Memory cells constitutively expressing CD62L do not cause severe GVHD. (A) Sorting strategy. MACs-purified CD4⁺CD25⁻ cells (left panel) were subsequently sorted into T_N and T_EM fractions based on CD45RB and CD44 expression according to the indicated gates; postsort analysis in rightmost panels. Sort of LΔP cells is shown; sorting parameters for WT and LΔP cells were identical. (B-D) On day 0, BALB/c recipients received 800 cGy and 10⁷ BM cells from CD45.1 B6 donors with or without 3 × 10⁵ naive or memory cells from WT B6 or LΔP (B6) donors. (B) Weight curve. †P < .05 for BM controls versus WT naive or LΔP naive for all days 10 and later; @P < .05 for BM controls versus LΔP memory for all days 20 and later. *P < .05 for BM controls versus WT memory at day 23 only. (C) Survival curve. †P < .01 for BM controls versus WT naive or versus LΔP naive. (D) Liver, colon, and skin histopathology. P < .05 for BM controls versus WT naive or LΔP naive for all analyses; NS indicates not significant for WT memory versus LΔP memory.