B) To evaluate the in vivo survival of culture-expanded autologous T cells and the duration of 
expression of the inserted genes. 
3.0 Selection of Patients 
Children with documented SCID secondary to ADA deficiency. All patients to be treated by gene 
transfer under this protocol will be concurrently treated with PEG-ADA unless they have 
become refractory or allergic to this drug. The decision to treat with PEG-ADA rather than 
bone marrow transplantation will have been made by the patient’s parents and the child’s 
physician independent of input by the NIH investigators and prior to consideration for 
enrollment in this protocol. Those patients receiving PEG-ADA will have been treated with at 
least 15 U/kg for a minimum of 9 months before enrollment. This is to permit evaluation of 
the extent of immune reconstitution achieved with PEG-ADA alone. To be eligible for 
enrollment, the initial patients must have objective evidence of incomplete reconstitution 
despite PEG-ADA treatment. These objective measures are listed below. Persistent or 
recurrent thrush will also be considered evidence of deficient T cell function. 
Chronic pulmonary and gastrointestinal infections are common in these patients. Children with 
significant pulmonary disability defined as hypoxia at rest (<91% 02 saturation) will not be 
enrolled in part 2.B. of this protocol until sufficient experience has been obtained with 
lymphocyte infusions in children with ADA(-) SCID to be comfortable that the infusion of large 
numbers of cells will not expose the patient to unacceptable risk. Children with acute hepatitis 
or those with chronic liver disease resulting in significantly impaired liver function will also 
be deferred from Part 2.B. until the tolerance of this procedure is established in children with 
more normal hepatic function. Treatment of children currently experiencing acute infections 
will be postponed until satisfactory infection control has been accomplished. HIV screening 
will be performed by the referring physician and children with HIV infection will not be 
accepted for this study. Confirmatory non-seroiogic studies for HIV status will be performed at 
the NIH. Children with HIV infection will be excluded. Patients with malignancy will not be 
accepted. 
Immunologic Inclusion Criteria :" the patients must manifest any three of the following 
immunologic features to the eligible for inclusion in this protocol. 
Recombinant DNA Research, Volume 14 
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