IGHE and anaphylaxis: Although anaphylaxis is classically attributed to an IgE-mediated mast cell-dependent paradigm of allergic reactivity, the same systemic symptoms can be reproduced experimentally in mice by the transfer of specific IgG antibodies and allergen, of preformed immune complexes (passive systemic anaphylaxis, PSA), or by repeated immunization with an antigen prior to challenge (active systemic anaphylaxis, ASA).