Prediction and detection of allergy development: influence of genetic and environmental factors

An investigation of airborne allergenic pollen at different heights

BACKGROUND AND AIMS

Airborne pollen is an important source of allergens in a number of allergic diseases. Data on the concentrations of pollen at different heights in the air are scarce. The aim of the present study was to investigate different types and numbers of airborne pollen and their seasonal variation at different heights in the urban area of Shenzhen (China) and their associations with meteorological factors.

METHODS

The concentration of airborne pollen at different heights was monitored with Burkard traps from July 1, 2006, to June 30, 2007, in Shenzhen; the results were analyzed with SAS 9.13 software.

RESULTS

In total, 1,095 films (at 3 heights, 365 films at each height) were exposed throughout the year, and 48 families and 85 genera of pollen taxa were identified. The total pollen count was 55,830 grains (25,204 grains at 1.5 m; 16,218 grains at 35 m, and 14,408 grains at 70 m); pollen grains were present in the atmosphere throughout the year, with two peaks of airborne pollen: one peak in February to April and the other in September to November.

CONCLUSIONS

On the basis of our local investigations, the pollen concentrations and the pollen types in the air decrease gradually with increasing height. The distribution and concentrations of airborne pollen at different heights in the atmosphere were influenced by composite factors such as the season and meteorological factors.

The role of allergic risk and other factors that affect the occurrence of atopic dermatitis in the first 6 months of life

Background

Atopic dermatitis (AD) is a chronic inflammation of the skin that often appears in early childhood. The manifestation is related to the tendency towards T helper 2 cytokine immune responses (interleukin (IL)-4, IL-5). Genetic factors are suggested to play important roles in AD, and it can be transmitted to newborns, increasing their risk of developing allergies.

Objective

To determine the association between cord-blood cytokine levels (IL-5, interferon (IFN) γ), cord-blood total immunoglobulin E (IgE) level, perinatal environmental exposure, and the risks of allergy as well as the development of AD in the first 6 months of life.

Methods

A 6-month cohort study with a nested case-control within was conducted on newborns in Jakarta from December 2008 until May 2009. After the umbilical cord blood samples were taken and stored, subjects were followed up monthly until 6 months old. The occurrence of AD and lifestyle or environmental exposures were recorded. The allergic risk was determined using a modified pediatric allergy immunology work groups scoring system based on allergic history (allergic rhinitis, asthma, AD) in the family. The levels of IL-5 and IFN-γ were measured using ELISA and total IgE by CAP system FEIA. Multivariate analysis was used to evaluate risk factors.

Results

This study was conducted on 226 subjects. The incidence of AD was 16.4%; of those, 59% had low risk allergy, 38.5% moderate, and 2% high risk. AD mostly occurred at the age of 1 month (57%). Cord blood samples were examined in 37 subjects with AD and 51 without AD; of those, 25% showed high levels of total IgE (>1.2 IU/µL), and 51% showed normally-distributed high absorbance IL-5 values (≥0.0715, absolute value was undetected). The increased level of IL-5 was directly proportional to IgE. High absorbance IFN-γ values (≥0.0795, absolute value = 18.681 pg/µL) were observed in 52% of subjects.

Conclusion

The associations between the risk of allergy in the family, cord-blood total IgE, IL-5, IFN levels, and some perinatal environmental exposure with AD in the first 6 months of life have not been established.

Mopane worm allergy in a 36-year-old woman: a case report

INTRODUCTION

The increasing incidence of new diseases as well as changing features of known diseases has partly been attributed to the impact of environmental changes. As a result, there have been calls from health experts for proper surveillance and monitoring of these changes.This is a report of mopane worm allergy in a 36 year old female from the Tswana tribe in Botswana. Mopane worm, the caterpillar stage of Gonimbrasia belina moths, is a seasonal delicacy to people in many communities in southern Africa. As a result, by adulthood, many residents of these communities have had substantial exposure to the worm. Gonimbrasia belina moths belong to the Lepidoptera order of insects. Though some members of this order are known to induce contact allergy, there is no reported incidence of ingestion allergy from mopane worm. Therefore, it is important to track this case for its epidemiological significance and to alert both clinicians and the vulnerable public on the incidence of mopane worm allergy in this region.

CASE PRESENTATION

This is a case of a 36 year old woman from the Tswana ethnic group in Botswana, who was diagnosed with food allergy. She presented with itchy skin rash, facial swelling, and mild hypotension after eating mopane worm. She had no previous history of allergic reaction following contact or ingestion of mopane worm and had no atopic illness in the past. She was treated and her symptoms resolved after 4 days.

CONCLUSION

The proper management of allergy involves patients' avoidance and clinicians' predictability. Though hypothetical, this report is expected to sensitize clinicians to anticipate and properly manage subsequent occurrence, as well as educate the public in these communities. In addition, tracking new disease patterns, with relationship to environmental changes, will compliment existing evidence in validating the importance of proper environmental surveillance and management.

Pharmacokinetics in special populations

Pharmacokinetics are typically dependent on a variety of physiological variables (e.g., age, ethnicity, or pregnancy) or pathological conditions (e.g., renal and hepatic insufficiency, cardiac dysfunction, obesity, etc.). The influence of some of these conditions has not always been thoroughly assessed in the clinical studies of antiallergic drugs. However, the knowledge of the physiological grounds of the pharmacokinetics can provide some insight for predicting the potential alterations and guiding the initial prescription strategies. It is important to recognize that both pharmacokinetic and pharmacodynamic differences between populations should be considered. The available information on drugs used for the therapy of allergic diseases is reviewed in this chapter.

Risk factors for the development of food allergy

Both genetic and environmental factors seem to predispose to the development of food allergy. A most notable factor is diet, particularly during infancy. Possible other factors include maternal diet during pregnancy and lactation, birth by cesarean section, exposure to tobacco smoke, multivitamin supplementation, and intake of antacids. It is important to identify and control such risk factors to reduce the development of food allergy.

Infantile eczema at one month of age is associated with cord blood eosinophilia and subsequent development of atopic dermatitis and wheezing illness until two years of age

BACKGROUND

Physiological and pathological skin eruptions are commonly encountered in neonates in our clinical practice. However, the types of skin eruptions that are associated with the subsequent development of atopic dermatitis and the mechanisms of these associations remain uncertain.

METHODS

A total of 105 newborn babies with normal delivery were enrolled in this prospective cohort study. The cord blood eosinophil count was measured and the neonates were examined at 1 month of age and followed until 8 years of age.

RESULTS

At 1 month of age, infantile eczema, seborrheic dermatitis, intertrigo and diaper dermatitis were diagnosed in a total of 29, 7, 14 and 24 neonates, respectively. No association was found among the prevalences of these eruptions. Neonates with infantile eczema had a significantly higher number and ratio of eosinophils in the cord blood (eosinophil count: 670.8 +/- 67.8 vs. 349.0 +/- 30.3/microl, p < 0.0001; eosinophil ratio: 5.12 +/- 0.53 vs. 2.61 +/- 0.22%, p < 0.0001, for the presence and the absence of infantile eczema, respectively). In contrast, no such tendency was found for any other skin eruptions. In neonates with infantile eczema at 1 month of age, the diagnosis of atopic dermatitis had been made significantly earlier and the prevalence of wheezing illness was significantly higher than in those without infantile eczema until 2 years of age.

CONCLUSION

Infantile eczema, but not other skin eruptions, precedes the development of atopic dermatitis and wheezing illness during early infancy, presumably because of the activation of eosinophils before birth.

Early sensitisation and development of allergic airway disease - risk factors and predictors

The development and phenotypic expression of allergic airway disease depends on a complex interaction between genetic and several environmental factors, such as exposure to food, inhalant allergens and non-specific adjuvant factors (e.g. tobacco smoke, air pollution and infections). The first months of life seem to be a particularly vulnerable period and there is evidence that sensitisation is related to the level of allergen exposure during early life. At present, the combination of atopic heredity and elevated cord-blood IgE seems to result in the best predictive discrimination as regards development of allergic disease at birth. Early sensitisation, cow's milk allergy and atopic eczema are predictors for later development of allergic airway disease. Exposure to indoor allergens, especially house dust mite allergens, is a risk factor for sensitisation and development of asthma later in childhood in high-risk infants and infants with early atopic manifestations.

How should a birth cohort study be organised? Experience from the German MAS cohort study

Birth cohort studies offer the opportunity to study average risks, rates and occurrence times of disease longitudinally from birth. The effect of genetic and environmental factors and their interactions can be studied. Furthermore, quantity and duration of exposure to environmental agents can be evaluated prospectively. However, prospective birth cohort studies are expensive, labour intensive and take many years to complete. Loss of subjects over time as well as recall bias complicate the interpretation of observations. This paper summarises the potential pitfalls of such studies and discusses the experience of the German Multicentre Allergy Study (MAS), which began in 1990 in five German cities and included 1314 newborns for the study of the natural course of atopic diseases.

Prediction of sensitization to inhalant allergens in childhood: evaluating family history, atopic dermatitis and sensitization to food allergens. The MAS Study Group. Multicentre Allergy Study

BACKGROUND

A family history of atopy is a poor predictor of sensitization to inhalant allergens and allergic disease during childhood. We recently identified early sensitization to food allergens, especially hen's egg, as a valuable predictor of subsequent sensitization to inhalant allergens.

OBJECTIVE

(1) Whether prediction will be improved by in vitro allergy tests at 1 year of age in combination with family history and medical history data. (2) Comparison with the capacities of in vitro tests to predict sensitization to aeroallergens.

METHODS

Of an observational birth cohort study (MAS) 49 children who were sensitized to inhalant allergens at 5 years of age and 116 non-sensitized controls were included in the present study. For the prediction of sensitization to inhalant allergens the following prognostic factors were evaluated: atopic family history (FH), atopic dermatitis (AD) during the first year of life, two in vitro allergy tests for specific IgE to common food allergens at 1 year of age (fx5 [Pharmacia] and single allergen specific tests (sIgE) for four allergens) and 'high' total serum IgE, defined by three different cut off points.

RESULTS

The combination of medical history data and laboratory tests resulted in the best predictive discrimination. The positive predictive values (PPV) were higher if sensitization to food was detected by single allergen specific tests (PPV: 66%/75%/100% corresponding to the three evaluated risk groups) than by the qualitative fx5 (PPV: 46%/65%/100%). The negative predictive values were equal for both tests (69 and 92% for the two low risk groups). High total serum IgE had low predictive capacity.

CONCLUSION

During infancy the prediction of sensitization to inhalant allergens should be based on medical history data and allergy tests determining sensitization to food allergens. The in vitro tests improve the predictive discrimination, but the individual risk profile of the child must be considered for a reliable and valid prediction.

Long-lasting sensitization to food during the first two years precedes allergic airway disease. The MAS Study Group, Germany

The purpose of the study was to investigate whether the duration of sensitization to food allergens during early childhood is related to later development of IgE mediated hypersensitivity to inhalant allergens and of allergic rhinitis and asthma in 5-year-old children and whether long-lasting food-sensitization may be used to predict subsequent allergic airway diseases. Five hundred and eight children of a prospective birth cohort study with available serum samples at one and two years of age were included and followed up until five years of age. Specific sensitization to food and inhalant allergens and the occurrence of subsequent allergic airway diseases were determined. Children with a long-lasting sensitization to food allergens (persistently sensitized for more than one year) produced significantly higher total IgE and specific IgE levels than children who were only transiently food-sensitized by two years of age. Children persistently sensitized to food had a 3.4 fold higher risk of developing allergic rhinitis and a 5.5 fold higher risk of developing asthma than infants who were only transiently food sensitized. Persistent food sensitization in combination with a positive atopic family history was a strong predictor for the development of allergic rhinitis and asthma at five years of age. The risks for these children are up to 50%, and 67% respectively. Persistently detectable sensitization to food over more than one year in early childhood is a strong prognostic factor for subsequent allergic airway disease. Persistently food-sensitized children especially in atopic families have to be regarded as a high-risk group and should be considered for preventive measures against respiratory atopy.

Myths and facts about breastfeeding: does it prevent later atopic disease?

Exclusive human milk feeding during the first 6 months of life, with delayed introduction of solids, is the recommended feeding for human infants. Human milk reduces the incidence and morbidity related to infection and allergy to cow's milk proteins. Dietary maternal restrictions during (late) pregnancy or lactation cannot be recommended, but may be advised in special cases. A maternal elimination diet seems more effective if associated with environmental hypoallergenic intervention(s). Milk from mothers consuming cow's milk proteins contains small amounts of beta-lactoglobulin, which appear to introduce in the majority of infants both atopic and non-atopic tolerance rather than sensitization. However, it is uncertain whether breastfeeding also reduces the incidence of later atopic disease, since its aetiology is multifactorial.

Sensitization to hen's egg at the age of twelve months is predictive for allergic sensitization to common indoor and outdoor allergens at the age of three years

BACKGROUND

Specific predictors for atopic sensitization in early infancy are prerequisites for preventive intervention studies.

OBJECTIVE

To identify predictors of allergic sensitization to common aeroallergens in infancy, 1314 children in five German cities were followed up from birth (1990) to the age of 3 years.

METHODS

Blood samples were taken from cord blood and at follow-up visits at the ages of 1, 2, and 3 years. Total serum IgE and specific IgE antibodies to common food and inhalant allergens were determined.

RESULTS

Among our study population, risk factors for sensitization to indoor and/or outdoor allergens at the age of 3 years were a positive family history, the presence of hen's egg-specific IgE antibodies (> or = 0.35 kU/L), and increased log- [total IgE] levels at the age of 12 months. Elevated cord blood IgE was not associated with sensitization to inhalant allergens at the age of 3 years. Egg-specific IgE greater than 2 kU/L in combination with a positive family history of atopy was a highly specific (specificity, 99%) and predictive (positive predictive value, 78%) marker for sensitization to inhalant allergens at 3 years of age.

CONCLUSIONS

Hen's egg-specific IgE at the age of 12 months is a valuable marker for subsequent allergic sensitization to allergens that cause asthma, allergic rhinitis, and atopic dermatitis.

Early detection of specific IgE antibody against house dust mite in children at risk of allergic disease

OBJECTIVES

House dust mite (HDM) is a representative inhalant allergen that triggers allergic disease in childhood. The aim of this study is early detection of HDM-specific IgE antibody and prediction of the risk of a positive reaction to this antibody by in vitro parameters in infants with allergic manifestations.

STUDY DESIGN

Levels of HDM IgE in a range below the standard cutoff point of 0.35 U/ml, serum concentrations of IgE, and specific IgE antibodies against egg white, cow milk, and soybeans were determined in 108 infants with allergic manifestations at 6 months of age, and these infants were monitored for conversion of HDM IgE to positive levels greater than 0.35 U/ml up to 5 years of age. The presence of active allergic disease at 5 years of age in relation to HDM-specific IgE was also examined.

RESULTS

We were able to determine reliably the HDM IgE values between 0.23 and 0.35 U/ml, using a fluorescent enzyme immunoassay that measured the intensity of fluorescence. The HDM IgE levels increased, resulting in positive values, in 54 of 108 subjects during the first 5 years of life. In multiple regression analysis, an HDM IgE value between 0.23 and 0.35 U/ml, a high serum IgE level, and a positive reaction to specific IgE antibody against egg white in infants at 6 months of age proved to be significant predictors of the future positive reaction to HDM IgE (p = 0.0006, 0.0043, and 0.0001). In particular, the sensitivity and specificity of specific IgE antibody against egg white for the conversion of HDM IgE to positive values were the best among these indicators. Moreover, active allergic diseases were observed significantly more often in children with positive HDM IgE values than in children with negative HDM IgE values at 5 years of age (p < 0.001 for each).

CONCLUSIONS

A determination of these predictors in infants at 6 months of age can be used for early detection of HDM IgE and would be valuable in a screening test for later allergic disease among infants with allergic manifestations.

Effects of a dietary and environmental prevention programme on the incidence of allergic symptoms in high atopic risk infants: three years' follow-up

A prospective case-control study is presented to assess an allergy prevention programme in children up to 36 months of age. Infants born at three maternity hospitals were followed from birth: 279 infants with high atopic risk (intervention group) were compared with 80 infants with similar atopic risk but no intervention (non-intervention group). The intervention programme included dietary measures (exclusive and prolonged milk feeding diet followed by a hypoantigenic weaning diet) and environmental measures (avoidance of parental smoking in the presence of the babies, day care > 2 years of life). Mothers in this group who had insufficient breast milk were randomly assigned to one of two coded formulas: either a hydrolysed milk formula (Nidina HA, Nestlé) or a conventional adapted formula (Nan, Nestlé). Other environmental measures remained the same as for the breastfeeding mothers. The non-intervention group were either breastfed or received the usual Italian milk feeding and weaning diet, without environmental advice. The main outcome measures were anthropometric measurements and allergic disease manifestations. Normal anthropometric data were observed both in the intervention group and in the non-intervention group. The incidence of allergic manifestations was much lower in the intervention group than in the non-intervention group at 1 year (11.5 versus 54.4%, respectively) and at 2 years (14.9 versus 65.6%) and 3 years (20.6 versus 74.1%). Atopic dermatitis and recurrent wheezing were found in both the intervention group and the non-intervention group from birth up to the second year of life, while urticaria and gastrointestinal disorders were only present in the non-intervention group in the first year of life. Conjunctivitis and rhinitis were present after the second year in both the intervention group and the non-intervention group. Relapse of the same allergic symptom was less in the intervention group (13.0%) than in the non-intervention group (36.9%). In comparison to the non-intervention group, there were fewer intervention group cases with two or more different allergic symptoms (8.7 versus 32.6%), and they were more likely to avoid steroid treatment (0 versus 10.8%) and hospital admission (0 versus 6.5%). Babies in the non-intervention group fed with adapted formula were more likely to develop allergies than breastfed babies in the same group. In the intervention group the breastfed infants had the lowest incidence of allergic symptoms, followed by the infants fed the hydrolysed formula (ns). Infants in the intervention group fed the adapted formula had significantly more allergies than the breastfed and hydrolysed milk fed infants, although less than their counterparts in the non-intervention group. Of the affected subjects in the intervention group, 80.4% were RAST and/or Prick positive to food or inhalant allergens. Total serum IgE values detected at birth in the intervention group were not predictive, but at 1 and 2 years of age, IgE values more than 2 SD above the mean in asymptomatic babies were found to predictive for later allergy. In breastfed babies the total IgE level at 1 and 2 years of age was lower than in the other two feeding groups. Of the various factors tested in the non-intervention group, the following were the most important in the pathogenesis of allergic symptoms: (i) formula implementation begun in the first week of life; (ii) early weaning (< 4 months); (iii) feeding beef (< 6 months); (iv) early introduction of cow's milk (< 6 months); and (v) parental smoking in the presence of the babies and early day care admission (< 2 years of life). All the preventive measures used in this study (exclusive breastfeeding and/or hydrolysed milk feeding, delayed and selective introduction of solid foods, and environmental advice) were effective at the third year of follow-up, greatly reducing allergic manifestations in high atopic risk babies in comparison with those not receiving these interventions

Fecal IgE levels in infants at 1 month of age as indicator of atopic disease

Fecal IgE levels were investigated in 165 asymptomatic infants at 1 month of age under two nutritional regimens, breast-feeding and formula feeding, and the possibility of predicting by fecal IgE levels the onset of atopic disease was studied in these infants. IgE levels were measured by time-resolved fluoroimmunometric assay. IgE antibodies are detectable in fecal extracts, and we have already reported that IgE levels are increased in food-allergy patients after administration of food allergens, and this increase in fecal IgE levels may be a specific consequence of the local immune response to food-allergen stimulation in the gut mucosa. The presence of atopic disease and the feeding method during the nursing period were surveyed by questionnaire in 89 of these 165 infants when they were 18 months old. In an analysis of the present results, IgE values above 0.015 U/ml, the lower limit of measurement, were considered to be high. Forty-eight (29%) of the 165 subjects showed a high fecal IgE level. Thirty-seven (35%) of 105 formula-fed infants had high fecal IgE levels, whereas only 11 (18%) of 60 breast-fed infants had high levels (P < 0.05). With respect to atopic family history, 30 (39%) of the 77 infants with atopic family history had high fecal IgE levels, as compared with 18 (20%) of the 88 infants without atopic family history (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)