αCD154/DST treatment reduces the functional activity of TEa Tg T cells in vivo and in vitro. C57BL/6 RAG KO mice were injected with TEa Tg T cells with or without CB6F₁ spleen cells, and in the presence or absence of a CB6F₁ skin graft on day 0. Anti-CD154 or control H-Ig was injected 3 times per week. On day 7, LNs were harvested and TEa Tg T cells were positively sorted. (A) Purified TEa Tg T cells were transferred to naive C57BL/6 RAG KO recipients together with a CB6F₁ skin graft. Graft rejection was monitored as described previously (▾ represents naive TEa Tg T cells [n = 10]; ▪, DST-exposed TEa Tg T cells [n = 9]; •, DST + αCD154–exposed TEa Tg T cells [n = 8]). Data were pooled from 2 separate experiments. Also, purified effector TEa Tg T cells were plated in vitro with irradiated CB6F₁ stimulator cells as described in “Materials and methods.” Then, 72 hours later, cells and supernatants were harvested for quantification of (B) ³H-thymidine incorporation, (C) IL-2 production, and (D) IFN-γ production.