CD4⁺ T cells, B cells, and IL-4 are required for DTA-1–induced anaphylaxis. (A) RAG^−/− mice, (B) TCRβ-deficient mice, (C) MHC class I–deficient mice, (D) MHC class II–deficient mice, and (E) µMT mice were injected with 1 mg DTA-1 on days 0, 4, and 11. Rectal temperatures of mice were monitored for 1 hour following the final injection. (F) C57BL/6J mice were treated with 1 mg DTA-1 on days 0, 4, and 11. Concurrently with the day 0 injection, mice also received 0.5 mg anti-IL-4 (clone 11B11) or isotype control (rat IgG1, clone HRPN). Rectal temperatures were monitored following the day –11 dose of DTA-1. Lines in the graphs represent the mean of each group of mice. The data are representative of 2 independent experiments (n = 5 mice per group). *P < .05; **P < .0001 by unpaired 2-tailed Student t test.