Although Th2 cells and TFH cells are generally considered to be the most relevant cell types for induction of IgE-CSR in B cells, it remains unclear to what extent innate IL-4/IL-13-expressing cell types contribute to this process, especially during secondary infection when basophils and mast cells can be rapidly activated to release large amounts of IL-4/IL-13. This evidence concerns the gene IGHE and infection.