Purified central memory T cells do not cause GVHD. Sorted T-cell subsets were transplanted into lethally irradiated recipients, along with T-cell–depleted BM cells. Mice were monitored for the development of GVHD. Data were pooled from 3 independent experiments. (A) Survival. P < .05, T_CM or T_EM versus naive. (B) Weight curve. P not significant, TCD BM only versus T_EM or T_CM.