Donor WT1 peptide vaccination enhances graft-versus-tumor activity of the minor-mismatch C3H.SW→C57BL/6 bone marrow transplant model. (A) Vaccination and bone marrow transplant scheme was the same as in Figure 3A except that C3H.SW donors were used instead of LP/J donors. (B) Survival after vaccination with WT1 peptide and IFA (closed symbols) compared with IFA alone (open symbols) after syngeneic, concomitant observed controls (C57BL/6→C57BL/6, ▾ vs ▿, P < .001) or allogeneic (C3H.SW→C57BL/6, ● vs ○, P < .001; ▾ vs ●, P < .001) bone marrow and splenocyte transplantation (n = 10 mice per group). Some recipients were given a vaccine boost (C3H.SW→C57BL/6, ▴ vs ●, P = .265). (C) PBLs were isolated from C57BL/6 controls or 28 days after transplantation of C57BL/6 recipients with C3H.SW donor cells and assayed for staining for donor marker Ly9.1 versus TCRβ or versus B220. Left panels show representative normal control C57BL/6 mice and right panels show C57BL/6 recipients of C3H.SW donor transplants. (D) Plots are mean percentages of donor type cells among T cells of 5 mice per group. (E-F) Representative images of 4 mice per group and bioluminescence intensity (mean ± SE for groups starting with 10 mice per group) of albino C57BL/6 recipients at 3, 12, 24, and 36 days after bone marrow and splenocyte transplantation from IFA alone vaccinated (○) or WT1 peptide + IFA vaccinated C3H.SW donors with (▴) or without vaccine “boost” (●; ○ vs ● at day 24, P < .001). Blank images represent death of recipients.