The mTor inhibitor rapamycin delays xenogeneic acute graft versus host disease (aGVHD) in NOD/SCID/IL2rgnull mice (NSG): impact of regulatory T cells

Methods We first assessed the impact of the dose of PBMC infused i.v. on GVHD mortality. After 2Gy irradiation, NSG mice received either 5×105, 1×106, 2×106 or 3×106 human PBMC. We then investigated whether injection of RAPA or PBMC supplemented in Treg could mitigate aGVHD in our model. NSG mice irradiated at 2 Gy TBI were transplanted with 2×106 PBMC and i.p. PBS (control arm), or i.p. RAPA (rapa arm), or with 2×106 PBMC depleted in Treg and i.p. RAPA (Treg-depleted arm), or with 2×106 PBMC supplemented in Treg (1Treg:8PBMC) and i.p. placebo (Treg arm).