Relation between IgG antibodies to foods and IgE antibodies to milk, egg, cat, dog and/or mite in a cross-sectional study

The clinical significance of allergen-specific IgG4 in allergic diseases

IgG4 is a subclass of IgG antibody with a unique molecular feature of (Fragment antigen- binding) Fab-arm exchange, allowing bispecific antigen binding in a mono-valent manner. With low binding affinity to C1q and Fcγreceptors, IgG4 is incapable of forming immune complexes and activating the complement pathway, exhibiting a non-inflammatory feature. IgG4 is produced similarly to IgE and is considered a modified reaction to IgE class-switching response under certain conditions. It could also counteract IgE-activated inflammation. However, the clinical significance of IgG4 in allergic diseases is complex and controversial. Three viewpoints have been suggested to describe the role of IgG4. IgG4 can act as a tolerance-inducer to play a protective role under repeated and rapid incremental dosing of allergen exposure in allergen immunotherapy (AIT), supported by allergies in cat raisers and venom desensitization in beekeepers. Another viewpoint accepted by mainstream specialists and guidelines of Food Allergy and Management in different countries points out that food-specific IgG4 is a bystander in food allergy and should not be used as a diagnostic tool in clinical work. However, eosinophilic esophagitis (EoE) investigation revealed a direct clinical relevance between physiopathology and serum IgG4 in cow milk and wheat. These factors indicate that allergen-specific IgG4 plays a multifaceted role in allergic diseases that is protective or pathogenic depending on different allergens or exposure conditions.

Evolution of the IgE and IgG repertoire to a comprehensive array of allergen molecules in the first decade of life

BACKGROUND

In early childhood, the allergen-specific IgG repertoire is mainly directed to animal and vegetable food molecules and infrequently to airborne molecules. It is unknown whether this early pattern is maintained throughout childhood.

OBJECTIVE

To investigate the evolution of IgG and IgE responses to a broad panel of allergenic molecules from birth to age 10 years.

METHODS

We examined the sera collected between birth and age 10 years from participants in the German Multicentre Allergy Study, a birth cohort born in 1990. The IgE (cutoff ≥0.30 ISU) and IgG (cutoff ≥0.10 ISU) responses to 35 genuine allergenic molecules were measured with a multiplex microarray approach (ImmunoCAP ISAC™).

RESULTS

IgE responses were mostly directed against a restricted group of airborne molecules, with a sequence and prevalence hierarchy (Phl p 1> Bet v 1> Fel d 1> Phl p 5> Der p 2> Der p 1) largely maintained over time. Conversely, the IgG repertoire was much broader, starting with animal foodborne, then spreading to vegetable foodborne and finally to airborne molecules. A strong and persistent IgG response to a given airborne molecule almost invariably preceded or accompanied an IgE response to that molecule.

CONCLUSIONS

The evolution of IgG and IgE responses throughout childhood differs widely at population level. IgG responses are mostly directed to animal food allergens, while IgE responses are dominated by airborne allergens. However, a strong IgG response almost invariably precedes or accompanies the appearance of IgE to the same molecule in specifically sensitized subjects.

Prebiotic-supplemented partially hydrolysed cow's milk formula for the prevention of eczema in high-risk infants: a randomized controlled trial

Background

Prevention guidelines for infants at high risk of allergic disease recommend hydrolysed formula if formula is introduced before 6 months, but evidence is mixed. Adding specific oligosaccharides may improve outcomes.

Objective

To evaluate whether partially hydrolysed whey formula containing oligosaccharides (0.8 g/100 ml) (pHF‐OS) can prevent eczema in high‐risk infants [ISRCTN65195597].

Methods

We conducted a parallel‐group, multicentre, randomized double‐blind controlled trial of pHF‐OS vs standard cow's milk formula. Infants with a family history of allergic disease were randomized (stratified by centre/maternal allergy) to active (n = 432) or control (n = 431) formula until 6 months of age if formula was introduced before 18 weeks. Primary outcome was cumulative incidence of eczema by 12 months in infants randomized at 0–4 weeks (375 pHF‐OS, 383 control). Secondary outcomes were cumulative incidence of eczema by 12 or 18 months in all infants randomized, immune markers at 6 months and adverse events.

Results

Eczema occurred by 12 months in 84/293 (28.7%) infants allocated to pHF‐OS at 0‐4 weeks of age, vs 93/324 (28.7%) control (OR 0.98 95% CI 0.68, 1.40; P = 0.90), and 107/347 (30.8%) pHF‐OS vs 112/370 (30.3%) control in all infants randomized (OR 0.99 95% CI 0.71, 1.37; P = 0.94). pHF‐OS did not change most immune markers including total/specific IgE; however, pHF‐OS reduced cow's milk‐specific IgG1 (P < 0.0001) and increased regulatory T‐cell and plasmacytoid dendritic cell percentages. There was no group difference in adverse events.

Conclusion

pHF‐OS does not prevent eczema in the first year in high‐risk infants. The immunological changes found require confirmation in a separate cohort.

Differential immuno-kinetic assays of allergen-specific binding for peanut allergy serum analysis

A label-free nanoparticle array platform has been used to detect total peanut allergen-specific binding from whole serum of patients suffering from peanut allergy. The serum from 10 patients was screened against a four-allergen panel of cat and dog dander, dust mite and peanut allergen protein Ara h1. The IgE and IgG contributions to the total specific-binding protein load to Ara h1 were identified using two secondary IgG- and IgE-specific antibodies and were found to contribute less than 50 % of the total specific protein load. The total mass of IgE, IgE and the unresolved specific-binding protein ΔsBP for Ara h1 provides a new serum profile for high-RAST-grade patients 5 and 6 with the IgG/IgE ratio of 4 ± 2 and ΔsBP/IgE ratio of 17 ± 11, neither of which is protective for the small patient cohort.

Peanut sensitization during the first 5 yr of life is associated with elevated levels of peanut-specific IgG

BACKGROUND

  Allergen-specific IgE antibodies are implicated in allergic diseases while allergen-specific IgG antibodies have been proposed to prevent allergic reactions. The objective for this study was to study whether the immune response (IgG and IgG4) to peanut differs in IgE-sensitized and non-sensitized young children.

METHODS

  A total of 239 children have been followed prospectively from birth to 5 yr of age. The levels of IgG and IgG4 to peanut, Ara h 2, and Ara h 8 were analyzed at 2 and 5 yr of age and related to IgE sensitization and peanut consumption.

RESULTS

  The levels of peanut-specific IgG and IgG4 were significantly higher in peanut-sensitized children at 2 and 5 yr of age when compared with non-sensitized children and children sensitized to other food/inhalant allergens. A strong correlation was seen between levels of peanut-specific IgG/IgG4-ratios and peanut-specific IgE at 5 yr of age. Children avoiding peanuts, a subgroup of the peanut sensitized, had statistically significant higher levels of IgE to peanut and a tendency of higher IgG and IgG4 levels to peanut. In the avoidance group, significant correlations between IgE and IgG/IgG4 to peanut were found compared with children eating peanuts.

CONCLUSION

  Peanut-specific IgG or IgG4 levels were elevated in peanut-sensitized children especially those avoiding peanuts. In our study, IgG and IgG4 do not seem to indicate tolerance or protection from sensitization.

Intrauterine sensitization of allergen-specific IgE analyzed by a highly sensitive new allergen microarray

BACKGROUND

To design a rational allergy prevention program, it is important to determine whether allergic sensitization starts in utero under the maternal immune system.

OBJECTIVE

To investigate the origin of allergen-specific IgE antibodies in cord blood (CB) and maternofetal transfer of immunoglobulins.

METHODS

The levels of food and inhalant allergen-specific IgE, IgA, IgG, and IgG(4) antibodies in CB and maternal blood (MB) from 92 paired neonates and mothers were measured by using a novel allergen microarray of diamond-like-carbon-coated chip, with high-sensitivity detection of allergen-specific antibodies and allergen profiles.

RESULTS

The levels of allergen-specific IgE antibodies against food and inhalant allergens and allergen profiles were identical in CB and newborn blood, but the levels and profiles, specifically against inhalant allergens, were different from those in MB. The level of allergen-specific IgA antibodies was below the detection levels in CB despite clear detection in MB. Therefore, contamination with MB in CB was excluded on the basis of extremely low levels of IgA antibodies in CB and the obvious mismatch of the allergen-specific IgE and IgA profiles between CB and MB. However, the levels of allergen-specific IgG and IgG(4) antibodies and their allergen profiles were almost identical in both MB and CB.

CONCLUSION

Allergen-specific levels of IgE and IgA antibodies and their allergen profiles analyzed by the diamond-like-carbon allergen chip indicate that IgE antibodies in CB are of fetal origin. Food-allergen specific IgE antibodies were detected more often than inhalant-allergen specific IgE antibodies in CB, the reason of which remains unclarified.

Useful biomarkers in pediatric eosinophilic duodenitis and their existence: a case-control, single-blind, observational pilot study

OBJECTIVES

The aim of this study was to determine whether screening for food hypersensitivity could be a clinically useful biomarker for eosinophilic duodenitis in the pediatric population.

PATIENTS AND METHODS

Twenty-two patients with functional dyspepsia and 19 controls with no significant history of gastrointestinal or allergic disorders were enrolled. Participants underwent skin prick, atopy patch, and serum-specific (S)-IgE, -IgG, and -IgG4 testing to corn, wheat, soy, peanut, milk, and egg. Participants in the patient group also underwent endoscopy with biopsies as part of standard care.

RESULTS

Three participants in the patient group did not exhibit duodenal eosinophilia on biopsy and were excluded from data analyses. The patient group consisted of 13 females and 6 males, 8 to 17 years of age. The control group consisted of 10 females and 9 males, 8 to 17 years of age. Seven patients had at least 1 positive reaction to food by skin prick, atopy patch, or SIgE testing compared with 7 controls; odds ratio 1; 95% confidence interval 0.3 to 3.7. Receiver operating characteristics curves showed SIgG and SIgG4 performed poorly or no better than chance for predicting group assignment.

CONCLUSIONS

Allergy screening for the foods tested was not useful as a biomarker for eosinophilic duodenitis in this small study. A higher rate of positive reactions to patch testing was observed in the control group than previous studies have reported. The incidence of a positive food patch test in nonselected subjects needs further investigation. Method standardization and establishment of reference intervals are needed for atopy patch tests, SIgG, and SIgG4 to better evaluate the clinical value of these measures.

Testing for IgG4 against foods is not recommended as a diagnostic tool: EAACI Task Force Report

Serological tests for immunoglobulin G4 (IgG4) against foods are persistently promoted for the diagnosis of food-induced hypersensitivity. Since many patients believe that their symptoms are related to food ingestion without diagnostic confirmation of a causal relationship, tests for food-specific IgG4 represent a growing market. Testing for blood IgG4 against different foods is performed with large-scale screening for hundreds of food items by enzyme-linked immunosorbent assay-type and radioallergosorbent-type assays in young children, adolescents and adults. However, many serum samples show positive IgG4 results without corresponding clinical symptoms. These findings, combined with the lack of convincing evidence for histamine-releasing properties of IgG4 in humans, and lack of any controlled studies on the diagnostic value of IgG4 testing in food allergy, do not provide any basis for the hypothesis that food-specific IgG4 should be attributed with an effector role in food hypersensitivity. In contrast to the disputed beliefs, IgG4 against foods indicates that the organism has been repeatedly exposed to food components, recognized as foreign proteins by the immune system. Its presence should not be considered as a factor which induces hypersensitivity, but rather as an indicator for immunological tolerance, linked to the activity of regulatory T cells. In conclusion, food-specific IgG4 does not indicate (imminent) food allergy or intolerance, but rather a physiological response of the immune system after exposition to food components. Therefore, testing of IgG4 to foods is considered as irrelevant for the laboratory work-up of food allergy or intolerance and should not be performed in case of food-related complaints.

Ovalbumin-specific immunoglobulin G and subclass responses through the first 5 years of life in relation to duration of egg sensitization and the development of asthma

BACKGROUND

Egg sensitization, particularly persistent sensitization, is a risk factor for later asthma. However, little is known about accompanying IgG and subclass responses and how they might relate to asthmatic outcome.

OBJECTIVE

To characterize hen's egg ovalbumin (OVA) IgG and subclass responses through the first 5 years of life in relation to duration of egg sensitization and later asthma.

SUBJECTS AND METHODS

The subjects (n=46) formed part of a larger cohort, born to atopic parents, who had been evaluated prospectively for the development of asthma. Egg sensitization was classified as transient (positive egg skin prick test at 1 year only) or persistent (positive skin test for at least 2 years). Plasma OVA IgG, IgG1 and IgG4 concentrations at birth (cord), 6 months, 1 and 5 years of age were measured by ELISA.

RESULTS

The kinetics of OVA IgG and IgG1 responses, but not IgG4, differed between egg sensitized and non-egg sensitized (NES) children. Only persistently sensitized children had a rise in OVA IgG1 concentration through the first year of life, and at 1 year of age they had significantly higher OVA IgG and IgG1 than either transiently sensitized or NES children. High OVA IgG1 was associated with later asthma: at 1 year of age, OVA IgG1 greater than 14,500 U predicted asthma with a sensitivity 64% and specificity 74%.

CONCLUSION

OVA IgG and subclass responses relate to the duration of egg sensitization. Measurement of OVA IgG1 concentration in infancy might offer a useful adjunct to identify those at an increased risk of asthma.

IgG and IgA antibody levels to cow's milk are low at age 10 years in children born preterm

BACKGROUND

Both innate and specific defenses of the preterm infant are even less developed than those of term infants, and the immune systems of preterm infants might be skewed differently at birth. Their immune responses to food antigens started early in life might therefore differ from those of term infants.

OBJECTIVE

We sought to compare antibody levels to cow's milk, ovalbumin, and gliadin at age 10 years in children who had been born either preterm or at term.

METHODS

IgG and IgA isotype antibodies to whole cow's milk, beta-lactoglobulin, alpha-casein, and ovalbumin, as well as IgG antibody levels to gliadin and to tetanus and diphtheria toxoids, were measured for a group of 62 children born preterm and 61 control subjects born at term. These children were studied at the same time for atopy.

RESULTS

Children born preterm had markedly lower levels of antibodies to cow's milk and to its protein fractions (P <.0001 for IgA and IgG antibodies to cow's milk and alpha-casein and IgG beta-lactoglobulin antibodies). IgG gliadin antibodies were also significantly lower in the preterm group (P =.03), although the difference was not significant for IgG ovalbumin antibodies. In the preterm group both those born before gestational week 30 and those given cow's milk-based formula early (before day 50) had the lowest levels of cow's milk antibodies. In the preterm group atopy was associated with low levels of IgG cow's milk antibodies but with high levels of IgG ovalbumin antibodies.

CONCLUSIONS

Early introduction of food antigens into the immature gastrointestinal tract of preterm infants might result in tolerance. The presence of less atopy in these children might also be a result of tolerance development.

Do levels of immunoglobulin G antibodies to foods predict the development of immunoglobulin E antibodies to cat, dog and/or mite?

BACKGROUND

In children at high risk of inhalation allergy, food sensitization is associated with an increased risk for sensitization to inhalant allergens. Furthermore, this association was also found in a cross-sectional study.

OBJECTIVE

To examine in a prospective study, whether levels of IgG to foods (i.e. mixture of wheat and rice, mixture of soy bean and peanut, egg white, cow's milk, meat, orange and potato) indicate an increased risk for the future development of IgE antibodies to inhalant allergens in a low-risk population and whether they can be used as predictors of the subsequent development of IgE antibodies in young, initially IgE-negative children.

METHODS

Coughing children, aged 1-5, visiting their GPs, were tested for IgE antibodies to mite, dog and cat (RAST) and IgG (ELISA) to foods. All IgE-negative children were retested for IgE antibodies after two years. The IgG results (66 percentiles) of the first blood sample were compared to the RAST-scores of the second blood sample.

RESULTS

After two years, 51 out of 397 (12.8%) originally IgE-negative children, had become IgE-positive for cat, dog and/or mite. An increased IgG antibody level to wheat-rice (OR = 2.2) and to orange (OR = 2.0) indicated an increased risk of developing IgE to cat, dog or mite allergens. In addition to IgG to a mixture of wheat-rice and orange; total IgE, breastfeeding, eczema as a baby and age were the most important predictors for the subsequent development of IgE to inhalant allergens.

DISCUSSION

An increased IgG antibody level to a mixture of wheat-rice or orange, indicates an increased risk of developing IgE to cat, dog or mite allergens. This indicates that excessive activity of the mucosal immune system is present before IgE antibodies to airborne allergens can be demonstrated. Nevertheless, IgG to foods is not very helpful (with a positive predictive value of 16.5%, and negative predictive value of 90.6%) in identifying individual children at risk in clinical practice. However, besides other risk factors, IgG to wheat-rice and to orange could be useful as a screening test for studies in the early identification, i.e. before IgE antibodies can be detected, of children with an increased risk of developing IgE antibodies in the future.

Cellular immune responses to ovalbumin and house dust mite in egg-allergic children

BACKGROUND

Although IgE-mediated food (egg) allergy is typically lost with age the underlying immune mechanisms are not understood, particularly in relation to the development of persistent IgE-mediated aeroallergen sensitivity.

METHODS

Lymphoproliferation and cytokine responses (IL-5, IL-10, IL-13 and IFN-gamma) to house dust mite (HDM) allergen and egg ovalbumin (OVA) were assessed using peripheral blood mononuclear cells (PBMC) from children aged 6 months to 5 years (n = 59) with acute IgE-mediated egg allergy (urticaria and angiedema or anaphylaxis), as confirmed by positive skin prick testing (SPT). Of these 46 had positive SPT on the day of blood collection and 13 had outgrown egg allergy (negative SPT and successful egg challenge). Where possible, responses were compared with previous data from nonallergic children of similar ages (n = 107).

RESULTS

Transient lymphoproliferative responses to OVA were seen in both egg-allergic and nonallergic children, but were more marked and more prolonged in egg-allergic children. Younger egg-allergic children (< 18 months) showed a mixed Th0 cytokine response to OVA, with readily detectable IFN-gamma, IL-5, IL-13 IL-10. Although IL-13 and IL-5 responses (OVA) correlated in younger egg-allergic children, there was a dissociation of these Th2 responses with age. Loss of clinical reactivity to egg was associated with almost complete loss of IL-5 responses and OVA-specific lymphoproliferation. Although IL-13 levels tended to be lower with age, this was not significant. Strong IFN-gamma and IL-10 responses to OVA persisted in older children after loss of OVA-specific lymphoproliferation. Lymphoproliferative responses to HDM also developed earlier in egg-allergic children compared with nonallergic children. Th1 (IFN-gamma) responses to HDM were largely below detection prior to 18 months of age, but increased significantly with age. In egg-allergic children Th2 (IL-5, IL-13) HDM responses also progressively increased with age. At 3 years of age almost all egg-allergic children had positive SPT to HDM and positive lymphoproliferative responses to HDM, with strong Th1 and Th2 (Th0) cytokine production.

CONCLUSIONS

IL-5 responses (rather than IL-13) responses most closely reflected clinical food allergy, with dissociation of IL-5 and IL-13 responses in older and egg-tolerant children. In this population, food and aeroallergen sensitivity was not associated with inability to produce IFN-gamma, but rather with mixed Th2 and Th1 (Th0) responses. Strong IL-10 and IFN-gamma responses where associated with the development of tolerance, suggesting persistent 'regulatory' populations of OVA-specific T cells, rather than clonal deletion of OVA responsive T-cells.