Food antigens drive spontaneous IgE elevation in the absence of commensal microbiota

Immunoglobulin E (IgE), a key mediator in allergic diseases, is spontaneously elevated in mice with disrupted commensal microbiota such as germ-free (GF) and antibiotics-treated mice. However, the underlying mechanisms for aberrant IgE elevation are still unclear. Here, we demonstrate that food antigens drive spontaneous IgE elevation in GF and antibiotics-treated mice by generating T helper 2 (T(H)2)–skewed T follicular helper (T(FH)) cells in gut-associated lymphoid tissues (GALTs). In these mice, depriving contact with food antigens results in defective IgE elevation as well as impaired generation of T(FH) cells and IgE-producing cells in GALT. Food antigen–driven T(FH) cells in GF mice are mostly generated in early life, especially during the weaning period. We also reveal that food antigen–driven T(FH) cells in GF mice are actively depleted by colonization with commensal microbiota. Thus, our findings provide a possible explanation for why the perturbation of commensal microbiota in early life increases the occurrence of allergic diseases.