Previous studies have demonstrated that G-CSF has immunomodulatory effects and can suppress T lymphocytes [62].Such effects are probably important in allotransplant recipients receiving peripheral blood stem cell grafts because the frequency of GVHD is similar for bone marrow and mobilized peripheral blood stem cell grafts even though a higher frequency would be expected for the blood grafts due to their larger number of T cells in these grafts [62]. This evidence concerns the gene CSF3 and graft versus host disease.