch and/or grass. Healthy controls were monitored without any intervention. Flow cytometry of innate lymphoid cell (ILC), natural killer cell, monocyte cell, and dendritic cell (DC) subsets was performed at baseline, 3 months (birch season), 6 months (grass seasons), and 12 months after the therapy in patients or at similar seasonal time points in controls. Additional analyses were performed in the third-year birch and grass season. We observed a durable decrease in group 2 ILCs and an increase of group 1 ILCs after AIT, with dynamic changes in their composition. We found that an expansion of CD127+CD25++ clusters caused observed shifts in the heterogeneity of group 1 ILCs. In addition, we observed development of CD127+CD25++c-Kit+ group 3 ILC clusters. Moreover, we found an increase in the number of intermediate monocytes in parallel with a reduction in nonclassical monocytes during the first year after AIT. Classical and intermediate monocytes presented significant heterogeneity in patients with allergy, but AIT reduced the HLA-DR++ clusters. Finally, an increase in plasmacytoid DCs and CD141+ myeloid DCs was observed in individuals with allergy, whereas the number of CD1c+ myeloid DCs was reduced during the first year of AIT. AIT induces changes in the composition and heterogeneity of circulating innate immune cells and brings them to the level observed in healthy individuals. Monitoring of ILCs, monocytes, and DCs during AIT might serve as a novel biomarker strategy.

Allergome-wide peptide microarrays enable epitope deconvolution in allergen-specific immunotherapy

The interaction of allergens and allergen-specific IgE initiates the allergic cascade after crosslinking of receptors on effector cells. Antibodies of other isotypes may modulate such a reaction. Receptor crosslinking requires binding of antibodies to multiple epitopes on the allergen. Limited information is available on the complexity of the epitope structure of most allergens. We sought to allow description of the complexity of IgE, IgG4, and IgG epitope recognition at a global, allergome-wide level during allergen-specific immunotherapy (AIT). We generated an allergome-wide microarray comprising 731 allergens in the form of more than 172,000 overlapping 16-mer peptides. Allergen recognition by IgE, IgG4, and IgG was examined in serum samples collected from subjects undergoing AIT against pollen allergy. Extensive induction of linear peptide-specific Phl p 1- and Bet v 1-specific humoral immunity was demonstrated in subjects undergoing a 3-year-long AIT against grass and birch pollen allergy, respectively. Epitope profiles differed between subjects but were largely established already after 1 year of AIT, suggesting that dominant allergen-specific antibody clones remained as important contributors to humoral immunity following their initial establishment during the early phase of AIT. Complex, subject-specific patterns of allergen isoform and group cross-reactivities in the repertoires were observed, patterns that may indicate different levels of protection against different allergen sources. The study highlights the complexity and subject-specific nature of allergen epitopes recognized following AIT. We envisage that epitope deconvolution will be an important aspect of future efforts to describe and analyze the outcomes of AIT in a personalized manner.

Der p 1-specific regulatory T-cell response during house dust mite allergen immunotherapy.

Allergen-specific immunotherapy (AIT) is the only available treatment for allergic diseases that can induce specific immune tolerance to allergens. The key mechanisms involved in this process include changes in allergen-specific regulatory T (Treg) cells. We studied 25 allergic rhinitis patients undergoing subcutaneous house dust mite-specific immunotherapy. Peripheral blood mononuclear cells were studied before and after 10, 30weeks, and 3years of AIT. Der p 1-specific T regulatory cell responses were investigated by characterization of Der p 1-MHC class II tetramer-positive cells and correlated with nasal symptom score. Twelve of 25 AIT patients matched with their MHC class II expression to the Der p 1 peptide-MHC class II tetramers. A significant increase in the numbers of Der p 1-specific FOXP3+ Helios+ CD25+ CD127- Treg cells after 30weeks was observed, which slightly decreased after 3years of AIT. In contrast, Der p 1-specific immunoglobulin-like transcript 3 (ILT3)+ CD25+ Treg cells decreased substantially from baseline after 3years of AIT. ILT3+ Treg cells displayed compromised suppressive function and low FOXP3 expression. In addition, Der p 1-specific IL-10 and IL-22 responses have increased after 30weeks, but only IL-10+ Der p 1-specific Treg cells remained present at high frequency after 3years of AIT. Increased number of FOXP3+ Helios+ and IL-10+ and decreased ILT3+ Treg cell responses correlated with improved allergic symptoms. The results indicate that AIT involves upregulation of the activated allergen-specific Treg cells and downregulation of dysfunctional allergen-specific Treg cell subset. Correction of dysregulated Treg cells responses during AIT is associated with improved clinical response.

Factors Associated with Adherence to Allergen Specific Subcutaneous Immunotherapy

PurposeAllergen-specific immunotherapy (AIT) is known to be the only therapeutic modality to alter the natural course of allergic diseases. However, at least 3 years of treatment is recommended for achieving long-term disease modifying effect. This study aimed to investigate factors associated with immunotherapy non-adherence in real practice.Materials and MethodsWe retrospectively reviewed medical records of patients who were diagnosed with allergic rhinitis, asthma, or atopic dermatitis, and received AIT to common allergens such as house dust mite and/or pollens from January 2007 to August 2014. In this study, non-adherence was defined as not completing 3 years of AIT.ResultsAmong 1162 patients enrolled, 228 (19.6%) failed to complete 3 years of AIT. In multivariate analysis, age less than 20 years [odds ratio (OR) 3.11, 95% confidence interval (CI) 1.70–5.69] and 20 to 40 years (OR 2.01, 95% CI 1.17–3.43), cluster build-up (OR 1.78, 95% CI 1.05–3.02) and ultra-rush build-up schedules (OR 5.46, 95% CI 2.40–12.43), and absence of visit to other departments in the same hospital (OR 1.87, 95% CI 1.05–3.32) were independently associated with immunotherapy non-adherence. Disease duration of 5–10 years was negatively associated with non-adherence compared to shorter disease duration of less than 5 years (OR 0.61, 95% CI 0.40–0.94). Although male sex and commercial product of AIT, Tyrosine S®, compared to Novo-Helisen® were non-adherent factors in univariate analysis, no statistical significances were identified in multivariate analysis.ConclusionVarious factors are associated with immunotherapy adherence affecting the utility of immunotherapy. Clinicians should be aware of factors associated with adherence to maximize the utility of allergen-specific subcutaneous immunotherapy.

Does clinical outcome of birch pollen immunotherapy relate to induction of blocking antibodies preventing IgE from allergen binding? A pilot study monitoring responses during first year of AIT

BackgroundThe clinical benefit of allergen-specific immunotherapy (AIT) involves induction of blocking antibodies. It is not clear if these antibodies function via steric hindrance alone or a combination of levels, avidities, and epitope specificities, and clinical outcome cannot be predicted. We aim to in-depth characterize serum antibody profiles during birch pollen AIT, investigate therapy-induced antibodies for their capacity to block IgE binding to Bet v 1 and correlate data with clinical outcomes.MethodsImmune responses of five birch pollen allergic patients were monitored during the first year of AIT by nasal provocation tests (NPTs), ImmunoCAP, immunoblots, direct and avidity enzyme-linked immunosorbent assays, mediator release assays, facilitated antigen binding (FAB) assays, and inhibition mediator release assays.ResultsThere was no correlation between NPT results and therapy-induced changes in levels (IgE, IgG, IgA, IgM), avidities, or mediator release potency of Bet v 1-specific antibodies. In FAB assays, blocking antibodies initiated upon AIT were shown to prevent formation of Bet v 1-IgE complexes of an indicator serum pool and significantly correlated with clinical readout. Inhibition mediator release assays using patient-specific IgE for passive sensitization revealed therapy-induced blocking capacities with very good correlation to NPT results. Notably, this assay was the only one to detect a non-responder during treatment in this pilot study.ConclusionsClinical outcome of AIT depends on induction of blocking antibodies able to prevent the patient’s own IgE from allergen binding. Monitoring of clinical efficacy seems to be best achieved using the inhibition mediator release assay, as development of relevant blocking antibodies can be verified in a patient-tailored manner.

Long-term effects of allergen-specific subcutaneous immunotherapy for house dust mite induced allergic rhinitis.

Allergic rhinitis is strongly associated with the presence of house dust mites. This study investigated the long-term effects of allergen-specific immunotherapy. Allergen-specific immunotherapy was applied over three years. The study was based on a 10-year follow up of patients with allergic rhinitis. The study was conducted between 2001 and 2015. Skin prick test results and symptom scores were evaluated before (26 patients) and after 3 years (20 patients) of allergen-specific immunotherapy (using data from a previously published study), and 10 years after allergen-specific immunotherapy had ended (20 of 26 patients). The symptom scores before allergen-specific immunotherapy were significantly higher than those obtained after 3 years of allergen-specific immunotherapy and 10 years after allergen-specific immunotherapy (p 0.0175). Subcutaneous immunotherapy is an effective treatment for house dust mite induced allergic rhinitis.

Changes in skin reactivity and associated factors in patients sensitized to house dust mites after 1 year of allergen-specific immunotherapy.

BackgroundAllergen-specific immunotherapy (SIT) can significantly improve symptoms and reduce the need for symptomatic medication.ObjectiveThe aim of this study was to investigate changes in skin reactivity to house dust mites (HDMs) as an immunologic response and associated factors after 1 year of immunotherapy.MethodsA total of 80 patients with allergic airway diseases who received subcutaneous SIT with HDMs from 2009 to 2014 were evaluated. The investigated parameters were basic demographic characteristics, skin reactivity and specific IgE for HDM, serum total IgE level, blood eosinophil counts, and medication score.ResultsThe mean levels of skin reactivity to HDMs, blood eosinophil counts, and medication scores after 1 year were significantly reduced from baseline. In univariate comparison of the changes in skin reactivity to HDMs, age ≤30 years, HDMs only as target of immunotherapy, and high initial skin reactivity (≥2) to HDMs were significantly associated with the reduction in skin test reactivity. In multivariate analysis, high initial skin reactivity and HDMs only as target allergens were significantly associated with changes in skin reactivity to HDMs. In the receiver operating characteristic curve of the initial mean skin reactivity to HDMs for more than 50% reduction, the optimal cutoff value was 2.14.ConclusionThis study showed significant reductions in allergen skin reactivity to HDMs after 1 year of immunotherapy in patients sensitized to HDMs. The extent of initial allergen skin reactivity and only HDMs as target allergen were important predictive factors for changes in skin reactivity.

C-type Lectin Receptor Expression on Human Basophils and Effects of Allergen-Specific Immunotherapy.

Basophils are emerging as immunoregulatory cells capable of interacting with their environment not only via their characteristic IgE-mediated activation, but also in an IgE-independent manner. Basophils are known to express and respond to stimulation via TLR2, TLR4, DC-SIGN and DCIR, but whether basophils also express other C-type lectin receptors (CLRs) is largely unknown. In this study, we investigate the CLR expression profile of human basophils using multicolour flow cytometry. As FcRs as well as some CLRs are associated with allergen recognition and shown to be involved in subsequent immune responses, the expression of CLRs and FcRs on peripheral blood basophils, as well as their frequency, was monitored for 1year in subjects undergoing subcutaneous allergen-specific immunotherapy (AIT). Here, we show that human basophils express CLECSF14, DEC205, Dectin-1, Dectin-2 and MRC2. Furthermore, we demonstrate that the frequencies of basophils expressing the allergy-associated CLRs Dectin-1 and Dectin-2 were significantly reduced after 1year and 8weeks of AIT, respectively. In contrast, the frequency of basophils positive for FcγRII, as well as the fraction of total basophils, significantly increased after 1year of AIT. The herein demonstrated expression of various CLRs on basophils, and their altered CLR and FcR expression profile upon AIT, suggest yet unexplored ways by which basophils can interact with antigens and may point to novel immunoregulatory functions targeted through AIT.

Allergen-Specific Immunotherapy Alters the Frequency, as well as the FcR and CLR Expression Profiles of Human Dendritic Cell Subsets.

Allergen-specific immunotherapy (AIT) induces tolerance and shifts the Th2 response towards a regulatory T-cell profile. The underlying mechanisms are not fully understood, but dendritic cells (DC) play a vital role as key regulators of T-cell responses. DCs interact with allergens via Fc receptors (FcRs) and via certain C-type lectin receptors (CLRs), including CD209/DC-SIGN, CD206/MR and Dectin-2/CLEC6A. In this study, the effect of AIT on the frequencies as well as the FcR and CLR expression profiles of human DC subsets was assessed. PBMC was isolated from peripheral blood from seven allergic donors before and after 8 weeks and 1 year of subcutaneous AIT, as well as from six non-allergic individuals. Cells were stained with antibodies against DC subset-specific markers and a panel of FcRs and CLRs and analyzed by flow cytometry. After 1 year of AIT, the frequency of CD123+ DCs was increased and a larger proportion expressed FcεRI. Furthermore, the expression of CD206 and Dectin-2 was reduced on CD141+ DCs after 1 year of treatment and CD206 as well as Dectin-1 was additionally down regulated in CD1c+ DCs. Interestingly, levels of DNGR1/CLEC9A on CD141+ DCs were increased by AIT, reaching levels similar to cells isolated from non-allergic controls. The modifications in phenotype and occurrence of specific DC subsets observed during AIT suggest an altered capacity of DC subsets to interact with allergens, which can be part of the mechanisms by which AIT induces allergen tolerance.

FoxP3 Tregs Response to Sublingual Allergen Specific Immunotherapy in Children Depends on the Manifestation of Allergy.

Over the last decades allergic diseases has become a major health problem worldwide. The only specific treatment to date is allergen specific immunotherapy (ASIT). Although it was shown that ASIT generates allergen-tolerant T cells, detailed mechanism underlying its activity is still unclear and there is no reliable method to monitor its effectiveness. The aim of our study was to evaluate ASIT influence on the frequency of forkhead box P3 (FoxP3) Tregs in allergic children with various clinical manifestations. The relative number of FoxP3 Tregs in 32 blood samples from allergic children at baseline and/or after 1 year of ASIT was assessed by flow cytometry. In the entire studied group, the percentage of FoxP3 Tregs did not increase 1 year after ASIT. Nevertheless, the percentage of FoxP3 Tregs after ASIT significantly increased in children with respiratory allergy (conjunctivitis, asthma, and rhinitis) coexisting with nonrespiratory manifestations (food allergy and/or atopic dermatitis), whereas, in patients with respiratory allergy only, the percentage of FoxP3 Tregs decreased. To the best of our knowledge, this is the first report showing various differential FoxP3 Tregs response to ASIT in allergic children. FoxP3 Tregs number could be useful in treatment monitoring. Further studies are warranted to confirm these observations.

Immunological changes after ASIT in AD allergen-specific immunotherapy and their potential correlation with clinical response in patients with atopic dermatitis patients sensitized to house dust mite.

Allergen-specific immunotherapy (ASIT) is the main treatment for inducing long-term immunological and clinical tolerance in patients with IgE-mediated allergic diseases. Recent open-label and controlled studies on the efficacy of ASIT in patients with atopic dermatitis (AD) have provided promising results. However, data about possible relationship between the improvement of clinical symptoms and changes of serum cytokines are limited. Seventy-nine patients with moderate to severe AD sensitized to house dust mite (HDM) were enrolled. Fifty-eight patients were treated with ASIT and 11 controls received only symptomatic treatment. The disease activity in AD patients was evaluated by using the patient-oriented eczema measure (POEM) system. Serum interleukin (IL)-4, IL-10, interferon (IFN)-γ, transforming growth factor (TGF) β1, total IgE, HDM-specific IgE (s-IgE) and HDM-specific IgG4 (s-IgG4) were measured before and after 2years of therapy. The mean patient-oriented eczema measure system (POEM) score of AD patients with ASIT significantly decreased after 2years of treatment, compared to that in patients without ASIT. After ASIT, the serum levels of IL-10, TGF-β1, IFN-γ and s-IgG4 increased, while the level of IL-4 decreased. The change in the POEM score was negatively correlated with changes of serum concentration of TGF-β1, s-IgG4 and IFN-γ. Furthermore, s-IgG4 levels were positively correlated with changes in the IL-10 levels. No correlation between POEM score and serum IL-10 or IL-4 was observed. Clinical symptoms and the quality of life of AD with HDM sensitization could be improved after 2years of ASIT. Changes in serum IL-10, TGF-β1, s-IgG4 and IFN-γ might be considered as biomarkers to assist clinical evaluation of the therapeutic effects of ASIT in patients with AD.

Upregulated levels of human β‐defensins in patients with seasonal allergic rhinitis after allergen‐specific immunotherapy treatment

Antimicrobial peptides (AMPs) are important actors in the innate immune system. One class of AMPs is the human β-defensins (HBDs), a group of small peptides with a broad spectrum of antimicrobial activities. Expression of HBDs is downregulated in different manifestations of allergic disease. In this study, we examine whether allergen-specific immunotherapy (ASIT) affects the nasal levels of HBDs in patients with seasonal allergic rhinitis (SAR). Nasal biopsies were examined for the occurrence of HBD1-3 with real-time reverse-transcription polymerase chain reaction (RT-PCR) and immunohistochemistry. Nasal lavage (NAL) fluids from healthy individuals, untreated SAR patients and SAR patients before and after ASIT were analyzed for levels of HBD1-3 using enzyme-linked immunosorbent assay (ELISA). Examination of nasal biopsies revealed HBD1-3 expression at gene level as well as at protein level in all samples tested. HBD1 and HBD3 messenger RNA (mRNA) levels were downregulated in SAR patients compared to healthy individuals. All HBDs were found in NAL fluids. SAR patients having completed 3 years of ASIT displayed higher levels of HBD1 and HBD2 than before treatment, whereas levels of HBD3 were unaffected. The present study demonstrates an upregulation of HBD1 and HBD2 in SAR patients after completion of ASIT. This may reflect the importance of an intact innate immune response as part of our defense against infections among allergic individuals.

Immunological mechanisms of sublingual allergen-specific immunotherapy

Within the last 100 years of allergen-specific immunotherapy, many clinical and scientific efforts have been made to establish alternative noninvasive allergen application strategies. Thus, intra-oral allergen delivery to the sublingual mucosa has been proven to be safe and effective. As a consequence, to date, sublingual immunotherapy (SLIT) is widely accepted by most allergists as an alternative to conventional subcutaneous immunotherapy. Although immunological mechanisms remain to be elucidated in detail, several studies in mice and humans within recent years provided deeper insights into local as well as systemic immunological features in response to SLIT. First of all, it was shown that the target organ, the oral mucosa, harbours a sophisticated immunological network as an important prerequisite for SLIT, which contains among other cells, local antigen-presenting cells (APC), such as dendritic cells (DCs), with a constitutive disposition to enforce tolerogenic mechanisms. Further on, basic research on local DCs within the oral mucosa gave rise to possible alternative strategies to deliver the allergens to other mucosal regions than sublingual tissue, such as the vestibulum oris. Moreover, characterization of oral DCs led to the identification of target structures for both allergens as well as adjuvants, which could be applied during SLIT. Altogether, SLIT came a long way since its very beginning in the last century and some, but not all questions about SLIT could be answered so far. However, recent research efforts as well as clinical approaches paved the way for another exciting 100 years of SLIT.

Evaluation of serum s-IgE/total IgE ratio in predicting clinical response to allergen-specific immunotherapy

To date, no predictive tests for the clinical response to allergen-specific immunotherapy (ASI) are available. Therefore an in vivo or in vitro test would be of great value. We sought to evaluate pretreatment parameters used in diagnosing allergic rhinitis and determining serum specific IgE (s-IgE) levels, serum total IgE (t-IgE) levels, and blood eosinophil counts and to identify whether can be used to predict clinical improvement in monosensitized patients with allergic rhinitis with or without asthma treated with immunotherapy. We analyzed 279 patients who had undergone 4 years of ASI administered either by means of the subcutaneous immunotherapy (76 patients) or sublingual immunotherapy (203 patients) routes. Serum t-IgE and s-IgE levels, blood eosinophil counts, and serum s-IgE/t-IgE ratios were calculated and tested for correlation with clinical response to ASI. Receiver operating characteristic curves were determined. Predicted probabilities and predictive areas under the curve were calculated. The clinical response to ASI was effective in 145 (52.0%) of 279 total patients, 42 (55.2%) of 76 patients treated with subcutaneous immunotherapy, and 103 (50.7%) of 203 patients treated with sublingual immunotherapy. A significant correlation was found between the serum s-IgE/t-IgE ratio and the clinical response to ASI, with high ratios (>16.2) associated with an effective response. The sensitivity and specificity of the area under the curve of the ratio were higher than those of serum s-IgE and t-IgE alone. The calculation of the serum s-IgE/t-IgE ratio for predicting the clinical response to ASI offers an advantage over measuring t-IgE and s-IgE levels in monosensitized patients for the following allergens: grass, Parietaria judaica, Olea europea, and house dust mite.

Reduction of Substance P in Nasal Lavage Fluid after Allergen Challenge of Mugwort Allergic Patients during Allergen Immunotherapy

Allergen specific immunotherapy (ASIT) may impact neuropeptides released into nasal lavage fluid (NLF) including substance P (SP). 15 subjects (8 females and 7 males) mean age 33.0 ± 7.8 years with symptoms during the previous mugwort pollen season were treated with ASIT as pre-seasonal weekly injections of a mugwort pollen allergoid (Allergovit) for 3 years. All had both positive skin prick tests to mugwort pollen allergen and elevated specific IgE to mugwort pollen (Phadia). The control group consisted of 9 untreated subjects. Nasal mugwort allergen challenge with subsequent lavage performed 15 minutes post-challenge was done by the method of Naclerio. The concentration of SP in NLF was determined by RIA (Incstar, USA). Nasal symptoms during the pollen seasons were recorded. Reduction of symptom scores occurred during the three years of ASIT. Levels of SP in NLF after nasal mugwort challenge in both groups prior to therapy were similar: ASIT group - SP 55.1 ± 15.5 pg/ml versus control group- 54.3 ± 10.1 pg/ml. SP levels in NLF 15 minutes after mugwort allergen challenge were significantly less after 1 year of ASIT versus controls (47.4 ± 14.0 pg/ml versus 53.6 ± 6.8 pg/l) with modest further decrease in SP levels in post-challenge NLF after 2 years of ASIT (42.2 ± 9.6 pg/ml versus 51.2 ± 9.2 pg/ml) and 3 years of ASIT (41.6 ± 18.3 pg/ml versus 51.8 ± 7.6 pg/ml). SP may play a role in nasal allergic responses to mugwort pollen. Decreased release of SP upon nasal allergen challenge occurs with each year of ASIT suggesting that ASIT reduces allergen-induced SP release.