Oral cow milk challenge abolishes antigen-specific interferon-γ production in the peripheral blood of children with atopic dermatitis and cow milk allergy

Background A major feature of atopic dermatitis (AD) is the propensity to generate IgE to environmental antigens. Despite extensive information on IgE dysregulation in AD, the nature of immune responses to ingested allergens is poorly characterized. Objective To determine the clinical and immunological responses to food in AD patients. Methods To characterize the type and timing of clinical reactions to oral cow milk, 83 AD patients aged 2 to 60 months were subjected to double-blind placebo-controlled food challenge (DBPCFC). IFN-γ and IL-4 production by their peripheral blood mononuclear cells (PBMC) was determined before and after DBPCFC. Results Of 50 patients positive to DBPCFC, 46% manifested exanthematous-type immediate-onset reactions and 54% eczematous-type late-onset reactions. In either group, the production of lL-4 and IFN-γ by Concanavalin A-stimulated FBMC was comparable before and after DBPCFC. For immediate-reacting patients, the median IFN-γ production by milk-stimulated PBMC was 11.5 (4.2–17.2) pg/mL as against 2.3 (0.2–5.7) pg/mL by unstimulated PBMC, P = 0.0008 before DBPCFC, and 4.6 (2.8–10.3) pg/mL vs 4.2 (1.7–9.0) pg/mL, P = 0.40, correspondingly after DBPCFC. Conclusion Before DBPCFC, immediate-reacting but not late-reacting patients were found to be capable of allergen-specific IFN-γ production in vitro, indicating the heterogeneity in AD patients. After DBPCFC, the IFN-γ generation abolished, indicating the effect of oral allergen exposure on IFN-γ-producing responses of AD patients.