PURPOSE OF THE STUDY.
To use clinical, serological, and environmental exposure data to evaluate the prevalence of food allergy (FA) and the contribution of environmental exposures on sensitization and allergy in a population of inner-city children.
The study enrolled 560 children from the Urban Environment and Childhood Asthma birth cohort (≥34 weeks’ gestation) with a parental history of allergic disease or asthma, cord blood sample, and food-specific immunoglobulin (Ig)E levels measured.
Pregnant women were enrolled and their children followed from birth to age 5 years. Mothers completed prenatal environmental exposure questionnaires and yearly clinical history/exposure questionnaires, and children were seen annually for detailed history of symptoms and exposures. Serum IgE to milk, egg, and peanut was obtained at ages 1, 2, 3, and 5 years, and blood cytokines were obtained at birth, 1 and 3 years. Household dust samples were collected at age 3 months and annually for indoor allergens, endotoxin, and ergosterol. Children were grouped based on sensitization (IgE ≥0.35 kU/L to milk, egg, and/or peanut) including the following: (1) FA (sensitized on dietary avoidance and confirmed reaction to food), (2) possible FA (sensitization with either dietary avoidance or unknown consumption and no confirmed reaction), (3) sensitized but tolerant (consumed food without reaction), and (4) not sensitized.
Of those enrolled, 55.4% were in a food-sensitized group (47% milk, 31% egg, 21% peanut) and were classified as follows: 9.9% FA (2.7% milk, 4.3% egg, 6.0% peanut); 17% possible FA; 28.5% sensitized but tolerant. FA was associated with breastfeeding, recurrent wheeze, eczema, aeroallergen sensitization, male gender, and low environmental endotoxin exposure. Other environmental exposures were similar in groups with and without food sensitization/allergy. IgG4 levels were higher in sensitized and FA patients than in the nonsensitized group, and FA children had altered innate/adaptive immunity, per cytokine profiles.
This study found the incidence of FA in inner-city children to be higher than in the average pediatric population with potential environmental risk factors delineated.
This study is the first to use prospective clinical and serological data along with environmental exposure history to demonstrate a high incidence of FA in inner-city children. The study was also among the first to look at longitudinal exposures common in an urban environment and their effect on development of FA and sensitization demonstrating that environmental endotoxin exposure was associated with a lower incidence of FA. This study leaves us with the opportunity for more directed research to discover modifiable risk factors associated with the development of FA and sensitization among high-risk urban populations.
- Copyright © 2015 by the American Academy of Pediatrics