Anti-CD2 + 48 MoAb is ineffective in preventing GVHD-induced lethality by donor CD8⁺ T cells infused into sublethally irradiated recipients. Sublethally irradiated bm1 (A) or bm12 (B) recipients were administered the indicated number of highly purified CD8⁺ or CD4⁺B6 LN cells as shown in parentheses on day 0. Mice received either irrelevant IgG or CD2 + 48 MoAb (300 μg/dose each) IP twice weekly from days −1 through +21 posttransfer. On the x-axis are the days posttransfer and on the y-axis is the proportion of mice surviving. The survival data are plotted. Results from two (A, n = 16/group) or three (B, n = 24/group) replicate experiments with similar results are pooled. Mice administered CD2 + 48 MoAb had a significantly (P = .002) higher actuarial survival rate as compared with controls.