ORAL COW MILK CHALLENGE ABOLISHES ANTIGEN-SPECIFIC INTERFERON-GAMMA 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 informat ion on IgE dysregulation in AD, the nature of immune responses to inge sted allergens is poorly characterized. Objective To determine the cli nical and immunological responses to food in AD patients. Methods To c haracterize the type and timing of clinical reactions to oral cow milk , 83 AD patients aged 2 to 60 months were subjected to double-blind pl acebo-controlled food challenge (DBPCFC). IFN-gamma and IL-4 productio n by their peripheral blood mononuclear cells (PBMC) was determined be fore and after DBPCFC. Results Of 50 patients positive to DBPCFC, 46% manifested exanthematous-type immediate-onset reactions and 54% eczema tous-type late-onset reactions. In either group, the production of IL- 4 and IFN-gamma by Concanavalin A-stimulated PBMC was comparable befor e and after DBPCFC. For immediate-reacting patients, the median IFN-ga mma production by milk-stimulated PBMC was 11.5 (4.2-17.2) pg/mL as ag ainst 2.3 (0.2-5.7) pg/mL by unstimulated PBMC, P = 0.0008 before DBPC FC, and 4.6 (2.8-10.3) pg/mL vs 4.2 (1.7-9.0) pg/mL, P = 0.40, corresp ondingly after DBPCFC. Conclusion Before DBPCFC, immediate-reacting bu t not late-reacting patients were found to be capable of allergen-spec ific IFN-gamma production in vitro, indicating the heterogeneity in AD patients. After DBPCFC, the IFN-gamma generation abolished, indicatin g the effect of oral allergen exposure on IFN-gamma-producing response s of AD patients.