Human Gene Therapy Subcommittee - 7/30/90 
stating that a specific limitation of the model is that he could 
not generate a primary or secondary response to tetanus toxoid 
antigens even when using a huge number of peripheral blood 
lymphocytes with a complete repertoire. It is beyond the 
capability of this model to address whether or not a primary 
response is obtainable to an antigen to which the patient has not 
been exposed. 
Dr. Bordignon said the model he used for the experiment was to 
take an immune deficient mouse (NIH-3 or BNX mouse) and 
reconstitute the mouse's immune system with human peripheral 
blood lymphocytes (PBLs) . He said that his data confirm the 
survival and function of human T and B cells since human IgG can 
be identified in the peripheral blood of the mice after 
reconstitution. He then modified this model by using ADA- 
deficient human PBL which had been made ADA-positive by 
utilization of a vector and transduction and made immunocompetent 
by PEG-ADA. He looked for the presence of vector DNA, and thus 
vector-derived ADA, in the peripheral blood of the mice. 
Dr. Bordignon said that a single patient was used for all sets of 
the experiments, studying at most 2 mice per month, since only 
20-30 million cells could be extracted from the patient monthly. 
He noted that serum ADA level of the patient remained constant 
throughout the study and was efficacious in detoxifying the 
environment of the patient. 
Dr. Bordignon said that total lymphocytes and all the subsets of 
T cells were normal in the patient. The patient maintained a 
normal CD4/CD8 ratio with normal T cell responses after PEG-ADA 
treatment. The patient's immune function was analyzed by 
response to several different antigens both in vitro and in vivo 
and showed the patient's T cells were functional. He said that 
immunoglobulin (Ig) response to vaccination went from nothing 
before treatment to the normal range and then declined. After a 
second boost the level went back up and remains normal. 
Dr. Bordignon said that the vector used was produced by Petros 
Hantzopoulos in the laboratory of Eli Gilboa. It is the only 
vector used in the mice; therefore, he could not make any 
comparison to other vectors in this model. This vector proved to 
be most suitable by its frequency of infection and level of 
expression at the single cell level. He said that the model was 
analyzed by whether or not human IgG was present in the PBLs of 
mice and that the results were clear and reproducible. If the 
animals were untreated, they had no human IgG in peripheral 
blood. If they were treated with ADA-deficient human PBLs, there 
was very little IgG found, and after 2-3 weeks it was not 
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Recombinant DNA Research, Volume 14 
