The main goal of this study is to develop and improve the method of processing cells that are collected after stimulation with growth factor (G-CSF), by removing the white blood cell lymphocytes which can cause graft-versus-host disease (GVHD) while keeping the stem cells necessary for healthy blood cell building. In addition, researchers are interested in studying whether giving G-CSF has an effect on lymphocyte function, which may influence the immune reactions occurring in bone marrow transplantation.