Regulatory constraints in the generation and differentiation of IgE-expressing B cells

B cells expressing antibodies of the immunoglobulin E (IgE) isotype are rare, yet are heavily implicated in the pathogenesis of allergies and asthma. This review discusses recent methodological advances that permit sensitive probing of IgE-expressing (IgE⁺) B cells in vivo and have accordingly clarified the basic behavior and fate of IgE⁺ B cells during immune responses in mouse models. IgE antibody secreting plasma cells can arise from extrafollicular foci, germinal centers, and memory B cells. However, compared to B cells expressing other isotypes, IgE⁺ B cells are susceptible to multiple additional regulatory constraints that restrict the size of the IgE⁺ B cell pool at each stage, coordinately limiting the overall magnitude, affinity, and duration of the IgE antibody response.