Assays for detecting antibodies specific to therapeutic anti-ige antibodies and their use in anaphylaxis

Disclosed is a method for detecting an anti-drug antibody of IgE isotype that binds to a therapeutic anti-IgE antibody in a sample, comprising the steps of: (a) contacting a sample that may contain the anti-drug antibody with a mutant therapeutic antibody comprising one, two, three, four, five, or six amino acid mutations in the CDR sequences of the heavy and/or light chain of the therapeutic anti-IgE antibody, wherein the relative binding affinity of the mutant therapeutic antibody to human IgE is about 10% or less of the relative binding affinity of the therapeutic anti-IgE antibody to the human IgE; and (b) detecting binding of the anti-drug antibody to the mutant therapeutic antibody. Also disclosed is a kit for carrying out the above described method.