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Open Access Highly Accessed Research

The usefulness of casein-specific IgE and IgG4 antibodies in cow's milk allergic children

Komei Ito1*, Masaki Futamura12, Robert Movérare34, Akira Tanaka5, Tsutomu Kawabe6, Tatsuo Sakamoto7 and Magnus P Borres38

Author Affiliations

1 Department of Allergy, Aichi Children's Health and Medical Center, Obu, Japan

2 Division of Allergy, National Center for Child Health and Development, Tokyo, Japan

3 Phadia AB (now Thermo Fisher Scientific), Uppsala, Sweden

4 Department of Medical Sciences, Respiratory Medicine and Allergology, Uppsala University, Uppsala, Sweden

5 Phadia KK (now Thermo Fisher Scientific), Tokyo, Japan

6 Department of Medical Technology, Nagoya University School of Health Sciences, Nagoya, Japan

7 Department of Hygiene, Yamaguchi University Graduate School of Medicine, Ube, Japan

8 Department of Pediatrics, Sahlgrenska Academy of Göteborg University, Göteborg, Sweden

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Clinical and Molecular Allergy 2012, 10:1  doi:10.1186/1476-7961-10-1

Published: 2 January 2012

Abstract

Background

Cow's milk allergy is one of the most common food allergies among younger children. We investigated IgE antibodies to milk, and IgE and IgG4 antibodies to casein, α-lactalbumin and β-lactoglobulin in cow's milk allergic (CMA) and non-allergic (non-CMA) children in order to study their clinical usefulness.

Methods

Eighty-three children with suspected milk allergy (median age: 3.5 years, range: 0.8-15.8 years) were diagnosed as CMA (n = 61) or non-CMA (n = 22) based on an open milk challenge or convincing clinical history. Their serum concentrations of allergen-specific (s) IgE and IgG4 antibodies were measured using ImmunoCAP®. For the sIgG4 analysis, 28 atopic and 31 non-atopic control children were additionally included (all non-milk sensitized).

Results

The CMA group had significantly higher levels of milk-, casein- and β-lactoglobulin-sIgE antibodies as compared to the non-CMA group. The casein test showed the best discriminating performance with a clinical decision point of 6.6 kUA/L corresponding to 100% specificity. All but one of the CMA children aged > 5 years had casein-sIgE levels > 6.6 kUA/L. The non-CMA group had significantly higher sIgG4 levels against all three milk allergens compared to the CMA group. This was most pronounced for casein-sIgG4 in non-CMA children without history of previous milk allergy. These children had significantly higher casein-sIgG4 levels compared to any other group, including the non-milk sensitized control children.

Conclusions

High levels of casein-sIgE antibodies are strongly associated with milk allergy in children and might be associated with prolonged allergy. Elevated casein-sIgG4 levels in milk-sensitized individuals on normal diet indicate a modified Th2 response. However, the protective role of IgG4 antibodies in milk allergy is unclear.

Keywords:
casein; cow's milk allergy; IgE; IgG4; ImmunoCAP