Figure 1. Calpain activity is required for FcεRI-dependent mast cell degranulation both in vitro and in vivo.
A–E, Wild-type BMMCs were sensitized with anti-TNP IgE and treated with various calpain inhibitors for 30 min, and then stimulated with TNP-BSA for 20 min. Mast cell degranulation was measured by β-hexosaminidase release. Calpain inhibitor III (A), V (B), IX (C), XI (D), and XII (E) significantly inhibited mast cell degranulation in a dose-dependent manner. F, C57BL/6 mice were sensitized with anti-DNP IgE for 24 h by intradermal injection, followed by intraperitoneal injection with 500 μl of 5 mM calpain inhibitor III for 1 hour. Mice were then challenged by i.v. injection of DNP-BSA in Evans blue dye solution. Thirty minutes later, ear tissue was collected and Evans blue dye was extracted to assess vascular permeability by spectrophotometry. n = 4 (A, C, D, and E) or 5 (B) cultures of BMMCs, or n = 6 mice (F). Data are means ± SEM, *p< 0.05, **p < 0.01.