IgG and IgE antibody responses to dust mite allergens among children with asthma in Brazil.

We compared exposure and levels of IgE and IgG antibodies to inhalant allergens in 20 children with asthma and positive skin tests to Dermatophagoides pteronyssinus, living in São Paulo, to 20 control children without history of asthma or allergy and negative skin tests to D. pteronyssinus, D. farinae, and Blomia tropicalis. In 16/20 and 17/20 houses of asthmatic and control children, respectively, at least one sample was obtained which contained > 10 micrograms Der p I/g of dust. Serum IgE antibodies to D. pteronyssinus and Blomia tropicalis were > 200 RAST U/mL in 19/20 and in 16/20 asthmatic children, respectively. In the control group, IgE antibodies to either mite species were < 40 RAST U/mL in most cases. IgG anti-Der p I and anti-Der f I antibodies were detected in 17/20 asthmatics, as opposed to 3/20 controls. Neither cat nor cockroach allergens caused significant sensitization among asthmatic or control children. Although exposure to high levels of mite allergens was common in São Paulo, significant IgE and IgG antibody responses were detected only in children with asthma.