Threshold dose of cow's milk in sensitization to casein higher than those of casein and β-lactoglobulin in children with cow's milk allergy.

Background: Recent treatment for food allergies involves the intake of allergy-causing foods at doses lower than the threshold dose determined by the oral food challenge (OFC). For a more successful treatment, it is necessary to identify a biomarker to establish safer doses of allergens in foods consumed at home.

Objective: In this study, we aim to investigate whether the pattern of sensitization to cow's milk (CM) is related to the threshold dose of CM.

Methods: Fifty patients with sensitization to casein (casein-specific IgE titer ≥ 0.7 UA/ml) and who have undergone the CM OFC test from July 2013 to July 2015 were enrolled. They were examined for the presence or absence of sensitization to β-lactoglobulin (BLG) (BLG-specific IgE ≥ 0.7 UA/ml). They were divided into two groups, namely, the only-casein-specific IgE-positive (C) group, and both casein- and BLG-specific IgE-positive (C + B) group.

Results: The C group had 26 patients and the C + B group had 24. Both the CM- and casein-specific IgE titers were higher in the C + B group than in the C group. The positivity rates determined from OFC test results were 53.8 and 87.5%, and the threshold doses of CM were 88.7 and 31.1 ml in the C and C + B groups, respectively. In patients with low casein-specific IgE titers (≤ 10 UA/ml), the C + B group showed a significantly lower threshold dose of CM than the C group.

Conclusions: Our results suggest that children with CM allergy sensitized to casein alone have a higher threshold dose than those sensitized to both casein and BLG.