IPA exposure did not reduce T-cell responses to IPAs. (A) CD4⁺ T cells isolated from spleens of IPA-exposed B6 and control B6 mice were cultured with B6D2F1 DCs for 72 hours, and the cells were pulsed with ³[H]thymidine. Proliferation is shown as mean ± SD. (B) Lethally irradiated B6D2F1 mice received transplants with 5 × 10⁶ TCD BM from control B6 mice together with 2 × 10⁶ T cells from either an IPA-exposed (IPA×1), an IPA–double-exposed (IPA×2), or a control B6 donor. Survival rates of recipients of syngeneic BMT (•, n = 6), allogeneic BMT from a control donor (○, n = 11), allogeneic BMT from an IPA×1 donor (•, n = 11), and allogeneic BMT from an IPA×2 donor (▪, n = 11) are shown. Data from 2 similar experiments were combined.