recovered from lymph node biopsies contained the gene marker 
whereas the peripheral blood was negative for gene expression. 
Dr. Blaese then discussed the safety issues related to the TIL 
experiments. He said one question raised by the Human Gene 
Therapy Subcommittee had to do with the presence of infectious 
helper virus or replication competent retrovirus in the 
population of cells as well as in the vector that is to be 
introduced. Dr. Blaese said although he believed there was no 
evidence that infectious helper virus is present either in the 
initial population or in the TIL populations that will be given 
back to the patients, their presence can be tested; and that 
infectious virus will not be given back to patients. 
Dr. Blaese said another question related to whether introducing 
the gene into TIL would change their characteristics or induce 
some transformation event that would make their growth 
characteristics different from normal TIL. He presented data on 
the proliferation of TIL populations over time, measuring counts 
per minute of thymidine incorporation, with or without IL-2. In 
the presence of IL-2, marked TIL proliferated well but did not 
proliferate if IL-2 was removed, demonstrating the absence of 
autonomously growing cells in these cultures. Furthermore, they 
inserted vectors into TIL in culture, and found that in the 
absence of IL-2, no viable cells could be detected after 2-3 
weeks, showing that no transformation event had been induced that 
might result in IL-2 independent cells. 
Dr. Mulligan asked how many mice had been tested in the murine 
experiment. Dr. Blaese said six animals were used in the first 
experiment. Further, there was a second series of experiments 
with mouse TIL that wasn't shown, using a similar protocol where 
lymphoid, lung, spleen, kidney, and liver tissues were recovered 
at 1 hour, 6 hours, 26 hours, 72 hours, 5 days, 7 days, 9 days, 
and 11 days after transfer of TIL. In this experiment, the 
strongest signals obtained so far have been in the lung at 1 and 
6 hours and in the liver at 24 hours. 
Dr. Kelley asked if there were other species where TIL had been 
demonstrated that might serve as a model for man. Dr. Rosenberg 
replied that it had only been done in mouse and man, but that TIL 
from spontaneous cancers in other species could be looked at. 
Dr. McGarrity announced the morning coffee break, and then 
resumed discussion with Dr. Anderson's presentation. 
Dr. McGarrity reiterated the tabs relevant to the agenda item and 
asked Dr. Anderson to continue. 
Dr. Anderson noted that questioning had been vigorous and that 
members of the Human Gene Therapy Subcommittee, some of whom are 
his closest competitors, also had scrutinized the protocol at 
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