Renate L. Bergmann

Early exposure to house-dust mite and cat allergens and development of childhood asthma: a cohort study

BACKGROUND In a prospective birth-cohort study, we assessed the relevance of mite and cat allergen exposure for the development of childhood asthma up to age 7 years. METHODS Of 1314 newborn infants enrolled in five German cities in 1990, follow-up data at age 7 years were available for 939 children. Assessments included repeated measurement of specific IgE to food and inhalant allergens, measurement of indoor allergen exposure at 6 months, 18 months, and 3 years of age, and yearly interviews by a paediatrician. At age 7 years, pulmonary function was tested and bronchial hyper-responsiveness was measured in 645 children. FINDINGS At age 7, the prevalence of wheezing in the past 12 months was 10.0% (94 of 938), and 6.1% (57 of 939) parents reported a doctors diagnosis of asthma in their children. Sensitisation to indoor allergens was associated with asthma, wheeze, and increased bronchial responsiveness. However, no relation between early indoor allergen exposure and the prevalence of asthma, wheeze, and bronchial hyper-responsiveness was seen. INTERPRETATION Our data do not support the hypothesis that exposure to environmental allergens causes asthma in childhood, but rather that the induction of specific IgE responses and the development of childhood asthma are determined by independent factors.

Early childhood infectious diseases and the development of asthma up to school age: a birth cohort study

Abstract Objective: To investigate the association between early childhood infections and subsequent development of asthma. Design: Longitudinal birth cohort study. Setting: Five childrens hospitals in five German cities. Participants: 1314 children born in 1990 followed from birth to the age of 7 years. Main outcome measures: Asthma and asthmatic symptoms assessed longitudinally by parental questionnaires; atopic sensitisation assessed longitudinally by determination of IgE concentrations to various allergens; bronchial hyperreactivity assessed by bronchial histamine challenge at age 7 years. Results: Compared with children with 1 episode of runny nose before the age of 1 year, those with 2 episodes were less likely to have a doctors diagnosis of asthma at 7 years old (odds ratio 0.52 (95% confidence interval 0.29 to 0.92)) or to have wheeze at 7 years old (0.60 (0.38 to 0.94)), and were less likely to be atopic before the age of 5 years. Similarly, having 1 viral infection of the herpes type in the first 3 years of life was inversely associated with asthma at age 7 (odds ratio 0.48 (0.26 to 0.89)). Repeated lower respiratory tract infections in the first 3 years of life showed a positive association with wheeze up to the age of 7 years (odds ratio 3.37 (1.92 to 5.92) for 4 infections v 3 infections). Conclusion: Repeated viral infections other than lower respiratory tract infections early in life may reduce the risk of developing asthma up to school age.

Indoor allergen exposure is a risk factor for sensitization during the first three years of life

BACKGROUND The purpose of the study was to investigate the influence of environmental allergen exposure on allergic sensitization in infancy and early childhood. METHODS A cohort of 1314 newborns was recruited and followed up prospectively at the ages 12, 24, and 36 months. The levels of major mite (Der p 1 and Der f 1) and cat (Fel d 1) allergens were determined from domestic carpet dust samples by sandwich ELISA. Specific serum IgE antibodies to mite and cat allergens were determined by CAP fluoroimmunoassay (Pharmacia). Logistic regression was used to assess the effects of allergen exposure, age, family history, and cord blood IgE simultaneously on the risk of sensitization. RESULTS Children, who had been found to be sensitized at least once during the first 3 years of life, were found to be exposed to significantly higher house dust mite (median, 868 ng/gm vs 210 ng/mg; p = 0.001) and cat (median, 150 ng/gm vs 64 ng/gm; p = 0.011) allergen concentrations in domestic carpet dust compared with the group without sensitization. In homes with low (< or = 25th percentile) dust concentrations, the risk of sensitization to mite (1.6%), and cat (2.0%) is low, compared with 6.5% for mite and 6.3% for cat if the domestic exposure is above the 75th percentile. The dose-response relationships between allergen levels and sensitization indicate that the increase in sensitization risk at low allergen levels is more pronounced in cat allergy (p = 0.002) than in mite allergy (p = 0.026). In the group with a positive family history, lower mite and cat allergen concentrations are needed to achieve specific sensitization compared with the group with a negative family history. CONCLUSION Our data indicate that avoidance measures in the domestic environment aimed at the primary prevention of allergen-driven sensitization should be introduced at the earliest possible stage, if possible during infancy.

Natural course of sensitization to food and inhalant allergens during the first 6 years of life

BACKGROUND Specific IgE antibody responses to alimentary and environmental allergens are one of the hallmarks of atopic diseases. The knowledge of the time course of allergic sensitization during early life may facilitate measures for preventive interventions. OBJECTIVE In a prospective birth cohort study (the Multicenter Allergy Study [MAS]) we investigated annual incidence and prevalence rates of sensitization to food and inhalant allergens during the first 6 years of life. METHODS For 216 children of a prospective birth cohort (MAS), a complete follow-up of specific IgE measurements to 9 food and inhalant allergens was available at 1, 2, 3, 5, and 6 years of age. On the basis of these measurements, sensitization rates were estimated for the reference population of 4082 children by weighted analysis. RESULTS Annual incidence rates of sensitization to food allergens decreased from 10% at 1 year of age to 3% at the 6 years of age. Incidences of sensitization to inhalant allergen, however, increased with age (from 1.5% at 1 year to 8% at 6 years). Point prevalences of allergic sensitization to at least 1 of the 9 tested allergens increased from 11% at 1 year up to 30% at 6 years. This increase was due to markedly increasing sensitization rates to inhalant allergens (1.5% to at least 1 inhalant allergen at 1 year and 26% at 6 years of age), whereas sensitization rates to food allergens remained stable during the first 6 years of life (10%). CONCLUSION The earliest serologic marker for atopic immunoreactivity in infancy is the presence of IgE antibodies to egg, followed by milk. The development of sensitization to inhalant allergens occurs mostly after infancy. Beyond the third birthday annual incidence and prevalence increase markedly with age. Rates for outdoor allergens are twice those for indoor allergens.

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 hens 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 Hens 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 determinants of childhood overweight and adiposity in a birth cohort study: role of breast-feeding

BACKGROUND: The prevalence of adiposity in childhood is increasing. Is breast-feeding protective as suggested by cross-sectional studies?OBJECTIVE: In a longitudinal birth cohort study, we tested whether breast-feeding for more than 2 months has preventive effects against overweight and adiposity at 6 y.DESIGN: Of 1314 children representing the catchment areas of six delivery units, 918 could be followed up to the age of 6 y. Height, weight, and skin-fold thickness were measured at regular visits. As the criteria of overweight, obesity, and adiposity in the children, the 90th and the 97th percentiles of BMI and skin-fold values were used. Parents with a BMI at or above the 90th percentile, which was 27 kg/m2 or more, were considered overweight. Infants bottle-fed from birth or breast-fed for less than 3 months were classified as ‘bottle-fed’ (BO), and those breast-fed for 3 months and more as ‘breast-fed’ (BR). Univariate comparisons and logistic regression analysis were performed applying SAS 6.12. The final logistic model consisted of the 480 cases for whom complete data for all variables were available. The potential effect of loss to follow-up was analysed by the Cochran–Mantel–Haenzel test: the outcomes were not significantly influenced by loss to follow-up.RESULTS: At birth BMIs were nearly identical in both groups. By 3 months, BO had significantly higher BMIs and thicker skin folds than BR. From 6 months on, compared to BR, a consistently higher proportion of BO children exceeded the 90th and the 97th percentile of BMI and skin-fold thickness reference values. From the age of 4 y to 5 and 6 y, in BO the prevalence of obesity nearly doubled and tripled, respectively. With only minor changes of obesity prevalence in BR, the difference of BMI and skin-fold thickness between groups became statistically significant. Logistic regression analysis revealed that overweight of the mother, maternal smoking during pregnancy, bottle feeding, and low social status remained important risk factors for overweight and adiposity at 6 y of age.CONCLUSION: A maternal BMI of ≥27, bottle-feeding, maternal smoking during pregnancy, and low social status are risk factors for overweight and adiposity at 6 y of age. Early bottle-feeding brings forward the obesity rebound, predictive of obesity in later life.

Prevalence and role of serum IgE antibodies to the StaphylococcuS aureus–derived superantigens SEA and SEB in children with atopic dermatitis

BACKGROUND The skin of patients with atopic dermatitis exhibits a striking susceptibility to colonization and infection with Staphylococcus aureus. In this context it has been previously shown that S aureus-derived superantigens could function as classic allergens, inducing production of functionally relevant specific IgE antibodies. OBJECTIVE The aim of this study was to determine the prevalence and the role of circulating staphylococcal enterotoxin A (SEA)- and staphylococcal enterotoxin B (SEB)-specific IgE antibodies in children with atopic dermatitis. METHODS In a cross-sectional study of 58 children with atopic dermatitis, the presence of IgE antibodies to SEA and SEB was correlated with the severity of the disease and the total and other unrelated allergen-specific IgE titers and density of colonization with S aureus strains on atopic skin and episodes of superficial S aureus skin infections. RESULTS Twenty of 58 children (34%) were sensitized to superantigens (45% to SEB, 10% to SEA, 45% to SEA and SEB). In this group, severity of atopic dermatitis and levels of specific IgE to food and air allergens were significantly higher. The degree of disease severity correlated to a higher extent with the presence of SEA/SEB-specific antibodies than with total serum IgE levels. Density of colonization with superantigen-secreting S aureus strains was higher in the superantigen IgE-positive group. Sixty-three percent of these children experienced repeated episodes of superficialS aureus skin infections. CONCLUSIONS Sensitization to S aureus-derived superantigens may be involved in disease exacerbation. The presence of SEA/SEB-specific antibodies had additional explanatory value for disease severity and therefore may be helpful in the characterization of children with severe atopic dermatitis.

Breastfeeding duration is a risk factor for atopic eczema

Background The results of numerous studies on the influence of breastfeeding in the prevention of atopic disorders are often contradictory. One of the most important problems is confounding by other lifestyle factors.

Predictability of early atopy by cord blood‐IgE and parental history

Background Atopic family history and cord blood IgE have been used as predictors of atopic disease in newborns for about 20 years, but at least for cord blood IgE the sensitivity has been shown to be very low. The objective of this paper was to evaluate whether parental history and cord blood‐IgE were more accurate predictors for the appropriate atopic phenotypes in the infants rather than for any atopy.

Effect of pre‐ and postnatal tobacco smoke exposure on specific sensitization to food and inhalant allergens during the first 3 years of life

Background: The study aimed to assess the effect of pre‐ and postnatal tobacco smoke exposure on specific sensitization to food allergens and inhalant allergens during the first 3 years of life.