counts < 8.0 X 10 9 /L. A median of 7 (range 6 - 17) apheresis procedures were required 
for these patients. The total collection for each patient contained a median of 3.62 
(range .68 - 57.67) X 10 4 CFU-GM/ kg. Twenty-nine patients have been transplanted 
without post-transplant cytokines. The median time to reach 0.5 X 10 9 /L granulocytes 
after transplant was 23 days (range 13 - 49) for 28 evaluable patients. Median time to 
reach platelet transfusion independence was 23 days (range, 7 - 67) for 23 evaluable 
patients. The authors concluded that GM-CSF reduced the number of required apheresis 
procedures but did not provide for a quicker marrow recovery than unstimulated PBSC’s. 
The maximum follow-up of this group of patients is 10 months and there has been no 
evidence of late graft failure (A. Kessenger, personal communication). 
Haas and colleagues administered GM-CSF (at 250 ng/ m 2 /d as a continuous infusion) to 
11 patients for a median of 11.5 days (range, 5-22) followed by a median of 6 apheresis 
procedures (35). Leukapheresis was started at a WBC of > 10 X 10 9 /L and the dosage 
of rhGM-CSF was adjusted to keep the WBC between 10 X 10 9 /L and 20 X 10 9 /L. The 
median number of mononuclear cells collected was 5.15 X 10 9 (range 2.8 - 9.9) and the 
median number of CFU-GM’s collected was 30.1 X 10 4 (range 10.2 - 1693). The median 
increase of CFU-GM’s in the blood was 8.5 fold. Six of these 12 patients were treated 
with high-dose chemotherapy and/or TBI followed by infusion of PBSC’s. Five of 6 
achieved sustained engraftment but the follow-up was less than 6 months. 
F. Animal Data Supporting the Concept that Long-Term Marrow Repopulation can be 
Achieved with G-CSF Exposed PBSC’s. 
The question of whether G-CSF mobilized peripheral blood can contribute to long-term 
engraftment has been addressed in mice by Molineux et al (41). They pretreated mice 
with human G-CSF and transplanted PBSC’s into recipients of the opposite sex. Using a 
molecular probe for the Y chromosome they were able to show that among peripheral 
blood cells mobilized by G-CSF there were substantial numbers of primitive stem cells 
capable of (1) reconstituting the hematopoietic system in the long term and (2) making a 
contribution to the lymphoid populations of the thymus in irradiated recipients. 
G. Summary of Seattle Experience with Growth Factor Stimulated PBSC’s. 
(1) Large Animal Data 
Two dogs were given canine G-CSF and peripheral blood progenitors measured. 
The results of these studies are shown in table . 
Recombinant DNA Research, Volume 16 
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