Deletion of Pten in MCs causes increased anaphylactic responses and enhanced vascular permeability in vivo. (A) BMMCs and peritoneal MCs (PMCs; 5 × 10⁵ cells) were lysed in RIPA buffer. PTEN expression was determined by immunoblot with an antibody to PTEN. β-actin was used as loading control. One representative of 4 experiments is shown. (B) Pten^{wt/wtFcϵRIβCre+/wt} mice and Pten^{fl/flFcϵRIβCre+/wt} mice (age, 24 weeks) were passively sensitized with DNP-specific IgE and challenged 24 hours later with Ag (DNP-HSA) or pseudo-challenged with an equal volume of PBS. Anaphylactic reaction was measured by temperature change. Data are mean ± SEM of a minimum of 5 independent experiments. Statistical analysis was by 2-way ANOVA: ***P < .0001. Significant differences were observed between 25 and 45 minutes after challenge. (C) Pten^{wt/wtFcϵRIβCre+/+} mice and Pten^{fl/flFcϵRIβCre+/+} mice (age, 16 weeks) were inoculated intraperitoneally with K/BxN serum containing autoantibodies to glucose-6-phosphate isomerase (GPI) or with control serum (Ctrl). Joint swelling and clinical score were determined as described in “Anaphyloxis and arthritis models.” Data are mean ± SEM of a minimum of 8 mice. Statistical analysis was by a 2-way ANOVA: ***P < .0001. Significant differences were observed between 6 and 9 days after challenge. (D) Evans blue dye (200 μL) was injected intravenously in Pten^{wt/wtFcϵRIβCre+/+} mice and Pten^{fl/flFcϵRIβCre+/+} mice. Subsequently, they were challenged intradermally with 20 μL compound 48/80 (C48/80, 1.75 mg/mL) in PBS or as control with an equal volume of PBS. Vascular permeability was measured by extravasation of the dye into the ear tissue. Data are mean ± SEM from 10 mice. Statistical analysis was by unpaired 2-tailed Student t test: **P < .001.