Since FPIES is a non-IgE-dependent allergy, the responses of antigen-specific T cells to the food allergen have been extensively studied6. However, although FPIES was associated with a significant increase in serum IL-17 family levels7—which is mainly secreted by Th17 cells and associated with neutrophil activation—cytometric analysis of peripheral blood has shown activation not of antigen-specific T cells but of systemic innate immune responses, such as increased neutrophil counts and activation of neutrophils, eosinophils, monocytes, and natural killer cells8. Similarly, transcriptome analysis of the whole peripheral blood showed high expression of genes related to innate immune responses in FPIES9.