(A) C57BL/6 allograft recipients received 1.0 mg of either anti-CD8 Ab (clone 2.43, rat IgG2b) or rat IgG control Ab i.v. at day 0, 7, 14 and 21 post-transplant. Tracheal grafts were recovered on day 28, fixed and stained for histopathology. Bars represent mean + SEM OAD scores with p-values determined by rank sum test from two separate experiments with eight mice per group. (B) CD8+ T cells were isolated and purified from day 14 spleen, LN and lung of WT allograft recipients, CD154−/− allograft recipients or naïve WT mice. 5 × 106 CD8+ T cells from these groups were then adoptively transferred into fresh CD154−/− allograft recipients at d0, and allografts were assessed for OAD histopathology at day 28. Bars represent mean OAD scores ± SEM with p-values determined by rank sum test for paired samples and Kruskal–Wallis test for multiple groups. Results represent two separate experiments with 8–10 individual mice per group.