Naive T cells from CD18^−/− donors have diminished ability to induce GVHD. Spleen and lymph nodes were harvested from WT or CD18^−/− donors, and CD25⁻CD62L⁺ naive T cells were purified with magnetic beads as described in “Methods.” CD25 and CD62L expression were shown on WT or CD18^−/− CD4⁺ and CD8⁺ T cells before (A) and after (B) purification. Numbers in the panels indicate the percentages of cells in the gate as shown among total splenocytes (left panels), CD4⁺ cells (middle panels), or CD8⁺ cells (right panels). Lethally irradiated BALB/c mice were given intravenous injections of 5 × 10⁶ TCD-BM cells alone or with naive T cells from WT or CD18^−/− B6 donors. (C) Survival of recipients given TCD BM cells alone (n = 12) or with WT or CD18^−/− naive T cells at 0.5 × 10⁶ (0.5 M) or 2 × 10⁶ (2 M) per mouse. The recipients with donor T cells at 2 M were 12 mice per group, and there were 6 mice per group at 0.5 M. (D) Mean changes in percentage of body weights for the recipients as in panel C.