amphotropic packaging line PA317 (61), which was the same packaging cell line used in the 
N2/TIL human protocol. These producer lines have remained helper virus free for several 
months of continuous culture. We have recently rederived a helper free SAX- producer line and 
during the course of the formal evaluation of this protocol we will continue to test this and other 
vectors to determine the most efficacious vector for clinical use. The Food and Drug 
Administration will evaluate the data and approve the vector ultimately selected for this 
protocol. 
The LASN modified ADA(-) T cells were shown to express normal amounts of hADA, to express 
neomycin phosphotransferase, and to be resistant to the toxic effects of deoxyadenosine in 
culture. On average, the ADA(-)T cells were transduced at about the same frequency as we have 
achieved with the N2/TIL protocol using the LNL6 vector. The transduced cells were further 
evaluated for cell surface phenotype, helper cell activity for immunoglobulin production and 
for their intrinsic cytolytic characteristics. For example, these cells did retain some helper T 
cell function which augmented immunoglobulin production by normal B cells in culture. 
Importantly, the ADA gene-corrected patient T cells continued to proliferate in culture and 
survived much longer than the T cells which had not been corrected by ADA gene insertion. This 
data suggests that intracellular ADA may confer a survival advantage to ADA(-)T cells even in 
an environment lacking exogenous deoxyadenosine. See Appendix 13.2, Figures 1-6. 
1 .5 In Vivo Survival and Gene Expression of Retroviral Vector Modified T cells in Mice, 
Rhesus Monkeys and Man 
We have demonstrated in mice, Rhesus monkeys and man that T-cells grown in vitro can be 
readily transduced with retroviral vectors and will sun/ive and express the introduced genes 
for substantial time periods in vivo after reinjection. In the mouse, experiments with Sperm 
Whale Myoglobin-specific (SWM) T-helper cells have also demonstrated that IL2 expanded and 
gene transduced T-cells maintain their ability to function as T-helper cells for antibody 
production in vivo. In our experiments with human tumor infiltrating lymphocytes (TIL) 
transduced with the neoR gene, we have recovered vector containing T cells as long as 6 months 
after initial cell transfer and have observed no untoward effects of any kind associated with the 
transferred gene. Our colleague, Claudio Bordignon, has shown that PBL from ADA(-)SCID 
patients transduced with the hADA gene survive and function normally when transplanted into 
immunodeficient BNX mice while. non-transduced ADA(-) PBL do not. (67) 
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Recombinant DNA Research, Volume 14 
