Defining a therapeutic dose of peripheral blood stem cells.

Peripheral blood stem cells (PBSC) are now used extensively to provide rapid and durable hematopoietic reconstitution following supralethal myeloablative therapies. A major clinical issue is the quantitation of the cells responsible for reconstitution. We review here published reports of transplants using the measurement of mononuclear cells and granulocyte-macrophage colony-forming units (CFU-GM) to quantitate PBSC. In addition, we present data from three institutions where hematopoietic recovery is correlated with doses of CFU-GM or CD34+ cells. These data suggest doses of 20 x 10(4) CFU-GM or 2 x 10(6) CD34+ cells/kg body weight that provide rapid engraftment of neutrophils and platelets.