Cutting Edge: Helminth Infection Induces IgE in the Absence of μ- or δ-Chain Expression

Infections with helminth parasites are associated with an IgE isotype switch and high serum IgE concentrations. IgE is rapidly bound by the high affinity IgE receptor (Fc epsilon RI), thereby sensitizing Fc epsilon RI-bearing basophils and mast cells for. IgE-inducible effector functions such as IL-4 production. The development of Absecreting B cells is dependent on IgM and consequently, mu MT mice, which lack surface IgM, are considered devoid of Abs. In this study we report the unexpected finding that C57BL/6 mu MT mice generate robust IgE responses upon infection with three distinct helminth parasites, Heligmosomoides polygyrus, Trichuris muris, and Schistosoma mansoni. IgE is produced despite an apparent block in B cell development and licenses basophils for IgE-induced IL-4 production. Our findings reveal the existence of an evolutionarily conserved, IgM-independent pathway for the production of IgE upon infection with helminth parasites. The Journal of Immunology, 2008, 181: 6697-6701.