As shown in Table IV, we then examined how the ratio of marked 
blasts to unmarked cells would change as one varied the percentage l 
of leukemic blasts in the marrow from 1/100 to 1/10®. The ratio of j 
one leukemic blast to 100 mature cells is the maximum ratio present i 
following the chemotherapy used to generate a second chronic phase j 
in CML blast crisis patients before bone marrow storage. The ratio ] 
of 1/100 is the upper limit of blasts/mature cells possible ; 
(beneath the level of detection by Southern or morphology) in a j 
marrow morphologically said to be in second chronic phase | 
(morphology or Southern is not sensitive to leukemic blasts present \ 
at ratios lower than 1/100) . As shown in Table IV, there would be ' 
a maximum of 1,200,000 virally-marked marrow leukemic blasts and | 
6,000,000 virally-marked peripheral blood leukemic blasts in the : 
transplant infused into such patients. ^ 
f; 
The question is how much lower could the ratio of leukemic [ 
blasts/chronic phase cells be driven downward by chemotherapy. As 
shown in Table IV, the level of NEO marked leukemic blasts present 
in autologous marrow and peripheral blood at storage, in which the 
ratio of blasts/ chronic phase cells had been lowered to 1/10,000, ^ 
would be 12,000 for marrow and 60,000 for peripheral blood. This | 
latter figure is clearly sufficient for detection of NEO positive 
cells at the time of storage (1 NEO positive cell/300,000) by PCR. ' 
/ 
f 
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Recombinant DNA Research, Volume 14 
