Type 2 IgG Memory B Cells and Long-Lived IgE Plasma Cells in the Persistence of Allergy

IgE antibodies mediate allergic reactions through their ability to bind to high affinity receptors on mast cells and basophils, triggering cell activation and degranulation upon crosslinking by allergens. The differentiation of IgE-producing cells is unique, as there is a paucity of IgE memory B cells and most IgE-expressing cells are plasma cells. High affinity IgE, however, is generated through sequential class switching from affinity-matured non-IgE memory B cells. Emerging studies have uncovered key features of the IgE response that are relevant to allergy development and persistence, including the existence of allergen-specific high affinity type 2 IgG memory cells that are poised to switch to IgE, and long-lived IgE plasma cells that reside in the bone marrow and secondary lymphoid organs. Here, we review how these processes sustain IgE memory and long-term allergic sensitization despite the short lifespan of circulating IgE.