Avila, L; Soto-Quiros, M; Odio, S; Hunt, JF; Carper, HT; Murphy, DD; O'Rourke, A; Davis, M; James, H; Platts-Mills, TAE; Heymann, PW
Rationale: Allergic sensitization, especially to dust mite, is common among children with asthma in Costa Rica. The relationship between allergen specific IgE responses to dust mite and airway inflammation, as judged by measurements of eNO, was evaluated among Costa Rican children who were treated for acute wheezing.
Methods: Children (7-12 years old) were enrolled in the emergency room at the Hospital Nacional de Niños, San José, Costa Rica: 44 with acute wheezing and 92 controls. Blood was obtained from each child for measurements of total serum IgE and allergen specific IgE antibody (ab) (Phadia ImmunoCAP Assay). Assessments of eNO (NIOX Mino, Aerocrine, Inc) were done in duplicate. The children were enrolled in February, during the dry season.
Results: Geometric mean (GM) levels of total IgE were significantly higher in sera from the wheezing children (433 IU/ml) than from controls (141 IU/ml) p<0.001. Among the wheezing children, the prevalence of IgE ab to dust mite was 88% to Dermatophagoides sp. (both D. pteronyssinus and D. farinae) and 91% to Blomia tropicalis compared to 44% and 48% among the controls; both p<0.001. The prevalence of IgE ab to cockroach among wheezing children was 48% to Blatella germanica and 36% to Periplaneta americana compared to 22% and 14% among controls, p<0.006 and p<0.007, respectively. The prevalence of IgE ab to 5 other allergens (Alternaria, Aspergillus, dog, cat, and Bahia grass) among the wheezing children was low and not significantly different from controls. Total IgE levels were significantly correlated with titers of IgE ab to dust mite (r = 0.73 for Dermatophagoides sp and r = 0.60 for Blomia tropicalis; both p<0.001), but not with titers to either cockroach species. Levels of eNO (GM) from the actively wheezing children (41 ppb) were significantly elevated compared to controls (17 ppb); p<0.001. Additionally, eNO measurements were significantly correlated with titers of IgE ab to dust mite (r = 0.68 for Dermatophagoides sp. and r = 0.48 for Blomia tropicalis; both p<0.001), but not with titers to either cockroach species.
Conclusions: Allergic sensitization to dust mite was common among school-aged children treated for wheezing in Costa Rica. Additionally, the titers of IgE ab to dust mite, especially Dermatophagoides sp., were strongly correlated with total IgE levels and significantly correlated with airway inflammation, as judged by levels of eNO.
