Changes in nasal specific IgE to mites after periods of allergen exposure-avoidance: a comparison with serum levels

Nasal and Serum Immunoglobulin E Levels in Symptomatic Allergic Rhinitis Patients: A Case-Control Study

Allergic Rhinitis (AR) is an inflammatory condition of the nasal mucosa triggered by Immunoglobulin E (IgE) mediated response to exposure to allergens. The most common symptoms are nasal obstruction, sneezing, runny nose and these in addition to swollen, itchy, red and watery eyes. Recent studies have shown highly elevated immunoglobulin E levels in the airway mucosa independently of serum IgE levels and atopic status. Nasal mucosa has intrinsic capability to produce IgE in allergic rhinitis. The study was conducted to explore the levels of nasal total IgE and serum total IgE and their correlation in symptomatic AR patients. This was a case control-study and two groups participated in the study. The first group included 203 symptomatic patients who were diagnosed in the otorhinolaryngology clinic as cases of AR, known as AR group. The second group was control group and included 203 apparently healthy volunteers without any history suggestive of AR. The associated risk factors for severe allergic symptoms were assessed by logistic regression model. The mean differences between nasal total IgE and serum total IgE levels of both groups were compared by t-test. A correlation was investigated between nasal IgE and serum IgE in both the groups. The mean level of nasal total IgE and serum total IgE was found to be 103.9 and 291.4 IU/ml in AR group, respectively, and 17.5 and 67.5 IU/ml in the control group, respectively. Levels of nasal total IgE and serum total IgE were significantly higher in the nasal fluids and serum of symptomatic allergic rhinitis patients than in controls (p < 0.001 and < 0.001 respectively). A logistic regression model showed severity of allergic rhinitis was significantly associated with nasal total IgE levels. The correlation of nasal total IgE levels with serum total IgE levels in the control group was found to be statistically insignificant. However a statistically positive correlation was observed between nasal total IgE and serum total IgE levels in the AR group. It is possible that nasal IgE and serum IgE interact in the pathogenesis of AR and this is evident in the current study. Nasal IgE levels should be evaluated in severe symptomatic allergic rhinitis patients. The interaction between nasal IgE to serum IgE levels should be further investigated in AR patients for other possible prevalent endotypes of AR.

Challenges in Local Allergic Rhinitis Diagnosis, Management, and Research: Current Concepts and Future Perspectives

Local allergic rhinitis (LAR) is diagnosed based on the presence of clinical symptoms such as rhinorrhea, sneezing, and nasal itching using negative skin prick testing and serum IgE assessment. Several novel studies have shown that it is possible to use the assessment of nasal sIgE (specific immunoglobulin E) secretion as an additional diagnostic criterion for local allergic rhinitis. Additionally, allergen immunotherapy is a promising-albeit still not fully assessed and evaluated-future method of managing patients with LAR. In this review, the historical background, epidemiology, and main pathophysiological mechanisms of LAR shall be presented. Additionally, we address the current state of knowledge based on selected articles regarding the assessment of the local mucosal IgE presence in response to exposure to such allergens as mites, pollen, molds, and others. The impact of LAR on quality of life as well as the possible options of management (including allergen immunotherapy (AIT), which showed promising results) will then be presented.

Atopy in Kashmir-validation from a case control study with respect to IgE and Interleukin genes

OBJECTIVES

Increased levels of serum Immunoglobulin-E (IgE) and different genetic variants of cytokines are common biochemical manifestation in Allergy. The current study was aimed to study the association of IgE and different variants of Interleukin-4 (IL-4), and Interleukin-13 (IL-13) genes with different kind of allergies.

METHODS

A pre-tested questionnaire was used to collect all the dietary, life style and clinical details by a trained staff. A blood sample of 2 ml each was collected in coagulated and anti-coagulated vials. DNA and serum samples were extracted and stored until further use. Serum IgE were estimated by ELISA while as the genotypic analysis was done by PCR-RFLP methods.

RESULTS

Statistically a significant difference of serum IgE levels were observed among cases and controls (P < 0.05). The observed significant difference of serum IgE levels were retained among subjects who also harboured variant genotypes of IL-4 and IL-13 genes (P < 0.05). Additionally, the above genetic variants significantly modified the risk of allergy when stratification was done based on various clinical characteristics.

CONCLUSION

Our study suggests that increased IgE levels and in association with variant forms of IL-4 and IL-13 genes are significantly associated with different types of allergies in study population.

B cells and upper airway disease: allergic rhinitis and chronic rhinosinusitis with nasal polyps evaluated

Introduction: The first mucosal site to encounter inhaled allergen, antigen, and microbes is the upper airway. It must perforce have a rapid system of environmental threat recognition and self-defense. B cells play a critical role in such airway host-defense, tissue surveillance, and immune modulation. Several common upper airway diseases can be defined in the expression of either exaggerated or dysregulated B-cell function within T2-high mucosal inflammatory states.Areas covered: In this review, the authors discuss the immunology of allergic rhinitis (AR) and chronic rhinosinusitis with nasal polyps (CRSwNP) in the context of highlighting key aspects of B-cell biology and function. The review is based on the findings of a literature search using the terms B cells, rhinitis, nasal polyps, and rhinosinusitis.Expert opinion: Despite the emerging role of B-cell overdrive and dysfunction in upper airway disease, studies are lacking specifics to B cells, particularly in association with sinonasal infection and mucosal inflammation. There is a pressing need to focus on how respiratory inflammation, alongside impaired or exaggerated B-cell function, amplifies and further dysregulates immune signaling pathways in the disease setting of AR and CRSwNP.

Dramatically decreased T cell responses but persistent IgE upon reduced pollen exposure

Mugwort pollen allergy is frequent in parts of Europe. As mugwort pollen contains only one major allergen, Art v 1, which harbors only one T cell epitope, we employed mugwort pollen allergy as a model to study allergen-specific T cell responses. However, after 2004, we noticed a drastic decrease in the T cell responses to Art v 1 and eventually it became almost impossible to detect allergen-specific responses at the T cell level in mugwort-allergic individuals. To explain this observation, we retrospectively investigated the local exposure to mugwort pollen and its possible correlation to the frequency and reactivity of allergen-specific T cells. The total annual pollen indices dramatically dropped after 2004 and never reached previous levels again. Local sensitization to mugwort pollen and serum IgE antibodies specific for Art v 1 remained unchanged until 2015. Our mugwort pollen model shows that specific IgE-levels are maintained for extremely long time periods in spite of a long-term reduction of natural allergen exposure to levels that are too low to boost specific T cells.

IgE Test in Secretions of Patients with Respiratory Allergy

PURPOSE OF REVIEW

IgE is a key player in multiple inflammatory airway diseases. Ample literature demonstrates its presence in mucosa of patients with allergic rhinitis (AR), local allergic rhinitis (LAR), asthma, or chronic rhinosinusitis with nasal polyposis (CRSwNP).

RECENT FINDINGS

Current evidence shows that high-affinity IgE in blood stream of allergic individuals derives mainly from the mucosae. Also, mucosal synthesis of IgE can occur in the absence of systemic atopy, and may be relevant in atopic and non-atopic phenotypes of rhinitis as demonstrated in LAR. Specific IgE (sIgE) detection varies depending on technique used for sample collection and its measurement. sIgE detection is highly specific for diagnosis of LAR. Moreover, measurement of sIgE in secretions could be useful in monitoring response to allergen-specific immunotherapy in both AR and LAR phenotypes. This review will focus on recent developments in the role of IgE in respiratory diseases, and the clinical implications of its measurement in secretions.

International Consensus Statement on Allergy and Rhinology: Allergic Rhinitis

BACKGROUND

Critical examination of the quality and validity of available allergic rhinitis (AR) literature is necessary to improve understanding and to appropriately translate this knowledge to clinical care of the AR patient. To evaluate the existing AR literature, international multidisciplinary experts with an interest in AR have produced the International Consensus statement on Allergy and Rhinology: Allergic Rhinitis (ICAR:AR).

METHODS

Using previously described methodology, specific topics were developed relating to AR. Each topic was assigned a literature review, evidence-based review (EBR), or evidence-based review with recommendations (EBRR) format as dictated by available evidence and purpose within the ICAR:AR document. Following iterative reviews of each topic, the ICAR:AR document was synthesized and reviewed by all authors for consensus.

RESULTS

The ICAR:AR document addresses over 100 individual topics related to AR, including diagnosis, pathophysiology, epidemiology, disease burden, risk factors for the development of AR, allergy testing modalities, treatment, and other conditions/comorbidities associated with AR.

CONCLUSION

This critical review of the AR literature has identified several strengths; providers can be confident that treatment decisions are supported by rigorous studies. However, there are also substantial gaps in the AR literature. These knowledge gaps should be viewed as opportunities for improvement, as often the things that we teach and the medicine that we practice are not based on the best quality evidence. This document aims to highlight the strengths and weaknesses of the AR literature to identify areas for future AR research and improved understanding.

Local Allergic Rhinitis in Pediatric Patients: Is IgE Dosage in Nasal Lavage Fluid a Useful Diagnostic Method in Children?

Local Allergic Rhinitis (LAR) is an emerging disease. However, its incidence in the pediatric popolution has not yet been studied. The gold standard for the diagnosis is the nasal provocation test that is not everywhere avalaible and difficult to apply in children. The aim of our study was to evaluate the nasal lavage fluid IgE as a biomarker of LAR in children. 54 pediatric patients [IQR 4.0-12.0 years] were divided into 3 groups: study group (26 children with rhinitis symptoms and without evidence of systemic atopy); allergic rhinitis (AR) group (15 children) and 13 healty controls (HC). Every child was subjected to nasal lavage using 2 ml/nostril of physiologic saline solution, that was therefore analyzed by ImmunoCAP to obtain the IgE concentration. Rhinofibroscopy and nasal cytology were performed. Our data showed the presence of higher value of nasal lavage fluid IgE (average of 6.005 UI/ml; range: 4.47-7.74 UI/ml) in 16 out of 26 patients of the study group who therefore may be classified as affected by LAR. We observed a statistically significant difference (P< 0.0001) between NAR/HC group and LAR group, identifying a cut-off of 3.85 UI/ml. Finally, we found a better response to previous AR therapy in the LAR group than in the NAR group. Our data showed the high incidence of LAR in pediatric patients previously classified as NAR. The measurment of IgE in nasal lavage fluid may be considered an easy and rapid method for the diagnosis of LAR in children. Besides, our data add confirmatory evidence about the good response of LAR children to the classic AR therapy.

The role of local allergy in the nasal inflammation

Local allergic inflammation (LAI) is recognized recently. 'entopy' was used to define LAI, which was positively correlated with allergen provocation testing, local sIgE up-regulation, inflammatory mediator secretion, and a lack of systemic allergy. The study of LAI is in its infancy and focuses mainly on the respiratory system. It is closely related to nasal inflammation and plays important roles in patients with nonallergic rhinitis (NAR), nonallergic chronic sinusitis with nasal polyps (CRSwNP), and nonallergic fungal rhinosinusitis (NAFRS). Based on studies using nasal allergen provocation testing, 40-57% of patients with NAR exhibited positive results and could be diagnosed as local allergic rhinitis. Total IgE and common airborne allergen-sIgE were up-regulated in eosinophilic CRSwNP patients compared to noneosinophilic CRSwNP patients and healthy controls, possibly due to local allergic inflammation. Some researchers also found that the level of local sIgE was increased in patients with NAFRS; they suggested that local allergic inflammation occurs in NAFRS. Studies of LAI will increase our understanding of nasal inflammation and help to establish novel treatments. However, the diagnosis of local allergic inflammation is complex due to the lack of convenient detection methods. The relationship between local allergic inflammation and systemic allergic inflammation is unclear, and an appropriate treatment for local allergic inflammation is required.

Nonallergic rhinitis and lower airway disease

In the past years, several investigators have demonstrated the existence of local nasal responses in some patients with typical allergic rhinitis symptoms but without atopy and have defined a new phenotype called local allergic rhinitis (LAR) or 'entopy'. In a percentage of LAR subjects, the upper airway disease is also associated with lower airway symptoms. After the description of this phenotype, the differential diagnosis between LAR and nonallergic rhinitis (NAR) has become a challenge for the clinician. To correctly identify LAR patients is of high importance for treatment and management of these patients, and for an appropriate inclusion of patients in clinical trials and genetics studies. The treatment of LAR patients, in contrast with NAR, is oriented to allergen avoidance and specific treatment. Allergen immunotherapy, the aetiological treatment for allergic respiratory diseases, has demonstrated to be an effective and safe treatment in LAR, increasing immunological tolerance, and reducing the clinical symptoms and the use of medication. In this article, the important and novel aspects of LAR in terms of mechanisms, diagnosis and treatment will be discussed. Also, the involvement of the lower airway and the potential role of IgE in the bronchial disease will be also reviewed.

Local allergic rhinitis: A critical reappraisal from a paediatric perspective

The so-called local allergic rhinitis (LAR) has been proposed as a phenotype of rhinitis with Th2-driven prominent local allergic inflammation, nasal synthesis of specific IgE and a positive response to a nasal allergen provocation test, in the absence of 'systemic' atopy (negative skin prick test and serum allergen-specific IgE antibodies). To date, available data on LAR are mostly focused on adults. The purpose of this 'Rostrum' was to critically discuss data and implications of the 'LAR concept' in paediatrics. In the natural history of rhinitis due to IgE-mediated reactions triggered by exposure to allergens, a 'LAR' can be either the initial, transient stage of classical allergic rhinitis or a stable phenotype never evolving to 'systemic' IgE sensitization. Given the present difficulties in performing routinely nasal allergen provocation test in children, the development of sensitive and specific tests to detect IgE in the child's nasal secretions is a research priority. We suggest also the hypothetical role of allergen immunoprophylaxis or immunotherapy in LAR. Last, the term 'local allergic rhinitis' may be inappropriate, as rhinitis is always 'local', while IgE sensitization can be either 'local' or 'systemic'.

Local IgE in non-allergic rhinitis

Local allergic rhinitis (LAR) is characterized by the presence of a nasal Th2 inflammatory response with local production of specific IgE antibodies and a positive response to a nasal allergen provocation test (NAPT) without evidence of systemic atopy. The prevalence has been shown to be up to 25% in subjects affected with rhinitis with persistence, comorbidity and evolution similar to allergic rhinitis. LAR is a consistent entity that does not evolve to allergic rhinitis with systemic atopy over time although patients have significant impairment in quality of life and increase in the severity of nasal symptoms over time. Lower airways can be also involved. The diagnosis of LAR is based mostly on demonstration of positive response to NAPT and/or local synthesis of specific IgE. Allergens involved include seasonal or perennial such as house dusts mites, pollens, animal epithelia, moulds (alternaria) and others. Basophils from peripheral blood may be activated by the involved allergens suggesting the spill over of locally synthesized specific IgE to the circulation. LAR patients will benefit from the same treatment as allergic patients using antihistamines, inhaled corticosteroids and IgE antagonists. Studies on immunotherapy are ongoing and will determine its efficacy in LAR in terms of symptoms improvement and evolution of the natural course of the disease.

Local immunoglobulin e in the nasal mucosa: clinical implications

Immunoglobulin E (IgE) can be highly elevated in the airway mucosa independently of IgE serum levels and atopic status. Mostly, systemic markers are assessed to investigate inflammation in airway disease for research or clinical practice. A more accurate but more cumbersome approach to determine inflammation at the target organ would be to evaluate markers locally. We review evidence for local production of IgE in allergic rhinitis (AR) and chronic rhinosinusitis with nasal polyps (CRSwNP). Diagnostic and therapeutic consequences in clinical practice are discussed. We describe that the airway mucosa has the intrinsic capability to produce IgE. Moreover, not only do IgE-positive B cells reside within the mucosa, but all tools are present locally for affinity maturation by somatic hypermutation (SHM), clonal expansion, and class switch recombination to IgE. Recognizing local IgE in the absence of systemic IgE has diagnostic and therapeutic consequences. Therefore, we emphasize the importance of local IgE in patients with a history of AR or CRSwNP.

Casein-specific IL-4- and IL-13-secreting T cells: a tool to implement diagnosis of cow's milk allergy

BACKGROUND

Cow's milk allergy (CMA) is a frequent food allergy in young children. The oral food challenge is the gold standard for diagnosis, and there is currently no reliable biological test. Our aim was to evaluate the diagnostic potential of a functional assay quantifying allergen-specific Th2 cells in CMA children.

METHODS

A total of 29 children aged 2.8-10.5 years underwent a double-blind, placebo-controlled food challenge (DBPCFC) to cow's milk. Blood was collected before performing the DBPCFC, and peripheral mononuclear cells were cultured in an 18-h ELISpot assay with casein, α-lactalbumin, or β-lactoglobulin. Numbers of antigen-specific IL-4- and IL-13-secreting lymphocytes and serum-specific IgE, IgG4, and total IgE levels were assessed. Receiver operating characteristic (ROC) curves were generated.

RESULTS

A total of 17 (59%) children reacted to cow's milk and were therefore considered as allergic to cow's milk (CMA). The mean number of casein-specific IL-4- and IL-13-secreting T cells was higher in CMA than in non-CMA children (P = 0.009, 0.004, respectively). Moreover, it was inversely correlated with the cumulative dose of cow's milk tolerated (P = 0.003, 0.0009, respectively). ROC curve of combined IL-4 and IL-13 analysis showed an area under the curve of 0.98 (95% CI 0.90-1.06). For a cutoff of 10 IL-4- and 12 IL-13-secreting T cells, sensitivity and negative predictive value were 100%.

CONCLUSIONS

Enumeration of casein-specific IL-4- and IL-13-secreting T cells appears a promising tool to improve diagnosis and, if confirmed in larger studies, could permit less frequent use of the oral food challenge.

Quantification of circulating house dust mite-specific IL-4- and IL-13-secreting T cells correlates with rhinitis severity in asthmatic children and varies with the seasons

BACKGROUND

Defining suitable markers to diagnose and monitor allergy and its severity is essential to correctly assign patients for specific immunotherapy. Circulating levels of specific IgE are good markers of sensitization, but not of clinically symptomatic allergy.

OBJECTIVE

To quantify circulating interleukin (IL)-4- and IL-13-secreting T cells specific for house dust mite (HDM) in children presenting HDM-allergic asthma associated or not with rhinitis and correlate results with clinical symptoms.

METHODS

We analysed 26 children with HDM respiratory disease (allergic rhinitis and asthma) together with six children with non-allergic asthma. Peripheral blood mononuclear cells were stimulated with HDM extract in a 24-h ELISpot assay to quantify the number of HDM-specific IL-4- and IL-13-secreting T cells. Asthma severity and control, and rhinitis severity were scored according to the Global Initiative for Asthma (GINA) and the Allergic Rhinitis and its Impact on Asthma (ARIA) Guidelines.

RESULTS

The number of HDM-specific IL-4- and IL-13-secreting T cells was higher in patients with allergic asthma as compared to patients with non-allergic asthma. It varied with the season of blood sampling with two peaks in the fall and early spring. Independently of the season, the number of HDM-specific IL-4-secreting T cells correlated with rhinitis severity (OR = 2; 95% IC:1.1-3.8; P = 0.04).

CONCLUSIONS AND CLINICAL RELEVANCE

Allergen-specific IL-4- and IL-13-producing T cells were only detected in HDM-allergic asthmatic children (not in patients with non-allergic asthma). Their numbers correlated with clinical severity of allergic rhinitis.

Encasing bedding in covers made of microfine fibers reduces exposure to house mite allergens and improves disease management in adult atopic asthmatics

BACKGROUND

Studies of avoidance of exposure to group 1 allergens of the Dermatophagoides group (Der p 1) have not yielded consistent improvements in adult asthma through avoidance. We explored whether the use of pillow and bed covers and allergen-avoidance counseling resulted in Der 1-level reduction, as measured by enzyme-linked immunosorbent assay, and thus improved asthma symptoms in adult patients.

METHODS

Twenty-five adult patients with moderate or severe atopic asthma were randomized into intervention and control groups. Intervention patients slept on pillows and mattresses or futons encased in microfine-fiber covers and were counseled in allergen avoidance through bedroom cleaning. Control patients received neither special covers nor counseling. In the period August to October in 2009 (pre-intervention) and 2010 (post-intervention), dust samples were collected in open Petri dishes placed in bedrooms for 2 weeks and by rapid lifting of dust from bedding and skin using adhesive tape on the morning of 1 day of Petri dish placement. We examined the associations between changes in Der 1 level (as measured by enzyme-linked immunosorbent assay) and clinical symptom score, minimum % peak expiratory flow, and fraction of exhaled nitric oxide.

RESULTS

Der 1 allergen levels on the mattress/futon covers and near the floor of the bedrooms of intervention patients, but not controls, were lower in 2010 than in 2009. From 2009 to 2010, asthma symptom scores decreased significantly, and minimum % peak expiratory flow increased significantly, in intervention patients. The fall in Der p 1 concentration was correlated with a reduction in the fraction of exhaled nitric oxide.

CONCLUSIONS

Minimization of Der 1 allergen exposure by encasing pillows and mattresses or futons and receiving counseling on avoiding exposure to indoor allergens improved asthma control in adult patients.

A comparison between IgE and IgG4 as markers of allergy in children: an experimental trial in a model of natural antigen avoidance

IgG4 have been hypothesized to act as blocking antibodies capable of preventing IgE-mediated effector cell triggering. This study aims to evaluate the changes in IgG4 in children during a period of natural antigen avoidance. Serum IgE and IgG4 were evaluated in a group of asthmatic children, aged between 7 and 17 years, admitted to the residential house Istituto Pio XII (Misurina, BL, Italy), located at 1,756 m, in a natural model of antigen avoidance. All the patients were skin prick test positive to at least two of the following allergens: Dermatophagoides pteronissynus, Dermatophagoides farinae, cat epithelium, timothy grass pollen and Parietaria pollen. During the 180 days of hospitalization, serum specific IgE and IgG4 were measured six times. A significant decrease (p&#x2264;0.05) in serum specific IgE to house dust mite and pollen allergens was observed; by contrast, no significant variations were shown by IgG4 and IgG4/IgE ratio. No significant relationship was found between serum specific IgE, IgG4 and IgG4/IgE ratio variations and the re-exposure to house dust mite allergens during the Christmas holidays. A positive correlation between specific IgE and specific IgG4 was observed at each considered time (T0: r=0.57, p=0.08; T1: r=0.85, p=0.001; T3: r=0.76, p=0.01). The positive correlation between specific IgE and specific IgG4, enduring throughout the entire time of study, suggests a relationship between these classes of immunoglobulins.

Germinal-centre reactions in allergic inflammation

Primary and secondary immune responses in the germinal centres of lymphoid organs have been studied in the past. There is now compelling evidence of a third stage in the immune response, in 'tertiary lymphoid organs' that develop at sites of chronic inflammation in response to persistent local antigen challenge. Germinal-centre-like reactions are well-documented in the target organs of autoimmune diseases. Here, we review recent evidence that they also occur at sites of allergic inflammation.

Do tryptase, ECP and specific IgE measurement by nasal incubation increase the specific nasal provocation test sensitivity?

The specific Nasal Provocation Test (sNPT) is a third level diagnostic tool. Fitted to reproduce natural exposure condition to pick the responsible allergen for nasal symptoms out, it is applied when prick test and RAST responses are doubtful. SNPT results have been evaluated measuring nasal resistance (anterior rhinomanometry) and nasal symptoms (clinical score), reaching 50% of sensitivity. This study focused on the determination of allergic response markers, triggered by nasal challenge: tryptase levels in the nose, specific IgE and ECP (Eosinophil Cationic Protein). The aim was to increase sNPT sensitivity. Twenty patients suffering from allergic rhinitis and 16 age-matched-nonallergic subjects were enrolled in the study. Tryptase, specific IgE and ECP were determined in nasal mucosa applying a new method, based on in situ incubation, before and after sNPT. The latter was performed following a standardized method. Tryptase levels increased in 13 patients (65%), were unchanged in four patients (20%), and slightly decreased in three patients (15%). The increase recorded was significant in mite allergic patients (p=0.005), but not significant (p> 0.05) in pollen allergic patients. ECP values increased in 13 patients (65%), were unchanged in two patients (10%), and highly decreased in five patients (25%). ECP increase was not significant (p> 0.05). Specific IgE levels increased in seven patients (35%), were unchanged in 11 patients (55%) and decreased in two patients (10%). The IgE increase was significant in pollen-allergic patients (p<0.05), while it was not significant in mite-allergic patients (p>0.05). Tryptase, ECP, and specific IgE were not detected in the control group. The data obtained showed a positive sNPT response in 12 patients (60%). Comparing our results with those derived from classical-parameter employment, we gathered an improvement of 10%. On the basis of the usual parameters, in fact, we recorded 50% positivity, while the use of mediators provided an additional 10% improvement in sNPT sensitivity: taking together the usual parameters and nasal allergic mediators values, we reached an sNPT over-all sensitivity of 85%.

Clinical value and measurement of specific IgE

The diagnosis of human allergic diseases involves the combined use of a careful clinical history, physical examination, and in vitro and in vivo assay methods for the detection of IgE antibodies of defined allergen specificities. In vivo (skin testing) and in vitro (measurement of specific IgE in serum) techniques cannot be considered interchangeable, the former reflecting not only the presence of IgE but also mast cell integrity, vascular and neural responsiveness. Both techniques have similarities and differences, advantages and disadvantages. Recently introduced "second generation" immunoassays have continued to improve the analytical sensitivity and reproducibility thanks to automation and improved reagent quality. Quantitative assays may allow the use of specific clinical thresholds able to differentiate symptomatic from asymptomatic patients. False-negative and false-positive results should derive from lability of some major extracts, and from possible cross-reactivities, respectively. Characterization of allergens at a molecular and submolecular level and, where necessary, the use of recombinant allergens can reduce cross-reactions and further improve the quality of immunoassays.

Local IgE synthesis in allergic rhinitis and asthma

Local IgE production has been a contentious concept for over 40 years. Although a host of clinical observations suggested a local source of IgE, co-localization of IgE to B cells in the nasal mucosa could not be demonstrated. In contrast, igE-producing B cells were observed in local lymphoid tissue. Definitive proof of local IgE synthesis in the nasal mucosa has now become available. Here, we review the recent developments in local IgE research in allergic rhinitis and asthma within their historical context, and speculate on the implications of both local IgE synthesis and ongoing research into local immunoglobulin isotype switching for patient therapy.

Increases in allergen-specific IgE in BAL after segmental allergen challenge in atopic asthmatics

IgE is important in both early and late allergic responses. Increases in the numbers of RNA transcripts coding for IgE have been observed in the bronchial mucosa of asthmatics and in the nasal mucosa of hay fever patients both during natural allergen exposure and after nasal allergen challenge, suggesting that IgE may be synthesized locally in the mucosa. In this study we have examined bronchoalveolar lavage (BAL) taken before and 24 h after bronchoscopic segmental allergen challenge from 18 atopic asthmatic patients, looking for evidence of increases in IgE protein. Allergen-specific IgG and total and allergen-specific IgE were measured in BAL using a fluoroenzyme immunoassay. There was a significant increase in allergen-specific IgE (Ku/L) in the BAL after allergen challenge [before [median (interquartile range)] 0 (0, 0); after 0.35 (0, 1.87): p = 0.009] which was not observed for allergen-specific IgG (p = 1.0) or for IgE specific to an allergen to which the subject was sensitized but was not used for provocation (p = 1.0). Correction for corresponding increases in total IgE, albumin, and urea in BAL did not affect the observed changes in allergen-specific IgE. These data indicate that allergen provocation results in a selective local accumulation of isotype-specific and allergen-specific IgE antibody within the bronchi, independent of alterations in circulating IgE.

Local expression of epsilon germline gene transcripts and RNA for the epsilon heavy chain of IgE in the bronchial mucosa in atopic and nonatopic asthma

BACKGROUND

The demonstration of epsilon germline gene (Cepsilon) transcripts and mature mRNA for the epsilon heavy chain gene (Iepsilon) in the nasal mucosa suggested that IgE synthesis may occur in allergic rhinitis.

OBJECTIVE

In view of our previous demonstration of increases in IL-4 mRNA(+) cells in asthmatic subjects, we assessed whether local IgE synthesis may also be a feature of bronchial asthma.

METHODS

Fiberoptic bronchoscopic mucosa biopsy specimens were obtained from 9 atopic asthmatic subjects and 10 nonatopic normal (intrinsic) control subjects. To control for atopy, we also studied 9 nonatopic asthmatic subjects and 10 atopic nonasthmatic control subjects. Tissue was processed for immunohistochemistry for B cells (CD20) and in situ hybridization for Iepsilon and Cepsilon RNA(+) cells and IL-4 mRNA(+) cells.

RESULTS

B-cell numbers in the bronchial mucosa were similar for asthmatic subjects compared with control subjects, whereas significantly higher numbers of Iepsilon RNA(+) (P =.02 and P =.04, respectively), Cepsilon RNA(+) (P =.01 and P =.03, respectively), and IL-4 mRNA(+) (P =.001 and P =.001, respectively) cells were observed in atopic asthmatic subjects and nonatopic asthmatic subjects, respectively, but not in atopic control subjects compared with nonatopic control subjects. In asthmatic subjects there were significant correlations between Iepsilon RNA(+) cells (r = 0.54, P =.02) and Cepsilon RNA(+) cells (r = 0.48, P =.05) when compared with the number of IL-4 mRNA(+) cells.

CONCLUSION

Increases in Iepsilon and Cepsilon RNA(+) cells, but not B-cell numbers, in the bronchial mucosa provide evidence for local IgE synthesis in both atopic and nonatopic asthma. These changes appear to relate to asthma rather than atopy per se and, at least in part, may be under the regulation of IL-4.

Eosinophil cationic protein and specific IgE in serum and nasal mucosa of patients with grass-pollen-allergic rhinitis and asthma

BACKGROUND

After allergen exposure, IgE-bearing mast cells surface in respiratory mucosa. Eosinophils are also recruited locally by chemotactic mediators; they are the main cell directly involved in the late phase of allergic inflammation. IgE antibody and eosinophil cationic protein (ECP) are routinely determined mainly in serum although they exert their pathogenetic role more directly on mucosal surfaces.

METHODS

We performed a comparative study of IgE antibody to grass and ECP on nasal mucosa and blood samples in order to evaluate the relevance of monitoring allergic inflammation in the target organ. Thirty-one patients and 10 nonatopic controls were enrolled in the protocol. Twenty-six subjects allergic to grass, 11 with rhinitis (group 1) and 15 with asthma and rhinitis (group 2), completed the study. Five patients dropped out. Specific IgE to grass and ECP was determined in nasal mucosa by our method based on in situ incubation.

RESULTS

Serum IgE to grass did not increase during the pollen peak, as did nasal IgE, in group 1 from before the pollen peak, from 2.3 to 3.2 kU/l (P=0.02), and in group 2 at the pollen peak, from 4.8 to 12.2 kU/l (P=0.01). Serum ECP did not show any significant variation in group 1, but it increased at pollen peak from 6 to 11.2 microg/l (P=0.01) in group 2. Nasal ECP increased significantly in both groups even before the pollen peak. In group 1, ECP values rose from 15 to 39.9 microg/l (P=0.01). In group 2, ECP increase was much higher than in group 1, from 9 to 213 microg/l (P=0.001). Serum eosinophils, like nasal ECP, showed a significant increase of values from before the pollen peak in both groups, without correlation with serum ECP in rhinitic patients.

CONCLUSIONS

Both specific IgE and ECP in the nasal mucosa showed a better correlation with allergen exposure than serum evaluations. With an appropriate method, allergic inflammation may be best monitored in the nasal mucosa.

Quantitative IgE antibody assays in allergic diseases

During the past several years, immunoassays for specific IgE antibodies have been refined to permit reporting results in mass units. Thus quantitative immunoassays for IgE antibodies may be an adjunct to skin tests. In cases of food allergy among children with atopic dermatitis, cutoff values for IgE antibody concentrations to egg, milk, peanut, and fish have been derived to provide 95% positive and 90% negative predictive values. Food-specific IgE antibody determinations can also be used to predict which food allergies are resolving spontaneously. Elevated egg-specific IgE antibody levels in infancy are associated with significantly increased risk for development of inhalant allergies later in childhood. In cases of inhalant allergy, specific IgE antibody levels correlate closely with results of inhalation challenge studies in cat-sensitive persons. Also, mite-specific IgE antibody levels correlate significantly with the mite allergen contents of reservoir dust in the homes of mite-sensitive persons. Immunoassays for quantitation of specific IgE antibodies may be used to document allergen sensitization over time and to evaluate the risk of reaction on allergen exposure. However, immunoassays and skin tests are not entirely interchangeable, and neither will replace the other in appropriate circumstances.

House-dust-mite sublingual-swallow immunotherapy (SLIT) in perennial rhinitis: a double-blind, placebo-controlled study

BACKGROUND

The safety and efficacy of sublingual-swallow immunotherapy (SLIT) in rhinitis caused by house-dust mite were evaluated in a double-blind, placebo-controlled study including 75 patients for 24 months.

METHODS

Patients received either placebo or SLIT with a standardized Dermatophagoides pteronyssinus (D.pt.) - D. farinae (D.f) 50/50 extract. The mean cumulative dose was 90,000 IR, equivalent to 2.2 mg of Der p 1 and 1.7 mg of Der f I. Symptom and medication scores were assessed throughout the study. Exposure to house-dust mite, skin sensitivity, and serum specific IgE and IgG4 were assessed before starting treatment and after 12 and 24 months.

RESULTS

Seventy-two patients (36 active-36 placebo) were eligible for intent-to-treat analysis. Thirty-six patients dropped out of the study. The number of patients who dropped out due to lack of efficacy was eight out of 37 (21.6%) in the active treatment group compared to 15 out of 38 (39.5%) in the placebo group (chi-square=2.81, P=0.09). Total symptom and medication scores decreased significantly after 12 and 24 months (P<0.05) of treatment in both groups, but no significant difference was observed between the active and placebo groups. After 24 months, the number of patients with high levels of indoor allergenic load decreased significantly in both groups compared to baseline data (P=0.01). Specific IgE (D.pt. and D.f.) increased significantly in the active treatment group after 12 and 24 months, while no change was observed in the placebo group. Specific IgG4 levels were not significantly modified in either group. Two patients in each group reported mild adverse effects. No severe adverse effects were reported.

CONCLUSIONS

We conclude that SLIT in rhinitis caused by house-dust mite was safe, but there was a lack of consistent clinical benefit compared to placebo, probably due to the impact of the allergen avoidance measures that lowered the allergen burden.

Methods and effectiveness of environmental control

In recent years the role of allergen exposure and atopy, and the interaction between them in the clinical expression of allergic disease, has been examined in a quantitative manner in epidemiologic studies. Such analyses suggest that avoidance of exposure to domestic allergens is a critical element in integrated strategies for both the prevention and the management of asthma. The promise of primary intervention in high-risk infants, as shown in the Isle of White study, has been confirmed in a recent study in Japan, and at least 4 similar trials are in progress. Applying these principles to the management of symptoms in patients with chronic asthma has proved more difficult, and it is likely that many earlier studies were poorly designed to test the hypothesis that allergen avoidance was clinically useful. Recent studies with patients moved to high altitudes during seasonal reductions in mite exposure and randomized controlled interventions in houses have all shown improvements in clinical manifestations of asthma. These recent trials have also demonstrated something that was less certain-that massive reductions in domestic allergen exposure can be achieved and that people will adopt the significant changes to their domestic environment and lifestyles if the risks and benefits are known. In the future, it seems likely that better study designs, as well as improvements in methods to monitor exposure and clinical outcomes, will provide further support for the role of allergen avoidance in the prevention and management of asthma.

The role of IgE in asthma

Asthma is a multifactorial and complex disease in which allergic factors and non-allergic triggers interact and result in bronchial obstruction and inflammation. Allergenic sensitization is important in the development of asthma and, although links between inhalant allergy and asthma have been known for many years, they have recently been re-emphasized. Indoor allergens are associated with asthma prevalence, severity and exacerbations whereas outdoor allergens such as pollens are associated with exacerbations. Moreover, there is a link between total IgE and asthma which appears to be independent of allergen sensitization. One of the typical aspects of airway inflammation of asthma is the infiltration of the airway wall by T helper type 2 (Th2) cells. These cells are attracted to inflammatory sites by adhesion molecules and chemokines among which CCR3 and CXCR4 receptors appear to be of importance. Differentiation of B cells into IgE-secreting plasma cells is a complex cascade of events in which cytokines play a crucial role. Both IL-4 and IL-13 are inducing IgE synthesis whereas IFN-gamma and IL-12 are blocking IgE synthesis. IgE production by B cells not only requires the presence of IL-4 or IL-13, but also a physical interaction between T and B cells, involving a number of surface and adhesion molecules such as CD40-CD40L and CD28/CD80. Production of TH2-cytokines is not restricted to T cells as basophils and mast cells can produce them indicating that these cells may be of importance in the synthesis of IgE.

Analysis of induced sputum for studying allergen-specific IgE antibodies in airway secretion from asthmatic patients

BACKGROUND

Allergen-specific IgE antibodies have been considered to play an important role in the pathogenesis of atopic asthma. However, studies on allergen-specific IgE antibodies in airway secretion from asthmatic patients are very rare compared with those in serum.

OBJECTIVES

The present study was undertaken to determine whether induced sputum might provide a useful method for analysing allergen-specific IgE antibodies in airway secretions from asthmatic patients.

METHODS

Specific IgE antibodies to house dust mite (HDM) antigen were measured in induced sputum from 10 HDM-sensitive asthmatic patients and 12 non-allergic controls by enzyme-linked immunosorbent assay. HDM-specific IgE was regarded as positive when the absorbance value was higher than mean + 2SD of controls. Their antigen-binding characteristics were determined by immunoblot analysis.

RESULTS

HDM-specific IgE was positive in induced sputum from seven of 10 HDM-sensitive asthmatics. The IgE binding to HDM antigen could be inhibited by fluid phase HDM antigen in a dose-dependent manner, not by mugwort antigen. Treatment of induced sputum with dithiothreitol decreased the antigen-specific bindings, and increased the non-specific bindings on the measurement of HDM-specific IgE. These effects were significant in a concentration of dithiothreitol greater than 0.05%. Immunoblot analysis revealed that HDM-specific IgE antibodies in induced sputum recognized the HDM antigens with molecular weights of 42, 34, 32, 25 and 14 kDa. These antigen binding characteristics were similar to those in serum.

CONCLUSION

We conclude that analysis of induced sputum is a useful non-invasive method for studying allergen-specific IgE antibodies in airway secretion from asthmatic patients.

Seasonal variation of IgG subclass antibodies to house dust mite in sera from mite-sensitive asthmatic patients

BACKGROUND

House dust mite is an important cause of bronchial asthma. Seasonal variation of environmental house dust mite allergen levels and the specific IgE antibody to house dust mite have been reported.

OBJECTIVE

We studied the changes in IgG subclass antibodies to house dust mite associated with seasonal variation of house dust mite allergen levels in houses of mite-sensitive asthmatic patients.

METHODS

In 14 mite-sensitive asthmatic patients, house dust mite allergen (Der f 1) contents in bedding were measured monthly, and IgG subclass antibodies to house dust mite, Dermatophagoides farinae (D. farinae), were determined by enzyme-linked immunosorbent assay (ELISA) every 3 months from July to December.

RESULTS

The concentration of Der f 1 in dust from bedding reached maximum levels in August and September, and significantly decreased in November and December compared with August and September (P < .05). Levels of D. farinae-specific IgG4 antibodies significantly decreased in December compared with September (P < .05) with no statistically significant change between September and June (P > .05). Levels of D. farinae-specific IgG2 antibodies decreased significantly in December compared with June (P < .05). The levels of IgG1 and IgG3 antibodies to D. farinae showed no significant differences during the study period.

CONCLUSION

These findings suggest that seasonal changes in natural exposure to house dust mite allergen might lead to concurrent changes in specific IgG4 antibodies to house dust mite in mite-sensitive asthmatic patients and each IgG subclass antibodies to house dust mite might have a different kinetics.

Seasonal variation of skin reactivity and specific IgE antibody to house dust mite

BACKGROUND

House dust mite is an important cause of bronchial asthma worldwide. While the allergen is present all year-round, a seasonal variation of house dust mite allergen levels has been found. There have been few reports, however, on seasonal variation of specific immune response to house dust mite.

OBJECTIVE

We studied the changes in skin reactivity and specific IgE antibody to house dust mite associated with seasonal variation of house dust mite allergen levels in houses of mite-sensitive asthmatic patients.

METHODS

In 14 mite-sensitive asthmatic patients, house dust mite allergen (Der f 1) contents in bedding were measured monthly. Skin reactivity on prick test and specific IgE antibody to house dust mite, Dermatophagoides farinae (D. farinae), were determined every 3 months from july to December.

RESULTS

The concentration of Der f 1 in dust from bedding reached maximum levels in August and September, and significantly decreased in November and December compared with August and September (P < .05). Skin reactivity (a ratio of mean wheal diameter of allergen to histamine) to D. farinae decreased significantly in December compared with September (P < .05). Serum levels of total IgE and specific IgE antibody to D. farinae decreased significantly in December compared with September (P < .05).

CONCLUSION

These findings suggest that seasonal changes in natural exposure to house dust mite allergen might lead to concurrent changes in skin reactivity and specific IgE antibody to house dust mite in mite-sensitive asthmatic patients.