GVHD T cells that have undergone homeostatic expansion in secondary hosts are capable of responding to third-party alloantigens. (A) Spleen cells (adjusted to yield 1 × 105 T cells/well) from either normal B6 (□) or from secondary B6→AKR chimeras that had been transplanted 70 days earlier with T cells from primary B6→AKR GVHD animals (■) were cultured in triplicate wells in the absence (−STIM) or presence of third-party Balb/c CD11c+ dendritic stimulator cells (+STIM) (5 × 104) in a standard MLC for 5 days. Data are presented as the mean ± SEM. (B-C) Lethally irradiated (1100 cGy) AKR mice were first transplanted with Rag-1 BM (5 × 106) and splenocytes that were obtained 22 days after BMT from donor T-cell–engrafted primary B6→AKR chimeras. Spleen cells (adjusted to yield a T-cell dose of 5 × 105/mouse) were pooled from these mice 70 days after BMT and transplanted along with Rag-1 BM (6 × 106) into lethally irradiated (900 cGy) Balb/c animals (n = 13; ○). Control mice received either Rag-1 BM alone (n = 6; □) or Rag-1 BM plus spleen cells (adjusted to yield a T-cell dose of 5 × 105/mouse) from normal B6 animals (n = 13; ●). Actual survival (B) and serial weight curves ± 1 SD (C) for each cohort are depicted. Data are cumulative results from 2 experiments.
