RELATIONSHIP OF INDOOR ALLERGEN EXPOSURE TO SKIN-TEST SENSITIVITY IN INNER-CITY CHILDREN WITH ASTHMA

Background: It is important to understand the relationship between env ironmental allergen exposure dose and the risk of atopic individuals b ecoming sensitized to that allergen if we are to change the risk of se nsitization and morbidity from allergic disease. Objective: The object ive of these studies was to determine whether there was a dose respons e between current exposure to mite, cockroach, and cat allergen in inn er-city children and to determine the prevalence of sensitization to t hese allergens. Methods: A sample of 500 children was selected from th e 1528 children enrolled in the National Cooperative Inner City Asthma Study. Children were selected who had a sample of home dust and valid skin test responses performed with a MultiTest skin test device. The samples of home dust were collected from the floor and furniture in th e kitchen, bedroom, and television/living room and were assayed for De r p 1, Der f 1, Bla g 1, and Eel dl allergens. Results: Each allergen level correlated significantly between rooms in individual homes. Mite (Der p 1 and Der f 1) and cat (Fel d 1) allergen levels were frequent ly below the detection limit of the assay. Cockroach allergen (BLa g 1 ) concentrations in the child's bedroom were related to the prevalence of positive skin test responses to cockroach allergen extract among t he children, with an odds ratio for sensitization of 1.45 (1.11-1.92). Positive skin test responses to cockroach allergen were seen in 15% o f children exposed to bedroom dust with a Bla g 1 concentration below the level of detection compared with a rate of 32% in bedrooms with Bl a g 1 levels of 1 to 2 U/g and 40% to 44% among those in rooms with 4 U/g or greater. The relationship between exposure and positive skin te st responses was clearly stronger among atopic children with a greater number of positive skin test responses. Conclusions: Despite widespre ad exposure to household allergens, the strongest relationship between exposure and sensitization was seen in the bedroom. The dose response between exposure to cockroach allergen and sensitization suggested th at exposure to low doses of allergen, 2 U/g or less, was a risk factor and that the risk plateaus above 4 U/g. Atopy modified the relationsh ip of exposure to sensitization.