A highly sensitive quantitative immunochromatography assay for antigen-specific IgE

We have developed a highly sensitive quantitative enzyme immunochromatography system for antigen-specific IgE, which is clinically important for the diagnosis of allergic diseases. The system uses alkaline phosphatase-labeled anti-IgE antibody (ALP-anti-IgE) and immobilized target antigen, for example cedar pollen antigen, on a membrane. Antigen-specific IgE present in the serum binds the immobilized antigen after complexing with the ALP-anti-IgE. Subsequently, the enzyme substrate migrates to the complex on the antigen line, which is stained blue. The intensity of the staining was analyzed by a quantitative detector, but can also be assessed directly by the naked eye. This system was able to detect 0.2 U/ml of IgE specific for Japanese cedar pollen. The results correlated well (Spearman's rank correlation coefficient, 0.95) to those in AlaSTAT system, which is a reliable enzyme-linked immunosorbent assay (ELISA) method. This antigen-specific IgE assay system is suitable for point-of-care testing.