IgG-mediated MC degranulation has not been studied in as great detail as IgE-dependent degranulation responses, but both contribute to vascular pathology in independent contexts, such as the Arthus reaction and anaphylaxis (Vaz and Ovary, 1968; Hazenbos et al., 1996; Sylvestre and Ravetch, 1996). This evidence concerns the gene IGHE and arthus reaction.