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MRT Laboratories, Inc.

50 Johnson Ave.
Hackensack, NJ 07601
201-342-5400
800-631-1379
FAX 201-342-1123
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Allergen Specific IgG4 (ELISA)

...IgG4

The laboratory confirming diagnosis of food intolerance has been complicated by the fact that these adverse reactions can be caused by several immunological mechanisms. Those untoward reactions to foods mediated by an IgE antibody mechanism have been validated by in-vitro methods for over 20 years. Since many unfavorable reactions to food are not mediated by an IgE mechanism, many physicians have been measuring specific IgG antibodies in an attempt to identify offending foods. The validity of these results has been questioned. In addition, these IgG tests have been shown to lack a range of reactivity to be of significant clinical value. The range of non-specific binding to the highest level of specific binding is so narrow (5-6x background) that attempts to distinguish between classes of reactivity are meaningless. These problems have been overcome by the development of in-vitro tests for the measurement allergen-specific IgG4 antibody. Such tests have the potential to serve a role in the diagnosis of dietary antigens in atopic dermatitis and managementof food intolerant patients. Merritt et al observed high levels of IgG4 antibodies to a number of foods, including egg white, milk, codfish and peanut in atopic eczema patients. The measurement of allergen-specific IgG4 has also been reported as a marker of an immune response toward milk and egg in asthma, celiac disease and other conditions. It has recently been reported that shrimp food challenge-positive individuals demonstrated a trend toward higher shrimp-specific IgG4 levels than the rest of shrimp sensitive individuals. In addition, subjects with high levels of shrimp-specific IgE and a negative challenge had the lowest shrimp-specific IgG4 in the negative- challenge group. It has been speculated that IgG4 may have a provocative role in food-induced allergic reactions in contrast to its protective role in venom and respiratory allergy.

MRT Labs has developed a new quantitative IgG4 in-vitro assay (the asIgG4 test) with a range of reactivity comparable to the Modified RAST IgE test which has been so useful in the evaluation of allergen-specific IgE disorders. The asIgG4 test can be ordered for individual foods or in panels of ten. Over 100 foods are available for testing. For more detailed information please contact us directly at MRT Laboratories.