Basophil activation through ASGM1 stimulation triggers PAF release and anaphylaxis-like shock in mice

Basophils have been shown to contribute to anaphylaxis through either an IgE-FcεRI-dependent pathway or an IgG-FcγR pathway. However, it remains largely unclear whether basophils can be activated to promote anaphylaxis via a non-FcR pathway as well. The glycolipid receptor ASGM1 (Asialoganglioside gangliotetraosylceramide), which has an exposed GalNAcβ1-4Gal moiety and serves as a receptor for pathogen associated molecular patterns such as flagellin, was recently found to be expressed on basophils. Here, we demonstrate that stimulation of basophils with anti-ASGM1 antibodies promotes platelet-activating factor (PAF) secretion in vitro and in vivo. Moreover, we found that ASGM1 stimulation triggers basophil- and PAF-dependent anaphylactic shock in pertussis toxin (PTX)-pretreated mice. Thus, ASGM1 has a crucial role in basophil activation and basophil-mediated anaphylaxis-like shock in mice, especially when the vascular permeability is increased by PTX treatment. Our findings describe a novel anaphylaxis-associated pathway that is antigen-, antibody-, and FcR-independent.