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.