H4/H60-specific T cells are not required for GVHD independent of T-cell dose. H4/H60-specific T-cell–depleted splenocytes (2 × 106) or mock-depleted splenocytes from female B6 mice together with 5 × 106 T-cell–depleted BM cells were cotransferred into lethally irradiated male BALB.B recipients. Peripheral blood was obtained at indicated days after transfer, and the percentage of antigen-specific CD8+ T-cell responses ex vivo was determined for each individual mouse by intracellular IFNγ staining as described above. (A) Dot plots show H60-specific CD8+ T-cell responses on day 16 after transfer in peripheral blood of a representative mouse. Numbers in upper right quadrants reflect the percentage of IFNγ-producing CD8+ T cells of total CD8+ T cells. (B) Each ○ (restimulation with H60) or ⋄ (restimulation with OVA) represents 1 mouse; bars indicate averages. (C) Clinical signs of GVHD were scored daily starting from day 14 after transfer, when the mice had recovered from irradiation-induced weight loss. (D) Survival plot of mice that received H4/H60-specific T-cell–depleted splenocytes (▪; n = 9) or mock-depleted splenocytes (□; n = 7). (E) Incidence of histopathologic signs of GVHD in the classical target organs.
