The usefulness of casein-specific IgE and IgG4 antibodies in cow's milk allergic children
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
Clinical and Molecular Allergy 2012, 10:1 doi:10.1186/1476-7961-10-1Published: 2 January 2012
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.
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).
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.
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.