Donor T-cell precursor frequency is critical for induction of GVHD. Rachel T cells were transplanted along with TCD BM from B6♀ donors into lethally irradiated syngeneic B6♀ or allogeneic B♂ animals. The recipients were monitored for (A) survival and GVHD score. (B) Histopathology scores for liver and GI tract. (C) Skin H&E (left) and score (right). Data are from 1 of 3 similar experiments.