Laboratory tests

Laboratory tests fall into two groups. The first are those that identify substances present independent of a recent or concurrent IgE-mediated reaction. The most widely used tests are based upon the serum assays of specific IgE. More direct evidence of the potential for a reaction can be obtained by challenging in vitro suspensions of extracted leucocytes (white blood cells) with allergen. Other, non-IgE antibodies can be assayed using similar techniques to those used for the detection of IgE molecules, but their diagnostic relevance is less clear. There are tests that identify cells rather than antibodies. Reports include the detection of specific peripheral mononuclear cells (white blood cells which circulate in the body). This process remains confined to the research arena.

The second group of tests includes those that are dependent upon a recent or concurrent reaction. At present these too are confined to the research arena. They may prove useful in the future in the retrospective diagnosis of reactions to food allergens. On the whole they do not give information about which specific allergen produced the reaction but only supply supportive evidence of a recent immunologically mediated reaction. They include measurements of various cell mediators.

Double-blind placebo-controlled food challenges remain the 'gold standard' in the diagnosis of food allergies, but in vitro tests can supplement this.

Nearly all current diagnostic knowledge lies within the area of Type I, IgE-mediated mechanisms of food allergy. This is the only conclusively proven aetiology of food allergy.

Food Allergies

Food Allergies

Peanuts can leave you breathless. Cat dander can lead to itchy eyes, a stuffy nose, coughing and sneezing. And most of us have suffered through those seasonal allergies with horrible pollen counts. Learn more...

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