This chapter first provides a high level overview of allergic disease. There follows a review of allergens and their effects at the cellular level in allergic reactions. A list of common allergy sources, the specific allergens associated with them and some of their properties is provided. Diagnosis and therapy principles are summarized. Total serum IgE is reviewed as a key analyte, with the clinical applications, reference intervals (for background information only), limitations, assay technology, desirable assay performance characteristics, and sample types. Then in the remainder of the chapter, allergen-specific IgE antibodies are reviewed, and their use in identifying the allergen(s) involved for each patient. Assay design and general characteristics are described, with the specific assay requirements for allergen antibody tests. Standardization, calibration, and quality control and quality assurance, are covered. The concept of component-resolved diagnostics is explained and microarrays for allergen testing reviewed.

Marcos Alcocer is currently Associated Professor at the School of Biosciences, University of Nottingham, UK. His group is mainly interested in understanding the molecular mechanisms behind the immune recognition by susceptible individuals of common proteins as (food) allergens. The main molecular models used are nut proteins. His group is also involved in developing new tools for the clinical diagnose of allergy and safety of vaccines, in particular, the development of a comprehensive basophil microarray platform.

This chapter also contains some material contributed to the first edition of The Immunoassay Handbook by Dr. Lars Yman, formerly Associate Professor and Research Director, Pharmacia Diagnostics AB, Uppsala, Sweden.

Allergy, antibody, hypersensitivity, anaphylactic, sensitization, allergen, atopic, immunoglobulin E, anti-immunoglobulin E, Phadiatop^®, radioallergosorbent test (RAST), component-resolved diagnostics.

The test technology described in the chapter, originally developed by Pharmacia, is described on a Thermo Scientific website for the UK at www.phadia.com/en-GB/5/Autoimmunity-Tests/Test-Principle-ImmunoCAP-Specific-IgA/, and also at www.phadia.com/en-GB/5/Products/.