IGHE and dermatitis: The differential responsiveness of M-Ext1 mice to irritant dermatitis caused by DNFB and IgE-mediated PCA prompted us to investigate the expression of Mrgprb2. Mrgprb2 is a receptor for basic secretagogues such as several irritants, peptides, and toxins, including S. aureus δ-toxin, that can activate MCs independently of FcεR1 (31, 32).