Abstract
The Revovery-ELISA (R-ELISA) resembles a combination of a Sandwich-ELISA for the antigen and a competitive ELISA for the therapeutic antibody.
The R-ELISA is a special ELISA application for presence of an additional TAb in the measuring system. The special feature is a two-dimensional calibration, which performs a calibration for the antigen without and with addition of the therapeutic antibody and a calibration of the antigen-recovery in dependence of the therapeutic antibody.
Addition of Omalizumab to the IgE-Sandwich-ELISA reduced the optical density of the signal in a non-linear manner for the detection of IgE. At 7,2 μg/ml Omalizumab the IgE-signal is reduced for 75%. The addition of substrate to the assay enables the re-calculation for real samples. The Fig. shows the antigen recovery in dependence of Therapeutic antibody.
The therapeutic effect of the therapeutic antibody is visible on recovery curve. This curve shows the remaining percentage of free antigen = recovery under therapy. The assay runs in serum dilutions of 1:20.
This recovery curve demonstrates that the efficacy of antibody therapy in concentrations higher than 2 μg/ml Omalizumab (=40 μg/ml in undiluted serum) becomes rather low. In clinical samples was found similar IgE concentration within a wide range of high Omalizumab activity.
Using the R-ELISA it will be possible to calculate a maximal effective dose of TAb.
- © 2011 ERS