The importance of IgE antibody levels in anti-IgE treatment

Background: Dosages of anti-immunoglobulin (Ig)E in treatment of allergic asthma is based on total IgE body pool assuming that IgE antibodies responsible for the disease are evenly distributed among patients. This assumption was evaluated. Methods: Median and quartile concentrations of IgE and IgE antibodies to cat and mite in 6461 sera submitted to an allergy laboratory during 2003–2005 were calculated and expressed in groups of different IgE levels. Results: Of 3872 (60%) samples from adults with a serum IgE level of 30–700 kU/l, 22.2% had IgE antibodies (≥0.35 kUA/l) to mite, 36.0% to cat and 8.1% to both. The relative concentration of IgE antibody of IgE decreased with increasing IgE, indicating a more specific response in patients with slightly elevated serum IgE. At a hypothetical serum IgE level of 10 kU/l, the threshold recommended for anti-IgE treatment, 25% of the originally mite- and/or cat-positive population in the