Allogeneic haematopoietic stem-cell transplantation was introduced in clinics to reconstitute immune system of severely damaged patients from bone marrow toxicities caused by high-dose chemo-radio therapy. However, immune competent T cells in the grafts can react against recipient MHC-peptide complexes, leading to graft-versus-host disease (GVHD) in the skin, gastrointestinal tract and liver, a life threatening complication. The highest risk factor of GVHD is mis-match on MHC (HLA) locus between donors and recipients.

Even though the transplantation of stem-cells from identical MHC (HLA) donors is more frequently performed by virtue of stem-cell banking organization, GVHD risks still exist, because of recognition of minor histocompatibility antigens presented to donor-originated T cells. In our laboratory, CD8 T cell responses during GVHD caused after MHC-matched grafting are under investigation. Our goal is to characterize the biology of CD8 T cell response, molecular mechanism of T cell migration to the target organs, and cellular interaction between CD4 and CD8 T cells and/or between adaptive and innate immune cells, so as to develop the strategies to relieve the risks of GVHD.