S. aureus exposure during cutaneous antigen sensitization causes basophil- and interleukin-4-dependent exaggerated food anaphylaxis.

The mechanism of the association of S. aureus skin colonization with food allergy in atopic dermatitis (AD) is unknown. Interleukin-4 (IL-4) plays an important role in food allergy. We found elevated serum IL-4 concentrations in AD patients with S. aureus skin colonization and food allergy. Using an AD mouse model, we demonstrated that epicutaneous application of antigen together with superantigen-producing S. aureus, or staphylococcal enterotoxin B (SEB), caused a heightened systemic antigen-specific T helper-2 (Th2) response and elevated serum IL-4 concentrations. T cell-derived IL-4 acted on intestinal epithelial cells to enhance intestinal permeability and anaphylaxis to enteral antigen challenge. CD40-dependent SEB binding to keratinocytes triggered IL-33 release, which caused T cells to produce IL-3 that elicited a basophil influx in skin-draining lymph nodes (dLNs). Basophil-derived IL-4 augmented Th2 cell polarization by antigen-bearing dendritic cells from skin dLNs. These results suggest therapeutic interventions that might attenuate food allergy in AD patients.