Although it is thought that B cells switched to IgE are very poorly recruited to the memory compartment of the immune system [63,65], it has recently been shown in murine models of peanut allergy that a memory response is crucial to re-activation of clinical IgE reactivity, with IL-4 from T cells driving IgG memory B cells to switch and mature into IgE plasmablasts [66]. The gene discussed is IGHE; the disease is peanut allergic reaction.