The importance of molecular studies in the diagnosis and monitoring of IgE-mediated cow's milk protein allergy in children: a pilot study.

Introduction: Cow's milk protein allergy (CMPA) affects up to 3% of the paediatric population. The most reliable diagnostic tool for CMPA is oral food challenge (OFC), which may carry risks for the patient. Aim: The aim of this study was to assess the usefulness of molecular testing for CMPA in diagnosing and evaluating tolerance acquisition in children with IgE-dependent allergy to this food. Material and methods: The study included 49 children (average age: 2 years and 8 months) with an IgE-dependent allergy CMPA. Data from medical history was analysed at two time points, including the assessment of allergen-specific IgE (asIgE) against cow's milk extract, α-lactalbumin, β-lactoglobulin, casein, and bovine serum albumin, measured using the fluoroimmunoenzymatic assay (FEIA). Additionally, results from OFC with baked and raw cow's milk were included. Results: For both baked and raw milk allergies, the best marker for clinical reactivity was the asIgE level for casein (≥ 7.01 kU/l; AUC = 0.869 for baked milk and ≥ 5.96 kU/l; AUC = 0.710 for raw milk). The optimal asIgE level, measured by FEIA, to assess the risk of anaphylaxis during the OFC with baked milk was ≥ 7.01 kU/l for casein (AUC = 0.60). The marker for anaphylaxis in the course of OFC with raw milk was asIgE for β-lactoglobulin ≥ 1.71 kU/l (AUC = 0.724). For monitoring CMPA, the most useful markers were asIgE for casein, milk extract, and both α-lactalbumin and β-lactoglobulin. Conlusions: For both baked and raw milk allergies, the best marker for clinical reactivity remains casein. Testing for cow's milk allergens using solely molecular methods is insufficient for diagnosing and monitoring CMPA.