Indirect presentation of DST antigens by host APCs mediates hyporesponsiveness of TEa Tg T cells and long-term allograft survival. TEa Tg T cells (1 × 10⁶) were adoptively transferred into C57BL/6 RAG^–/– recipients (n = 15 per group) in the presence of CB6F₁ skin alone or together with CB6F₁ DST or T-cell–depleted Balb/c DST to assess indirect presentation. A separate group of mice received TEa cells and syngeneic skin as a negative control. All the groups received injections of αCD154 or control H-Ig 3 times per week. (A) After 7 days, 4 mice per group were killed and cells were harvest from LNs. The same number of TEa Tg T cells were plated with irradiated CB6F₁ spleen cells to verify their ability to respond to in vitro restimulation by measuring ³H-thymidine incorporation. The remainder of the mice were followed for transplant rejection kinetics over time in presence of (B) control H-Ig or (C) αCD154.