Usefulness of casein specific IgE and IgG antibodies to immediate type cow's milk allergy

ABSTRACT

PURPOSE: Cow's milk-specific IgE (CM-IgE) has been proposed as one of the valuable markers for diagnosis of clinical cow's milk (CM) allergy. In this study, we evaluated the additional usefulness of casein-specific IgE (casein-IgE) and IgG (casein-IgG) for the diagnosis of clinical CM allergy. METHODS: Fifty-eight subjects, aged from 3 months to 154 months, were enrolled. Thirty-four patients showed immediate-type of clinical CM allergy, and 24 patients were atopic controls. The serum levels of CM-IgE, casein-IgE, and casein-IgG were measured. Patients were divided into 2 groups those aged under 12 months and those aged 12 months or over. The diagnostic values of each antibody were analyzed and compared using the Mann-Whitney U-test and receiver operating characteristic curves. RESULTS: CM allergy had significantly higher levels of CM-IgE and casein-IgE, and lower levels of casein-IgG/IgE ratio when compared to atopic controls in both age groups (P<0.05). CM-IgE and casein-IgE were shown to be better predictive markers for immediate-type CM allergy in patients under 12 months, while casein-IgG/IgE ratio was a more useful marker in those aged 12 months or over. Considering 100% positive predictive values, cutoff points were 1.04 kU/L for CM-IgE, 0.11 kU/L for casein-IgE, 19.5 for casein-IgG/IgE ratio in patients aged under 12 months, and 7.1 kU/L for CM-IgE, 1.41 kU/L for casein-IgE, 12.51 for casein-IgG/IgE ratio in those aged 12 months or over. CONCLUSION: CM-IgE, casein-IgE, and casein-IgG/IgE ratio are useful markers for predicting immediate-type CM allergy. Further studies are needed on diagnostic decision points for CM allergy using combination of cutoff values of these 3 markers.