Development of a Novel IgG1 Anaphylaxis Mouse Model with Uniquely Characteristic Skin Manifestations Induced Through the FcγRIII-Histamine Pathway

Background Studies of passive anaphylaxis, in which mouse immunoglobulin G (IgG) and its antigens are administered to mice, believe that platelet-activating factor (PAF) is more important than histamine and that basophils or macrophages are primarily involved. However, the full extent of IgG-dependent anaphylaxis is still unclear; that is, little agreement has been reached about the mechanism.Methods First, we established the novel model of IgG1 anaphylaxis induced by the intravenous administration of two types of IgG1 and a fluorescent dye-labeled antigen, as IgG1 immune complex in HR-1 hairless mice. Subsequently, pharmacological analysis was used to investigate the underlying mechanisms of IgG1 anaphylaxis in this established model.Results The novel IgG1 anaphylaxis model can induce the IgG-induced Anaphylaxis-dependent Spotted Distribution of fluorescently labeled Immune complexes in the Skin, named “G-ASDIS”. Moreover, this model was triggered primarily by the FcγRIII-dependent histamine release, which is different from the conventional model in which PAF was involved in the development of IgG1 anaphylaxis. Basophils in the circulation and mast cells in the skin may participate in the development of IgG1 anaphylaxis and increased G-ASDIS.Conclusion Our results propose that the novel axis, namely the FcγRIII-basophils and/or mast cell-histamine pathway, is important for IgG1 anaphylaxis. Further analysis of our model in addition to other models will lead to a broader analysis and understanding of the IgG1 anaphylaxis mechanism.