Hematopoietic stem cell engraftment

A method of hematopoietic stem cell engraftment in an immunocompetent human patient, the method comprising:

• infusing said human with a human or humanized monoclonal antibody specific for CD117 at a dose of up to 3 mg/kg;
• allowing serum levels of the antibody specific for CD117 to drop to a level of less than 500 ng/ml;
• administering to the patient a cell composition enriched for CD34+ hematopoietic stem cells in a dose of at least 3×105 CD34+ cells/kg;
• wherein sustained levels of blood myeloid chimerism of at least about 1% donor type CD15+ cells is obtained.