Recently, studies by Jönsson suggested a novel alternative pathway in which neutrophils, activated via IgG contributed to systemic anaphylactic shock in mice as well [7].In our experiments, peanut-induced systemic anaphylaxis in C57BL/6 mice was shown to be entirely dependent on FcRγ and mast cells and partially dependent on PAF, platelets and monocytes/macrophages. This evidence concerns the gene PCLAF and Shock.