Abstract: This invention particularly discloses an improved immunoassay method for the sensitive and specific detection of food specific human IgG4 antibodies. A sample diluent comprising a chaotrophic agent is used to reduce the occurrence of nonspecific antibody-dietary antigen interactions. To reduce competition between IgE and IgG4 antibodies for specific epitopes on dietary antigens a heat denaturing step is included to inactivate IgE antibodies. Finally, a signal amplification step is included in the assay to reduce the amount of sample required to perform the assay.