Ragweed Sensitivity Research Articles

Frequency of ragweed sensitization and allergy among patients with respiratory allergy

Pollen is well known to cause seasonal allergy. Ragweed sensitization and allergy represent a worldwide challenge for allergists. Ambrosia is one of the major genera in the Asteraceae family which includes at least 51 species known as "ragweed". The current study aimed at determining frequency of ragweed sensitization and allergy among patients with respiratory allergy. The study included 220 subjects selected from patients attended the Allergy Clinic, Ain Shams University. All patients were subjected to detailed medical history, clinical examination, asthma severity grading according to the Global Initiative for Asthma (GINA) guidelines, allergic rhinitis severity grading according to the allergic rhinitis and its impact on asthma (ARIA) guidelines, pulmonary function tests for asthmatic patients, complete blood count with differential for detection of eosinophilia, serum total IgE and skin prick testing (SPT) to ragweed pollen together with common inhalants and common food allergens. Specific IgE for Ambrosia artemisiifolia was done for patients who showed positive SPT to ragweed pollen. About 34% of patients had positive SPT to ragweed, 30.5% were sensitized to ragweed and 3.2% allergic. Specific IgE for A. artemisiifolia was positive in 33.8%. There was a statistically significant association between ragweed sensitization and level of asthma control and disease duration. We concluded that ragweed sensitization is less common as the frequency of Ambrosia pollen sensitization was about one third of the studied allergic patients.

Trained immunity induced by in vivo peptide-based STAT6 inhibition prevents ragweed allergy in mice

BackgroundTrained immunity is the ability of the innate immune system to form immune memory responses to provide support the formation of appropriate adaptive responses. Allergic airways disease (AAD) is a maladapted immune response to allergens, initiated and maintained by the type 2 (T2) inflammatory pathway. It is predicated by the elaboration of cytokines IL-4 and IL-13 and follows activation of the STAT6 transcription factor.ObjectiveTo investigate the role of trained immunity in mucosal immune responses following neonatal vaccination with the STAT6 inhibitory peptide (STAT6-IP), in preventing the development of ragweed-induced AAD.MethodsWe demonstrate that transfer of CD4+ T cells or dendritic cells (DC) from STAT6-IP vaccinated wild-type BALB/c mice to naïve mice, that were subsequently chronically exposed to sensitizing doses of ragweed allergen, is sufficient to prevent development of T2 responses in recipients.ResultsOur results demonstrate significant reductions in; airways hyperresponsiveness (AHR); ragweed-specific IgE; pulmonary inflammation; T2 cytokines; and inflammatory gene expressions in recipient mice. Expression of IDO, TGFβ and T regulatory cells were all significantly increased. Anti-TGFβ treatment during the ragweed sensitization phase re-constituted the pro-inflammatory T2 immune response. We show that tolerance can be attained via DC trained in the STAT6-IP-mediated tolerant milieu. This effect is not restricted to a particular allergen and does not require antigen-mediated T cell activation prior to transfer.ConclusionAdoptive transfer experiments suggest that STAT6-IP treatment trains dendritic and cells to mediate tolerant immunity to chronic ragweed exposure in the airways. This indicates that early transient STAT6-inhibition constitutes an effective immunomodulatory airways allergy preventative strategy.

Your Grandchildren's Pollen? Modeling the Future of Ragweed Sensitization in Europe.

Your Grandchildren's Pollen? Modeling the Future of Ragweed Sensitization in Europe.

Heterogeneity in ragweed pollen exposure is determined by plant composition at small spatial scales

Pollen allergies are one of the most common health problems in the United States and over 20% of Americans are sensitized to the pollen produced by common ragweed (Ambrosia artemisiifolia L.). Despite the importance of allergenic pollen to public health, no research has linked land use and plant populations to spatial heterogeneity in airborne pollen concentrations. In order to quantify these relationships and elucidate the processes which lead to pollen exposure, we surveyed ragweed stem density in Detroit (Michigan, USA) as a function of land use. We then deployed 34 pollen collectors throughout the city and recorded ragweed cover in the immediate vicinity of each pollen collector. We found that ragweed populations were highest in vacant lots, a common land cover type in Detroit. Because ragweed population density was so strongly correlated to vacant lots, for which spatially explicit data were available, we were able to investigate whether observed ragweed pollen concentrations were a function of land use at the spatial scales of 10m and 1km. Both relationships were significant, and the combination of these two variables predicts a large portion of airborne ragweed pollen concentrations (R2=0.48). These results emphasize the important role of pollen production within the urban environment and show that management of allergenic pollen producing plants must be considered at multiple spatial scales. Our findings also demonstrate that there is too much spatial heterogeneity for a pollen collector at any given site to portray the allergenic pollen load experienced by different individuals within the same city. Finally, we discuss how spatial correlations between socio-economic status, vacant lots, and ragweed could help to explain the disproportionate amount of allergies and ragweed sensitization experienced by low income and minority populations in Detroit.

O13 ‐ Regional differences in sensitisation to ragweed in Croatian children are not associated solely with pollen concentration

FP7 project ATOPICA (Atopic diseases in changing climate, land use and air quality) supported by EU Grant agreement NO: CP 282687 explores the combined pan-European impact of changes in climate, land use and air pollution on allergen pollen-induced diseases with an accent on atopy due to ragweed sensitization. Sensitization to ragweed pollen correlates with levels of airborne pollen concentration in environment, but can be enhanced by other environmental factors such as air pollution.

Sensitization to Common Ragweed in Southern Bavaria: Clinical and Geographical Risk Factors in Atopic Patients

Background: Sensitization to common ragweed (Ambrosia artemisiifolia) is associated with a variety of risk factors, which are incompletely defined. Our aim was to evaluate the association of a variety of clinical, geographical and demographical variables with ragweed sensitization and also to determine its frequency in southern Bavaria. Methods: In this cross-sectional multicentre study, we enrolled 977 patients with a documented or suspected atopic disease or food allergy. Data were collected on aeroallergen sensitization, age, sex, type and history of allergic disease, place of residence and potential local ragweed exposure. For this last variable, county ragweed cover was taken as a surrogate variable. Relative rates were calculated with multiple additive logistic regression models. Randomly selected patients with ragweed sensitization had a conjunctival provocation test. Results: According to skin prick tests, 190 patients (19.5%) were sensitized to ragweed. The frequency of this finding increased significantly with a rising number of additional sensitizations. Other less important predictors for a ragweed sensitization were male gender, mugwort sensitization, food allergy and a maximum of complaints in September or October. County of residence, extent of local ragweed cover or type of residential area were without relevance. Of 48 sensitized patients, 26 (54.2%) had a positive conjunctival provocation test. Discussion: Patients with multiple sensitizations may be more readily sensitized to a new aeroallergen. Local geographic or environmental conditions are presumably of minor importance for becoming sensitized to ragweed. The frequency of ragweed allergy among sensitized patients might be high.

IgE Reactivity Patterns in Patients with Allergic Rhinoconjunctivitis to Ragweed and Mugwort Pollens

Differential diagnosis between ragweed and mugwort pollen allergy represents a large clinical problem in areas where both plants are present. The aim of this study was to investigate ragweed- and mugwort-sensitized patients to identify specific IgE reactivity profiles. Results were correlated to clinical findings such as medical history and health-related quality of life (HRQL). Seventy-four patients with allergic rhinoconjunctivitis between July and October were examined and underwent in vivo tests (skin-prick test [SPT] and nasal provocation). Sera were evaluated for IgE reactivity to mugwort and ragweed pollen extracts, major (Art v 1; Amb a 1) and minor (profilin and calcium-binding protein) allergens. HRQL was evaluated using a standardized questionnaire. Seventy-one patients revealed positive SPT reactivity against mugwort and 60 patients against ragweed extracts. Of these patients, 74 revealed IgE antibodies against mugwort extracts, whereas anti-Art v 1 antibodies were detectable in 50 individuals. Fifty-five patients showed IgE antibodies against natural ragweed extracts; anti-Amb v 1 antibodies were detected in six cases only. Using standardized clinical history and HRQL questionnaires we were not able to detect any differences within different reactivity patterns. Within the investigated population of 74 weed-allergic patients the prevalence of true mugwort and ragweed sensitization can be calculated as 68 and 8%. High prevalence of ragweed sensitization when testing with full extracts can be explained by cross-reactivity between other weeds, e.g., mugwort rather than cosensitization. Differences in medical history and HRQL between different reactivity patterns were not detectable.

Sensitization rates of airborne pollen and mold in children

PurposeAeroallergens are important causative factors of allergic diseases. Previous studies on aeroallergen sensitization rates investigated patients groups that had visited pediatric allergy clinics. In contrast, we investigated sensitization rates in a general population group of elementary school to teenage students in Incheon, Jeju, and Ulsan.MethodsAfter obtaining parental consent, skin-prick tests were performed on 5,094 students between March and June 2010. Elementary school students were tested for 18 common aeroallergens, whereas middle and high school students were tested for 25 allergens. The 25 allergens included Dermatophagoides pteronyssinus, Dermatophagoides farinae, pollen (birch, alder, oak, Japanese cedar, pine, willow, elm, maple, Bermuda grass, timothy grass, rye grass, orchard grass, meadow grass, vernal grass, mugwort, Japanese hop, fat hen, ragweed, and plantain), and mold (Penicillatum, Aspergillus, Cladosporium, and Alternaria).ResultsThe sensitization rates in descending order were 25.79% (D. pteronyssinus), 18.66% (D. farinae), 6.20% (mugwort), and 4.07% (willow) in Incheon; 33.35% (D. pteronyssinus), 24.78% (D. farinae), 15.36% (Japanese cedar), and 7.33% (Alternaria) in Jeju; and 32.79% (D. pteronyssinus), 30.27% (D. farinae), 10.13% (alder), and 8.68% (birch) in Ulsan. The dust mite allergen showed the highest sensitization rate among the 3 regions. The sensitization rate of tree pollen was the highest in Ulsan, whereas that of Alternaria was the highest in Jeju. The ragweed sensitization rates were 0.99% in Incheon, 1.07% in Jeju, and 0.81% in Ulsan.ConclusionThe differences in sensitization rates were because of different regional environmental conditions and distinct surrounding biological species. Hence, subsequent nationwide studies are required.

Evolution of ragweed pollen concentrations, sensitization and related allergic clinical symptoms in Parma (northern Italy)

The pollen released in the atmosphere by the ragweed represents a question of public health in several European countries. In Italy, the ragweed is mostly distributed in the North. In our region (Emilia Romagna), the presence of ragweed was not described yet if not occasionally, but this plant is thriving well in the North of the Po river. The aim of our study was to estimate the concentration trends of ragweed pollens in the air of Parma starting from 1992 until 2008 and to describe the clinical related situation. The aerobiological surveillance was made with the methods standardized by the Italian Association of Aerobiology. We analyzed 19,468 outpatients affected by respiratory disease. The patients studied address our clinical Center, mainly with pathologies respiratory, most of them with allergic origin. To detect the existence of significant trends and correlations since, we used the non-parametric tests with SPSS software. Our observations showed that since 1995, the year until when pollens of ragweed were only sporadically observed in the air of Parma, there has been a significant increase in ragweed pollens. Among the patients addressed at our clinical Center, 876 patients had positive SPT (skin prick test) for ragweed pollen with respiratory illnesses, all polysensitized. Besides, we found a significant increase in patients with positive SPT for the ragweed, and among these, the increase in the asthma has been significant. On the basis of our results, we expect, in the absence of intervention from public authorities, a more significant increase in the positive subjects and an aggravation of the symptoms related to the presence of ragweed pollen in the air of Parma.

Immunologic Effects of Sublingual Immunotherapy: Clinical Efficacy Is Associated With Modulation of Programmed Cell Death Ligand 1, IL-10, and IgG4

S Piconi, D Trabattoni, V Rainone. J Immunol. 2010;185(12):7723–7730 To evaluate an optimal treatment regimen for sublingual immunotherapy (SLIT) and investigate the underlying mechanism. There were 62 Italian patients aged 19 to 60 years enrolled from a clinic in Milano, Italy, between February and September 2009. Inclusion criteria were a clinical history that suggested ragweed sensitization, a positive skin-prick-test result to ragweed pollen, and a clinical report of asthma and/or rhinoconjunctivitis. The patients were randomly assigned to 1 of 4 treatment arms: preseasonal SLIT (5 months); seasonal SLIT (3 months); prolonged SLIT (5 …

Immunological Effects of Sublingual Immunotherapy: Clinical Efficacy Is Associated with Modulation of Programmed Cell Death Ligand 1, IL-10, and IgG4

Sublingual immunotherapy (SLIT) is an alternate route of administration of allergen-specific immunotherapy with an improved safety profile; to clarify the immune mechanisms elicited by this therapy, we analyzed the clinical and immunologic effects of SLIT in patients with a clinical history of ragweed sensitization. To analyze possible difference among immunotherapeutic protocols, we also compared patients receiving preseasonal, seasonal, or prolonged sublingual therapy (≥ 3 y); patients receiving symptomatic therapy alone were enrolled as well in the study. Clinical and immunological parameters were measured twice in and out of the pollination period. Clinical benefits, as measured by the visual analog scale for symptoms and for use of drugs, were evident in all three groups of individuals receiving immunotherapy, but were significantly better in patients undergoing prolonged SLIT. Immunologically, SLIT resulted in increased IL-10 production, programmed cell death ligand 1 expression, and concentration of allergen-specific IgG4, as well as in the reduction of CD80 and CD86 expression and IL-4 production. SLIT, thus, is associated with modulation of programmed cell death ligand 1 expression and IL-10 synthesis and favors the production of allergen-specific IgG4. These effects are evident from the first pollen season, independently from therapeutic regimen (preseasonal or seasonal) even if a prolonged treatment is necessary to obtain full clinical efficacy. A more detailed understanding of the interaction of allergen and APCs within the oral mucosa will allow improved targeting of allergy vaccine.

Post-Katrina Changes in Ragweed Pollen Concentrations and Sensitivity Levels

Post-Katrina Changes in Ragweed Pollen Concentrations and Sensitivity Levels

Phosphodiesterase IV and neutral endopeptidase in airways from developing and allergen sensitized rabbits

Phosphodiesterase IV (PDE IV) and neutral endopeptidase (NEP) may modulate the neurally mediated nonadrenergic noncholinergic inhibitory (NANCi) response. This response is not present in normal rabbits until 2 weeks of age. Allergen sensitization and challenge of fully grown 13-week old rabbits decreases the NANCi response. Our goal was to assess NANCi as a function of age and allergen sensitization. Tracheal smooth muscle (TSM) rings from normal 1-, 2-, and 13-week old rabbits plus ragweed immune as well as ragweed immune/challenged (I/C) 13-week old rabbits were assessed. Colorimetric assays of PDE IV and NEP activity were conducted on TSM from each group. NANCi responses were obtained in the presence and absence of Ro 20-1724 (PDE IV inhibitor) and/or phosphoramidon (Phos; NEP inhibitor) after contraction of TSM with neurokinin A. In normal TSM, there was no difference in PDE IV as a function of age. Conversely, NEP decreased significantly from 1 to 13 weeks of age. The immune and I/C groups had decreases in NEP and increases in PDE IV that were significant. Neither Ro 20-1724 nor Phos alone or together increased NANCi responses in TSM from 1- or 2-week old rabbits. However, both enhanced relaxation in TSM from normal, immune, and I/C 13-week old rabbits with an additive effect when drugs were combined. This work demonstrates (1) normal maturational changes in NEP but not PDE IV within TSM of this species; (2) modulation of the NANCi response by inhibitors of PDE IV and NEP in 13- but not 2-week old rabbits; (3) increased PDE IV and decreased NEP levels in the immune and I/C groups with reconstitution of NANCi responses by the combination of inhibitors. We conclude that mediation of the NANCi response is different in normal 2- and 13-week old rabbits. Both PDE IV and NEP modulated relaxation in fully grown rabbits, but had no effect at the younger age. Furthermore, both ragweed sensitization alone and ragweed challenge of immune rabbits altered NANCi via increases in PDE IV and decreases in NEP.

Differential Modulation of Allergic Eye Disease by Chronic and AcuteAscarisInfection

To assess alterations in allergic ocular responses to nonparasite antigens in an experimental system in which mice were skewed toward a Th2 cytokine profile by helminth infection. Mice were inoculated with Ascaris suum (A. suum) eggs concurrent with ragweed (RW) sensitization (RW/acute) or by repeated inoculation before RW sensitization (RW/chronic). Control subjects were divided into RW, A. suum, and sham-sensitized groups. Animals were RW-challenged in the eye and examined for changes in ocular responses, inflammatory cell infiltrates, and in vitro assessment of cytokines after antigen restimulation. In subsequent experiments, CD4(+)/CD25+ T regulatory and CD4(+)/CD25- control T cells were adoptively transferred into mice before ocular challenge. RW sensitization and challenge increased ocular symptoms and eosinophil infiltration into the conjunctiva over PBS control eyes. Acute A. suum infection significantly increased RW-induced clinical symptoms and eosinophil infiltrates in the conjunctiva (P = 0.0001) and resulted in the development of anterior uveitis. In contrast, RW/chronic infection provided protection from allergic responses to RW with significantly fewer eosinophils in the eye and reduced eotaxin levels. Transfer of CD4(+)/CD25+ T cells from RW/chronic mice into RW/acute animals also decreased disease intensity, suggesting that T regulatory cells may contribute to protection from allergic eye disease. The current studies suggest acute parasitic infections exacerbate allergic symptoms, whereas chronic infections offer protection and provide possible explanations for the role of parasitic infection in susceptibility and resistance to nonparasite allergens.

Fluticasone Nasal Spray and the Combination of Loratadine and Montelukast in Seasonal Allergic Rhinitis

To compare the effectiveness of an intranasal steroid treatment with that of the combination of a histamine1 receptor antagonist and a leukotriene D receptor antagonist in the treatment of seasonal allergic rhinitis. A 2-week, parallel, randomized, double-blind, double-dummy study with rolling enrollment. Tertiary care medical center. Subjects A total of 63 adults with a 2-year history of ragweed sensitivity in the Chicago, Ill, area and a positive skin-prick reaction to ragweed pollen. Intervention Subjects were randomized to receive either 100 micro g of fluticasone propionate aqueous nasal spray in each nostril or 10 mg of loratadine and 10 mg of montelukast sodium by mouth once daily in the evening for 2 weeks. At visits 1 and 2, subjects completed a quality-of-life questionnaire and underwent nasal lavage to determine total eosinophil count and eosinophil cationic protein (ECP) measurements. Daily symptom diaries were kept for 2 weeks. Questionnaire answers, daily nasal symptom scores, eosinophil counts, and ECP levels. Median total nasal symptom scores were lower in the fluticasone group (4.5 vs 6), but the difference was not statistically significant. The questionnaire answers showed dramatic improvement in overall and individual domains for both groups (P<.01 vs visit 1) with significantly greater reduction in nasal symptoms in the fluticasone group (P<.05). Eosinophil counts and ECP levels were significantly reduced in the fluticasone group. Both treatments provided clinically meaningful responses, but the overall results favored fluticasone propionate.

Allergen Sensitivity and Asthma Severity at an Inner City Asthma Center

The objective of this study was to examine the relationship of allergen sensitivity to asthma symptoms among inner-city asthmatics seen at our Brooklyn, NY, asthma center. We hypothesized that asthma severity would increase for adults and children with increased cockroach and dust mite allergen sensitivity. Data were gathered from retrospective chart review for all patients who were treated at the center with a diagnosis of asthma and had undergone skin-prick testing (SPT) for allergen sensitivity during 1998 (pediatric, n = 79; adult, n = 29). Asthma severity (determined by National Heart, Lung and Blood Institute [NHLBI] asthma severity class) was examined in relation to allergen sensitivity. Allergen sensitivity was measured by percent positive to skin-prick testing as well as by relative mean diameter of skin prick test wheals. For adults, mite sensitivity prevalence was 61% and cockroach sensitivity prevalence was 41%. For children, mite sensitivity prevalence was 49%; cockroach sensitivity prevalence was 42%. For adults, asthma severity correlated significantly with sensitivity to Cladosporium, tree, and grass as measured by percent positive skin tests and by increasing mean diameter of skin test wheals. There was a significant correlation with severity for adult dust mite sensitivity only as measured by increasing mean wheal diameter. Ragweed sensitivity showed a significant correlation with severity only as measured by percent positive skin tests. There was a significant positive association for adults between increasing asthma severity and total number of allergen sensitivities per subject. There was no significant correlation for children between asthma severity and total number of allergen sensitivities per subject. Among children, no specific allergen sensitization showed a significant positive association with asthma severity. By both measures of allergen sensitization, there was a significant negative association for children between Cladosporium and asthma severity. Among our inner-city asthmatic population significant correlation between mite sensitivity and asthma severity was found only in adults. No significant association was seen with cockroach. However, outdoor allergen sensitivity (Cladosporidium, tree, ragweed, and grass) significantly correlated with asthma for adults in this inner city population.

Systemic or mucosal administration of immunostimulatory DNA inhibits early and late phases of murine allergic conjunctivitis.

Seasonal allergic conjunctivitis is one of the most common manifestations of allergic disease, affecting 15 % population in the United States annually. Short ragweed (RW) is a major cause of seasonal allergies. Immunostimulatory DNA sequences (ISS or CpG motifs) can inhibit an on-going Th2/allergic response and induce a de novo Th1 response. In this study, we investigated the ability of these ISS to modulate allergic responses in a RW-induced mouse model of seasonal allergic conjunctivitis. Systemic or mucosal administration of ISS oligonucleotide (ISS-ODN) after RW sensitization inhibited both the immediate hypersensitivity response and the late-phase cellular infiltration and induced a RW-specific Th1 response. ISS-ODN administration suppressed the rise of RW-specific IgE titers after repeated allergen challenge. Furthermore, ISS administration was more effective than dexamethasone in inhibiting the allergic response. Mechanistically, the ISS-induced immunomodulatory effects were abolished when mice were treated with anti-IL-12 neutralizing antibodies, suggesting a pivotal role for type 1 cytokines in the inhibition of both the immediate hypersensitivity and the late-phase cellular infiltration. Thus, ISS-ODN is a novel anti-inflammatory and immunomodulatory agent that significantly inhibits the allergic response and may provide an alternative to the current standard care of ocular allergy.

Do genetics play a role in the pathogenesis of asthma?

Asthma is a phenotypically heterogeneous disorder associated with intermittent respiratory symptoms, bronchial hyperresponsiveness (BHR), and reversible airflow obstruction. 1, 2 Most individuals with asthma have evidence of BHR and atopy, with elevated total serum IgE, allergen-specific IgE, or skin-test reactivity to common allergens. At present, it is not clear whether asthma, BHR, and atopy are clinical manifestations of the same underlying primary defect or whether they share common pathways with distinct primary molecular origins. A genetic component to asthma has long been suggested by studies demonstrating increased prevalences of asthma among first-degree relatives of asthmatic subjects and greater concordance rates among monozygotic compared with dizygotic twins. 3-7 Such “clustering” in families is consistent with a genetic cause but may also reflect the effects of shared environmental exposures. Thus familial clustering does not prove a genetic cause. Although segregation analyses in populations of asthmatic families have suggested the likelihood of a major

Specific V beta T cell subsets mediate the immediate hypersensitivity response to ragweed allergen.

T and B cell responses after sensitization to ragweed (RW) were examined in a mouse model in which BALB/c mice were exposed to the allergen by ultrasonic nebulization. Sensitization resulted in the stimulation of an IgE anti-RW response and was paralleled by a rise in IgG1 anti-RW titers. Skin testing for immediate cutaneous hypersensitivity revealed the presence of allergic type I reactions to RW. Sensitization to RW in this way was also associated with the development of increased airways responsiveness as determined by electrical field stimulation of preparations of tracheal smooth muscle. Histologic examination of the airways and the lung indicated the presence of a mononuclear cell infiltrate in the mucosa and submucosa of the airways that was accompanied by an enlargement of local draining lymph nodes of the airways and the lung. T cell populations were analyzed for the frequency of V beta-expressing T cells. Such analysis indicated that RW sensitization stimulated the expression of V beta 8.1+, V beta 8.2+, and V beta 13+ T cells in the local lymphoid tissue and of V beta 8.1+, V beta 8.2+, V beta 8.3+, V beta 9+ and V beta 14+ T cells in the spleen. Co-culture of these T cell populations with RW-primed B cells indicated that in the presence of RW, V beta 8.2 T cells stimulated IgE and IgG1 production, whereas the other T cell populations showed a different stimulation profile for Ig isotypes and IgG subclasses. The transfer of V beta 8.2 T cells from sensitized but not from nonsensitized control mice stimulated an allergen-specific IgE and IgG1 response and increased airways responsiveness in naive recipients. These data provide additional support for the pivotal role of specific V beta-expressing T cell subpopulations in the stimulation of IgE/IgG1 production and increased airways responsiveness.

Comparison of the in‐vivo and in‐vitro response to ragweed immunotherapy in children and adults with ragweed‐induced rhinitis

In order to compare results of allergen immunotherapy in paediatric and adult populations, 22 children with a history of ragweed hay fever were matched with an equal number of adults for skin sensitivity to ragweed and all were given a 1-year course of immunotherapy with a partially purified ragweed extract. Biological responses were measured by nasal challenges with ragweed before therapy was started, after 12 weekly injections and when the maintenance dose had been reached and also by methacholine bronchoprovocation tests before and after 12 months of therapy. Skin-test sensitivity to ragweed and control allergens, and ragweed-specific IgE and IgG antibody responses were measured at the same intervals as the challenges and at the end of the study. The effect of the therapy on clinical symptoms was not evaluated. Before therapy the groups of adults and children were comparable by all indices, except for TAME esterase activity in nasal washes during ragweed nasal challenge which was significantly lower in children. During treatment, mediators released during sequential nasal challenges declined to undetectable levels in most patients and changes in nasal ragweed sensitivity were comparable in both groups. Ragweed IgE increases after 12 weeks of therapy and IgG levels at maintenance therapy tended to be higher in the children, but neither difference was statistically significant. At the end of the study IgE and IgG antibody levels were comparable in both groups. Results of methacholine inhalation tests did not change significantly in either group. The decrease in skin sensitivity to ragweed was similar in both groups. We conclude that ragweed immunotherapy leads to immunological and biological consequences that are comparable in children and adults.