Runx1^P1N/P1N mice have normal mast-cell functions. (A) Analysis of passive cutaneous anaphylaxis reactions in WT and Runx1^P1N/P1N mice that received intradermal injections of IgE anti-DNP into the right ear pinnae and of saline into the left ear pinnae (control; none). After sensitization, mice were challenged intravenously with DNP-BSA. Data show means + SD of the extravasation of Evans blue into the ears. (B) Degranulation of WT and Runx1^P1N/P1N BMCMCs, assessed as the release of β-hexosaminidase. BMCMCs were sensitized with anti-DNP IgE and stimulated with the indicated concentrations of DNP-HSA (0, 6.25, 12.5, 25, 50, and 100 ng/mL). Data show the means + SD. (C) ELISA of IL-6 in BMCMCs from WT and Runx1^P1N/P1N mice sensitized with anti-DNP IgE and stimulated with DNP-HSA (10 ng/mL). nd indicates not detected. ***P < .0001; **P < .001; no asterisks, P > .05 relative to the corresponding WT mice. Data are from 1 of 3 independent experiments, each of which gave similar results.