The severity of an allergic reaction may not only depend on the type of allergen, IgE levels, cytokine exposure, and the microenvironment but also on the total number of effector cells involved in the reaction.12, 13, 14 Conditions with high numbers of BA and MC include chronic inflammation, certain neoplastic states, and specific neoplasms, including basophilic leukemias and mastocytosis. Here, IGHE is linked to mastocytosis.