Direct detection of IgE-switched B cells in an IgE-GFP reporter mouse reveals a germinal center pathway for the generation of IgE memory B cells and plasma cells

IgE antibodies are pathogenic in asthma and allergic diseases, but the in vivo biology of IgE cells is poorly understood, largely due to their low frequency and a lack of good reagents to detect them specifically. It has been proposed that IgE cells develop through a germinal center IgG1 intermediate and that IgE memory resides in the IgG1 memory B cell compartment. Here we have utilized a recently generated IgE-GFP reporter mouse that enables the direct detection of IgE-switched cells to assess in vivo IgE responses. In contrast to the IgG1-centered model of IgE switching and memory, we find that IgE cells develop through a germinal center IgE intermediate to form IgE memory B cells and plasma cells. Moreover, IgE memory B cells, as opposed to IgG1 memory B cells, constitute cellular IgE memory and respond quickly upon rechallenge to produce serum IgE. Our studies provide a new model for the in vivo biology of IgE switching and memory.