Figure 2.

IgE-mediated systemic anaphylaxis in FcγRIIB^−/− mice. (A) Changes in rectal temperature during IgE-mediated systemic anaphylaxis. 29 wild-type (WT; □) and 24 FcγRIIB^−/− animals (▪) received 20 μg i.v. anti-TNP IgE. All of the animals received 1.0 mg i.v. TNP₄-OVA 24 h later. Three additional wild-type (○) as well as FcγRIIB^−/− mice (•) received IgE and then OVA. The monitoring of rectal temperature was started at the time of antigen injection. Data are shown as mean ± SD. **P < 0.01. (B) Changes in heart rate during IgE-mediated systemic anaphylaxis in three FcγRIIB^−/− (▪) and three wild-type (□) mice. The induction protocols were the same as in A. As controls, three wild-type mice (○) received OVA. Note the transient rise maximizing ∼1 min after TNP-OVA injection in wild-type mice and the gradual decrease during the 25 min after induction, in contrast to the changes in FcγRIIB^−/− mice, showing no transient rise and continuous decrease in heart rate. *P < 0.05; **P < 0.01, compared with wild-type mice. (C) Increased hemorrhage in ileum villi during IgE-mediated systemic anaphylaxis in FcγRIIB^−/− mice. 1 h after the anaphylaxis induction, mice were killed, and ileum samples were observed under light microscopy. Hemorrhage in tips of microvilli was evident in FcγRIIB^−/− mice. Magnification 40.