Serum IgG and IgG4 antibodies to Fel d 1 among children exposed to 20 mu gFel d 1 at home: Relevance of a nonallergic modified Th2 response

Exposure to foreign antigens is an essential element of all immune response s, including allergic sensitization. For some allergens (e.g. mite and cock roach), the prevalence of sensitization is directly correlated with exposur e. However, for allergens derived from domestic animals, several studies ha ve suggested that children with a cat in the home have a decreased risk of sensitization and asthma. We have now shown that many children exposed to g reater than 20 mug of Fel d 1/g of dust at home made an IgG and IgG4 antibo dy response to Fel d 1 without IgE antibody. This modified Th2 response is not associated with symptoms and should be regarded as a form of immunologi cal tolerance. The fact that the dose-response relationship between cat exp osure and sensitization is bell shaped, while that for mite exposure and se nsitization is linear, is highly relevant to understanding the role of alle rgens in the increase in allergic disease. Copyright (C) 2001 S. Karger AG, Basel.