Evidence for two independent distributions of serum immunoglobulin E in atopic families: cognate and non-cognate IgE

Serum Periostin as a Biomarker for Predicting Clinical Response to House Dust Mite Sublingual Immunotherapy in Allergic Rhinitis

BACKGROUND

House dust mite (HDM) sublingual immunotherapy (SLIT) has proven to be effective for allergic rhinitis (AR), but its efficacy varies among patients. No candidate biomarkers for prediction of response to SLIT are available. Periostin, a matricellular protein, is involved in pathophysiology of AR, and its serum levels reflect airway allergic inflammation.

OBJECTIVE

To evaluate the relationship between serum periostin levels and current rhinitis control before and after standardized quality (SQ)-HDM SLIT, and to investigate the role of periostin in predicting clinical response.

METHODS

One hundred eleven subjects with HDM-induced AR were randomized to receive either SLIT plus pharmacotherapy or pharmacotherapy alone, for 48 weeks. At enrollment and the end of study, clinical characteristics and biomarkers that included serum periostin, serum HDM-specific IgE (s-IgE), total IgE, blood eosinophil counts, and Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ) were measured. The association between clinical indices or biomarkers and clinical response to SLIT was analyzed.

RESULTS

A response to SLIT was recorded in 64% (32 of 50) patients. High serum periostin levels (>30.2 ng/mL) were associated with an effective response to SLIT, and the magnitude of RQLQ improvement was correlated with the level of serum periostin. The sensitivity and specificity based on receiver operating characteristic analysis for periostin were higher than those of s-IgE. Multivariate regression analysis showed that serum periostin was an independent factor for SLIT responders.

CONCLUSIONS

Serum periostin appears to be a useful biomarker for predicting the response to SQ-HDM SLIT in patients with AR.

Mycosis Fungoides and Its Relationship to Atopy, Serum Total IgE, and Eosinophil Counts

INTRODUCTION

A recent serologic study and reports of increased serum total IgE (IgE-t) and eosinophil counts have suggested that the prevalence of atopy is more common in patients with mycosis fungoides (MF) than previously recognized.

PATIENTS AND METHODS

Patients with clinicopathologic features that were diagnostic and/or consistent with MF and/or the presence or absence of an atopic disorder (eg, allergic rhinitis, asthma, eczematous dermatitis), which was determined by patient history, eosinophil counts, and serum IgE-t obtained at evaluation, were selected from a patient registry. The MF population was divided into those with atypical and typical clinical presentations. We performed matching of controls using age, sex, and race from the 2005 to 2006 National Health Education Survey.

RESULTS

A history of allergic rhinitis was recorded for 186 of 728 patients (25.5%) with typical MF and 71 of 229 patients (31%) with atypical MF. However, the prevalence of asthma and eczema was low. The IgE-t and eosinophil counts were higher for patients with typical MF than for controls and for patients with atopic diathesis than for patients without atopy. The IgE-t and eosinophil counts were higher for the patients with advanced-stage MF compared with those for the patients with less-advanced disease for both atopic and nonatopic cohorts. In the Cox model with age and clinical stage as covariates, a history of atopy, increased IgE-t, and blood eosinophilia (> 500 cells/mm3) did not correlate with overall survival.

CONCLUSION

The findings from the present study did not reveal a significant association of atopy in patients with MF. However, atopy is a factor in the increased IgE-t and eosinophil counts observed in MF. Another factor is related to the disease stage, including possibly the influence of cytokines secreted by T-helper type 2-polarized neoplastic cells.

Sensitization to minor cat allergen components is associated with type-2 biomarkers in young asthmatics

BACKGROUND

Cat allergy is a major trigger of asthma world-wide. Molecular patterns of cat sensitization vary between individuals, but their relationship to inflammation in asthmatics has not been extensively studied.

OBJECTIVE

To investigate the prevalence and levels of IgE antibodies against different cat allergen components and their relationship to type-2 inflammation and total IgE among young asthmatic subjects sensitized to furry animals.

METHODS

Patients with asthma (age 10-35 years; n = 266) and IgE sensitization to cat, dog or horse extract (ImmunoCAP), were analysed for IgE to the cat allergen components Fel d 1 (secretoglobin), Fel d 2 (serum albumin), Fel d 4 and Fel d 7 (lipocalins). Independent associations between IgE-antibody concentrations, and fraction of exhaled nitric oxide (FeNO), blood eosinophil (B-Eos) count, and total IgE were analysed by multiple linear regression after adjustment for possible confounders.

RESULTS

The level of IgE against Fel d 2 was independently related to FeNO (P = .012) and total IgE (P < .001), and IgE against Fel d 4 associated with Β-Eos count (P = .009) and total IgE (P < .001). IgE antibodies against Fel d 1 or cat extract did not independently relate to these inflammatory markers (P = .23-.51).

CONCLUSIONS

Levels of IgE to lipocalin (Fel d 4) and serum albumin (Fel d 2), but not to secretoglobin (Fel d 1) or cat extract, were independently associated with type-2 biomarkers and total IgE in young asthmatics.

CLINICAL RELEVANCE

We suggest that measurement of IgE to minor cat allergen components may be useful when investigating asthma morbidity in cat allergic subjects.

The absence of serum IgE antibodies indicates non-type 2 disease in young asthmatics

BACKGROUND

Atopic asthma is associated with elevated type-2 biomarkers such as fraction of exhaled nitric oxide (FeNO) and blood eosinophil (B-Eos) count. However, increased type 2 markers have also been reported in traditionally defined non-atopic asthma.

OBJECTIVE

To determine a clinically useful level of IgE sensitization for ruling out type 2 asthma.

METHODS

Asthmatics (N = 408; age 10-35 years) were analysed using the multi-allergen tests Phadiatop and fx5 (ImmunoCAP). Subjects were grouped based on IgE-antibody concentrations: ≥0.35 kU_A /L for at least one test (n = 326) or <0.35 kU_A /L for both tests (n = 82). Τhe latter group was subsequently divided into 2 groups: IgE 0.10-0.34 kU_A /L (n = 34) and IgE < 0.10 kU_A /L (n = 48). The relationships between type 2 biomarkers, and inadequate asthma control (ACT < 20), reduced lung function (FEV₁  < 80%), recent asthma attacks and airway hyperresponsiveness (AHR) to methacholine were determined.

RESULTS

In univariate analyses, at least one type 2 marker related to each asthma outcome in subjects with IgE ≥0.35 kU_A /L. In subjects with IgE 0.10-0.34 kU_A /L, elevated FeNO related to reduced lung function (P = .008) and B-Eos to AHR (P = .03). No associations were found in subjects with IgE < 0.10 kU_A /L. In multivariate analysis, a relationship between FeNO and reduced lung function remained in subjects with IgE < 0.35 kU_A /L (P = .03).

CONCLUSION AND CLINICAL RELEVANCE

Clinically relevant elevation of type 2 biomarkers was seen in young asthmatics with IgE antibodies <0.35 kU_A /L, but not those with IgE < 0.10 kU_A /L. It seems possible to define non-type 2 asthma through sensitive IgE-antibody measurement.

High serum β-lactams specific/total IgE ratio is associated with immediate reactions to β-lactams antibiotics

Total serum IgE result from the combination of specific and non-specific pools. High specific/total IgE ratio may reflect high level of allergen-specific IgE on mast cells. No data regarding its applications to drug allergies is available. One hundred seventy-one patients with a history of immediate reactions to β-lactams, confirmed by positive skin testing, and 122 control subjects tolerant to β-lactams, were studied. CAP System was used for the detection of serum total and specific IgE antibodies. The specific/total IgE ratio was tested for diagnostic accuracy compared with conventional criteria. We finally performed a simulation study to expand our investigation of the performance of the specific/total IgE ratio index in a scenario in which the new CAP detection threshold is lowered further. Specific/total IgE ratio values ≥0.002 were observed more frequently in reactive than in controls. Seventy-four of 80 subjects with values ≥0.002 were allergic to β-lactams, yielding a positive predictive value of 92.5%. The application of specific/total IgE ratio significantly improves the positive likelihood ratio and the overall diagnostic performance. In addition, we showed the capability of this new criterion to identify true reactive patients even among subjects with high levels of total IgE (>200 kU/L). Significant increase in both receiver operator characteristic (ROC) curve and sensitivity were observed in imputed case of the simulation study. The β-lactams-specific/total IgE ratio may be an additional index compared to the common criterion of positivity to a single hapten in the allergological work-up of patients with β-lactams immediate adverse reactions.

Natural history of perceived food hypersensitivity and IgE sensitisation to food allergens in a cohort of adults

Background

No longitudinal studies exist on the natural history of food hypersensitivity and IgE sensitisation to food allergens in adults.

Objective

To examine the natural history of food hypersensitivity, the natural history of IgE sensitisation to food allergens and to investigate the risk factors for new onset food hypersensitivity.

Methods

Food hypersensitivity was questionnaire-assessed in 2307 individuals (aged 20–45 years) from Iceland and Sweden during the European Community Respiratory Health Survey both at baseline and follow-up 9 years later. IgE food and aeroallergen sensitisation were assessed in a subgroup of these individuals (n = 807). Values of 0.35 kU/L and above were regarded as positive sensitisation.

Results

Food hypersensitivity was reported by 21% of the subjects and this proportion remained unchanged at follow-up (p = 0.58). Fruits, nuts and vegetables were the three most common causes of food hypersensitivity, with a similar prevalence at baseline and follow-up. The prevalence IgE sensitisation to food allergens decreased in general by 56% (p<0.001) and IgE sensitisation to peanut decreased in particular by 67% (p = 0.003). The prevalence of timothy grass IgE sensitisation decreased by 15% (p = 0.003) while cat, mite and birch IgE sensitisation did not decrease significantly. Female sex, rhinitis, eczema and presence of IgE sensitisation to aeroallergens were independently associated with new onset food hypersensitivity.

Conclusion

The prevalence of food hypersensitivity remained unchanged while the prevalence of IgE sensitisation to food allergens decreased in adults over a 9-year follow-up period. The decrease in prevalence of IgE sensitisation to food allergens was considerably larger than the change in prevalence of IgE sensitisation to aeroallergens.

A peroxidase-active aptazyme as an isothermally amplifiable label in an aptazyme-linked oligonucleotide assay for low-picomolar IgE detection

A peroxidase-active hemin-aptamer was clicked onto an immunoglobulin E (IgE) binding aptamer. The resulting bifunctional aptamer was successfully used in a highly sensitive aptazyme-linked oligonucleotide assay (ALONA) for the detection of IgE. The sensitivity of the assay is enhanced by isothermal amplification of the aptazyme followed by colorimetric detection of the aptazyme's peroxidase activity, which can easily be evaluated even without advanced lab instruments.

Serum total immunoglobulin E is a surrogate of atopy in adult-onset asthma: a longitudinal study

BACKGROUND

Studies have shown that serum total immunoglobulin E (IgE) levels are higher in asthmatics. However, the role of the serum total IgE level, independently from atopy, in adult asthma is not understood. We studied the associations between serum total IgE, the number of sensitizations and the sum of specific IgEs and new-onset asthma using longitudinal data from the European Community Respiratory Health Survey.

METHODS

Serum total and specific IgE to 4 common inhalant allergens were measured at baseline in 9,175 participants, with a follow-up of 9 years. Individuals with asthma history and/or asthma symptoms were excluded. Atopy was defined as the presence of at least one specific IgE ≥0.35 kU/l. Total and specific IgEs were regressed against new-onset asthma using multivariate logistic regression with a random intercept for the study centre.

RESULTS

Two hundred and ninety-seven participants had developed asthma during follow-up (incidence rate 5.7 per 1,000 person-years). A 10% higher level of total IgE was associated with a 12% increased risk of new-onset asthma (p = 0.005). However, after adjustment for the number of positive specific IgEs [odds ratio (OR) for multiple sensitization 1.74, 95% confidence interval (CI) 1.05–2.88] and the sum of allergenspecific IgEs (OR 1.18, 95% CI 1.00–1.40), the association between total IgE and asthma disappeared (OR 1.00, 95% CI 0.91–1.10). Seventeen percent of new-onset asthma cases could be attributed to atopy, and this estimate was not largely modified when the total IgE level was simultaneously taken into account.

CONCLUSIONS

After taking into account the number and intensity of 4 specific IgEs, the serum total IgE level was not associated with new-onset asthma in adults.

Relation between objective measures of atopy and myocardial infarction in the United States

BACKGROUND

Although rodent studies indicate that atherosclerosis is a T(H)1-mediated disease and that atopic T(H)2 immunity is atheroprotective, findings in humans are conflicting. Total IgE (tIgE) is associated with atherosclerotic disease but has limited specificity for atopy.

OBJECTIVE

Our aim was to determine the relation between atopy, as indicated by a broad panel of serum allergen-specific IgE (sIgE), and past myocardial infarction (MI) in a sample representative of the US population.

METHODS

Data were analyzed from 4002 participants aged ≥ 20 years from the 2005-2006 National Health and Nutrition Examination Survey.

RESULTS

Subjects reporting a history of MI had lower summed sIgE (5.51 vs 7.71 kU/L; P < .001) and were less likely to have ≥ 1 positive sIgE test (29.9% vs 44.6%; P = .02) or current hay fever (3.3% vs 7.6%; P = .002). After adjustment for age, sex, race/ethnicity, diabetes mellitus, hypertension, family history of MI, smoking, total/high-density lipoprotein cholesterol, body mass index, and C-reactive protein, the odds ratio (OR) for MI was 0.91 (95% CI, 0.85-0.97) per positive sIgE; 0.70 (95% CI, 0.57-0.85) per 2-fold increase in sum[sIgE]; and 0.82 (95% CI, 0.69-0.98) per 10% increase in the ratio of sum[sIgE] to tIgE. Analysis with 7 data-driven, prespecified allergen clusters found that house dust mite is the only allergen cluster for which sIgE is associated with reduced odds for MI (fully adjusted OR, 0.36; 95% CI, 0.20-0.64).

CONCLUSION

Serum sIgE is inversely related to MI in the US population in a manner independent of multiple coronary risk factors.

Familial aggregation of allergen-specific sensitization and asthma

BACKGROUND

Familial aggregation of specific response to allergens and asthma adjusted for age and sensitization to multiple allergens was assessed in two large population cohorts.

METHODS

Allergen skin prick tests (SPTs) were administered to 1151 families in the Tucson Children's Respiratory Study (CRS) and 435 families in the Tucson Epidemiological Study of Airway Obstructive Disease (TESAOD). Sensitization was defined by wheal size ≥3 mm; physician-diagnosed asthma at age ≥8 yr was based on questionnaires. Using S.A.G.E. 6.1 software ASSOC and FCOR, familial correlations of crude and adjusted phenotypes were evaluated.

RESULTS

Crude estimates of parent-offspring (P-O) and sibling correlations were statistically significant for most allergens, ranging from 0.03 to 0.29. After adjusting for age of assessment and 'other atopy' (SPT-positive response to additional allergens), correlations were reduced by 14-71%. Sibling correlations for specific response to allergens were consistently higher than P-O correlations, but this difference was significant only for dust mite and weed mix in the TESAOD population. Familial correlation for atopic status (any positive SPTs vs. none) tended to be higher than for specific allergens. Asthma, with and without adjustment, showed greater familial correlation than either specific or general SPT response and significantly higher sibling correlation in TESAOD than in CRS, probably due to the older age of the siblings and the longer period of ascertainment.

CONCLUSIONS

Significant familial aggregation of specific response to allergen after adjustment for other atopy appears to reflect a genetic propensity toward atopy, dependent on shared familial exposures. Results also suggest that inheritance of asthma is independent of atopic sensitization.

Nanocrystalline diamond impedimetric aptasensor for the label-free detection of human IgE

Like antibodies, aptamers are highly valuable as bioreceptor molecules for protein biomarkers because of their excellent selectivity, specificity and stability. The integration of aptamers with semiconducting materials offers great potential for the development of reliable aptasensors. In this paper we present an aptamer-based impedimetric biosensor using a nanocrystalline diamond (NCD) film as a working electrode for the direct and label-free detection of human immunoglobulin E (IgE). Amino (NH(2))-terminated IgE aptamers were covalently attached to carboxyl (COOH)-modified NCD surfaces using carbodiimide chemistry. Electrochemical impedance spectroscopy (EIS) was applied to measure the changes in interfacial electrical properties that arise when the aptamer-functionalized diamond surface was exposed to IgE solutions. During incubation, the formation of aptamer-IgE complexes caused a significant change in the capacitance of the double-layer, in good correspondence with the IgE concentration. The linear dynamic range of IgE detection was from 0.03 μg/mL to 42.8 μg/mL. The detection limit of the aptasensor reached physiologically relevant concentrations (0.03 μg/mL). The NCD-based aptasensor was demonstrated to be highly selective even in the presence of a large excess of IgG. In addition, the aptasensor provided reproducible signals during six regeneration cycles. The impedimetric aptasensor was successfully tested on human serum samples, which opens up the potential of using EIS for direct and label-free detection of IgE levels in blood serum.

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

BACKGROUND

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.

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Total serum IgE levels are associated with ambient ozone concentration in asthmatic adults

BACKGROUND

Effects of air pollution exposure on IgE-mediated response in asthmatics are poorly investigated. The aim was to examine the relationship between air pollution concentrations and total IgE levels in adult asthmatics.

METHODS

The present study relates to the 369 asthmatic adults from the French Epidemiological study on Genetics and Environment of Asthma (EGEA), with availability of data on both total serum IgE measurements and air pollution concentrations. Geo-statistical models were performed on 4 x 4 km grids to assess individual outdoor air pollution exposure. Annual outdoor concentrations of ozone (O(3)), nitrogen dioxide (NO(2)), sulphur dioxide (SO(2)), and particulate matter smaller than 10 microm size (PM(10)), and concentrations of summer ozone were assigned to subject's home address.

RESULTS

The geometric mean of total IgE was 161 IU/ml and the average of O(3) exposure was 44.9 +/- 9.5 microg/m(3). Ozone concentrations were positively related to total IgE levels and an increase of 10 microg/m(3) of O(3) resulted in an increase of 20.4% (95% CI = 3.0-40.7) in total IgE levels. Adjustment for age, gender, smoking habits and previous life in the countryside did not change the results, and an increase of 19.1% (2.4-38.6) in total IgE was observed with O(3). Negative associations observed between NO(2) and total IgE levels disappeared after including O(3) in the models. Neither SO(2) nor PM(10) were correlated with total IgE levels.

CONCLUSIONS

Results suggest that O(3) or related ambient pollutants may up-regulate total IgE levels among asthmatic adults.

Search for quantitative trait loci of atopy-associated immune responses using allergen-specific IgG1 as an "endophenotype"

Inherited atopic diseases of humans arise from adverse adaptive humoral responses to noninfectious environmental allergens. We previously reported that allergen-specific IgG1 provides more reliable heritability estimates for responses to allergens than total IgE. Genome scans were done for 91 Caucasian nuclear families with history of atopy for total IgE and IgG1 produced against a common major allergen from house dust mite, Der p 1. Suggestive associations for Der p 1-IgG1 production were found at 7 quantitative trait loci (QTL) (logarithm of the odds, LOD > or = 1.23; p < or = 0.009) with QTL-specific heritabilities of 73%-80%. Scans using total IgE found suggestive associations for 12 QTLs (LOD > or = 1.44; p < or = 0.004), but QTL-specific heritabilities only in the range of 30%-35%. Allergen-specific IgG1 is a suitable "endophenotype" to be used in searches for genes associated with atopy-associated humoral immune responses to common aeroallergens.

The relevance of microbial allergens to the IgE antibody repertoire in atopic and nonatopic eczema

BACKGROUND

A propensity to microbial skin infections has been reported in atopic ("high IgE") and nonatopic ("low IgE") forms of eczema. However, the relationship between antimicrobial IgE antibodies and nonatopic disease is unclear.

OBJECTIVE

We examined the relevance of microbial allergens to the allergen-specific IgE antibody repertoire in patients with atopic dermatitis.

METHODS

Patients with IgE levels of less than 150 IU/mL were stratified according to sensitivity (n = 22) or no sensitivity (n = 27) to 11 common food allergens and aeroallergens. The prevalence and titers of antimicrobial IgE antibodies were compared with those of patients (n = 36) with increased total IgE levels (>150 IU/mL). Skin-derived serum chemokines were also analyzed.

RESULTS

Patients with low IgE levels showed decreased disease severity, increased age of onset, a striking female predominance, and a distinct distribution of skin lesions. High titer IgE antibodies (sum of 8 bacterial and fungal allergens = 29.8 +/- 32.6 IU/mL) and multisensitization specific for microbial allergens was characteristic of patients with high IgE levels, with an overall 84% positivity; however, antimicrobial IgE antibodies comprised 3% or less of allergen-specific IgE antibodies. By contrast, antimicrobial IgE antibodies were detected in only 20% of patients with low IgE, and titers were negligible, irrespective of sensitization to common allergens. These patients were monosensitized, and exclusive microbial sensitivity was uncommon (10%). Patients with low IgE with no sensitivity to common allergens had lower levels of serum macrophage inflammatory protein 3alpha compared with their sensitized counterparts.

CONCLUSION

Antimicrobial IgE antibodies are uncommon in patients with atopic dermatitis with low IgE levels.

CLINICAL IMPLICATIONS

Hypersensitivity to microbial allergens is an unlikely trigger for eczematous eruptions in patients with low IgE levels.

Contribution of dust mite and cat specific IgE to total IgE: relevance to asthma prevalence

BACKGROUND

The prevalence of asthma is strikingly different in some Westernized countries: approximately 20% in New Zealand and approximately 8% in northern Sweden.

OBJECTIVE

We investigated differences in total IgE and in the prevalence of wheezing related to the observation that high exposure to dust mite allergens induces high titers of IgE antibodies.

METHODS

Two age-matched, population-based cohorts-1155 children in New Zealand (224 sera) and 3431 children (797 sera) in the Norrbotten area of Sweden-were studied. Sera were assayed for total IgE and specific IgE antibodies to relevant allergens.

RESULTS

The mean total IgE among wheezing children was higher in New Zealand than Sweden (218 IU/mL vs 65.2 IU/mL; P < .001). In addition, the prevalence of high titer specific IgE antibody (> or =50 IU/mL) was greater among the wheezing children in New Zealand compared with Sweden (35.7% vs 13.0%; P < .001). Specific IgE antibody to mite in New Zealand was significantly related to high total IgE (> or =200 IU/mL; r = 0.47; P < .001), whereas the IgE antibody response to cat allergens did not make a significant contribution to high total IgE in either country.

CONCLUSION

The quantity of IgE antibody produced to dust mite provides a possible explanation for the higher total IgE levels found in children in New Zealand and may help to explain the differences in prevalence and severity of asthma between these 2 countries.

CLINICAL IMPLICATIONS

Specific IgE antibody responses to dust mite and cat allergens may contribute differently to total serum IgE and to the prevalence of allergic disease.

Random allergen-specific IgE expression in atopic families: evidence for inherited "stochastic bias" in adverse immune response development to non-infectious antigens

The complex inherited human atopic diseases are associated with adverse IgE-mediated immune responses, notably allergen-specific IgE that presumably involves the input from one or more genes. However, gene searches have met with limited success, possibly because a causally direct gene input-trait outcome assumption is not valid for these immune responses. To test this assumption, we determined the probability distributions of quantitative IgE responses associated with atopy, and used these to determine the statistical interdependence among first-degree relatives (parent-child and sibling-sibling) from families with history of atopic asthma (total available N=1099). Each person was screened for asthma history, pulmonary responses by spirometry and atopic immune responses using serum total IgE and skin prick tests (SPT) to 14 allergens. Heritability estimates were made by variance components analysis for quantitative IgE traits. The serum total IgE distribution comprised statistically independent sub-sets when individuals were categorized as either SPT [-] or SPT [+], reflecting contributions from non-pathology associated basal IgE and pathology-associated allergen-specific IgE. However, heritability estimates were significant only for basal IgE, while total allergen-specific IgE production was a random variable independent of inheritance. Genes for specific IgE-mediated responses are not obligately inherited. Rather, gene products that modulate underlying stimulus-response coupling interactions and alter the probabilities influencing adverse immune responses are inherited, but an individual's specific pathologic outcome is a random variable. These results support a model of "stochastic bias" that "skews" an immune response to non-infectious antigens among people with an inherited predisposition for atopy.

Allergen-specific IgG1 provides parsimonious heritability estimates for atopy-associated immune responses to allergens

Although serum total immunoglobulin E (IgE) is generally elevated in atopic conditions, it is an unreliable trait for dissecting the genetic and environmental components contributing to atopic immune responses, because it can be significantly confounded by demographic factors (age, gender, and race) and clinical status (atopic vs nonatopic). Allergen-specific IgE is a discontinuous trait present only in those with sensitivity to allergens. However, all people will produce allergen-specific immunoglobulin G1 (IgG1), which is elevated among those atopically sensitized to specific allergens. We screened 91 Caucasian nuclear families (N = 367) with medical histories of atopic diseases and used variance components analysis to compare heritability estimates for total IgE and IgG1 produced against the common major allergen from house dust mite Dermatophagoides pteronyssinus (Der p 1). An estimate of total IgE heritability was about 48%, although this was significantly confounded by age, gender, and clinical atopic status. In contrast, Der p 1-IgG1 demonstrated a significant inherited component of about 62% that was not influenced by age, gender, or clinical status. For genetic studies of atopic humoral responses, allergen-specific IgG1 may be a more reliable quantitative trait than serum IgE. Moreover, atopy is an inherited deregulation of immune responses to noninfectious antigens, involving antibody isotypes other than IgE.

CD14 promoter polymorphisms in atopic families: implications for modulated allergen-specific immunoglobulin E and G1 responses

BACKGROUND

CD14 promoter DNA sequence polymorphisms for the endotoxin receptor gene have been implicated in modulating allergen-specific immunoglobulin (Ig)E responses in randomly selected individuals with atopy. We sought to determine if a single nucleotide polymorphism in the CD14 promoter region is associated with atopy in atopic families, and to assess its influence on serum levels of CD14 and allergen-specific IgE and IgG1 responses.

METHODS

We screened 367 members of 91 Caucasian nuclear families with a history of asthma for pulmonary function by spirometry, including methacholine challenge to detect bronchial hyperreactivity, and atopy by serum total IgE and skin prick test to 14 allergens. The CD14 promoter single nucleotide polymorphism was analyzed in DNA isolated from peripheral blood mononuclear cells to identify C/C, C/T and T/T genotypes. Serum tests were done for soluble CD14 (sCD14) and dust mite-specific antibody (Der p 1-IgG1).

RESULTS

Serum sCD14 levels were not associated with clinical phenotypes (asthma, bronchial hyperreactivity or atopy). However, sCD14 levels were inversely related to both allergen-specific IgE and Der p 1-IgG1 production, but only among those with evidence of atopic sensitization. Linear regression analysis, accounting for random family effects, demonstrated a higher production of allergen-specific IgE or Der p 1-IgG1 associated with the T/T genotype and a lower level of specific IgE and IgG1 production associated with sCD14 levels.

CONCLUSIONS

An element of the innate immune system (CD14) has profound effects upon modulating the acquired allergen-specific immunoglobulin responses among those with an inherited atopic predisposition.

Nickel Elicits Concomitant and Correlated in vitro Production of Th1-, Th2-Type and Regulatory Cytokines in Subjects with Contact Allergy to Nickel

Nickel (Ni2+) elicits production of functionally distinct cytokines in vitro, but the relation between the cytokine profile and the degree of the allergic reaction in vivo needs to be better defined in order to improve the understanding of the immunological mechanisms involved in contact allergy and to facilitate development of in vitro diagnostics. The aim of the study was to define Th1-type [interferon-gamma (IFN-gamma)], Th2-type [interleukin-4 (IL-4), IL-5 and IL-13] and regulatory (IL-10) cytokine responses to Ni2+ in peripheral blood mononuclear cells (PBMC) from subjects with varying patch test reactivity to Ni2+. The study included subjects with strong (+3), moderate (+2), weak (+1) or negative (controls) patch test reactivity to Ni2+ (n = 10 per group). All +3 and +2 subjects but only three +1 subjects had a clinical history of contact allergy to Ni(2+). Cytokine production of PBMC stimulated with Ni(2+) was determined by enzyme-linked immunospot and/or enzyme-linked immunosorbent assay. Ni2+ elicited significant production of all cytokines in PBMC from patch-test-positive subjects versus controls with a positive correlation between each cytokine and the patch test reactivity as well as with other cytokines. More subjects responded to Ni2+ above cut-off values with Th2-type cytokines as compared with IFN-gamma or IL-10; 100% of +3, 80% of +2, 50% of +1 and 0% of control subjects displayed reactivity to Ni2+ based on IL-4 and IL-13 assays. Despite the prevailing view of Ni2+ allergy as a type-1-mediated condition, the in vivo reactivity to Ni2+ correlated with a mixed Th1-type, Th2-type and regulatory cytokine response to Ni2+in vitro. The results accentuate the importance of type 2 responses in contact allergy and also demonstrate that IL-4 and IL-13 are reliable markers for Ni2+ allergy.

Targeting immunoglobulin E as a novel treatment for asthma

Omalizumab is a recently developed monoclonal anti-IgE antibody. Clinical trials have demonstrated its efficacy in patients with moderate-to-severe and severe or poorly controlled allergic asthma, in patients with seasonal and perennial allergic disease, and in subjects with concomitant asthma and allergic rhinitis. Patients with more severe asthma appear to obtain the greatest benefit from omalizumab therapy. Omalizumab is well tolerated and has a good safety profile. Anti-inflammatory activity has been shown in both allergic asthma and allergic rhinitis. These results confirm the importance of IgE in allergic disease and support the rationale behind the development of a therapeutic anti-IgE antibody. Omalizumab is a significant addition to current asthma treatments and shows great promise as a therapy for allergic rhinitis, in particular for those patients with concomitant allergic disease.