FASLG and graft versus host disease: As a prelude to the clinical use of FasL to prevent GvHD in patients undergoing stem cell transplantation, we have explored the effects of a brief (2 h) incubation of MPBCs derived from healthy, adult donors with FasL on graft composition (T cell subsets, antigen-presenting cells, in vitro hematopoietic colony formation and CD34+ hematopoietic progenitor cells).