immunotherapy [47], 
The introduction of genes into T lymphocytes as a means of improving in vivo 
efficacy following cell transfer has also been explored. TIL have been transduced 
with a retrovirus encoding the gene for tumor necrosis factor (TNF) constitutively 
expressed under the transcriptional control of the retroviral long terminal repeat 
(LTR) [48]. These functionally modified TEL have been administered to patients with 
advanced cancer with the goal of providing a greater antitumor effect. Although no 
acute toxicities were observed in die initial patients treated, a limitation of this 
approach is that if toxicity occurs due to the infused genetically modified T cells, 
there is no readily available method of specifically ablating these cells. Thus, for 
studies of adoptive immunotherapy with genetically modified T cells, it would be 
desirable to have a means of eradicating transferred T cells should toxicity occur. 
Gene transfer has also been used as an approach to treating children with severe 
combined immunodeficiency (SCID) who have a deficiency of the enzyme adenosine 
deaminase (ADA). Patients have been treated with autologous T lymphocytes 
transduced with a retroviral vector encoding the ADA gene in an attempt to 
permanently correct the patient’s ADA deficiency. Although the follow up is short 
and detailed clinical information has not been reported, no acute side effects due to 
the administration of these genetically modified T cells were observed. 
3. Adoptive immunotherapy with CD8+ CMV-specific T c clones following allogeneic 
BMT 
Studies in our laboratory have demonstrated that the reconstitution of CMV-specific T 
cell responses following allogeneic BMT correlates with protection from developing 
severe CMV disease [49]. Therefore, using in vitro culture techniques to isolate and 
propagate CD8 + CMV-specific T c clones [50, 51], we have initiated a Phase I study 
to evaluate the safety of adoptively transferring donor-derived CD8 + CMV-specific 
cytotoxic T cell clones to the respective BMT recipient and to determine the potential 
of this approach for reconstituting CMV-specific immunity. Five patients have been 
treated with four weekly escalating doses of CD8 + CMV-specific T c clones beginning 
days 28 to 42 posttransplant. No alterations in vital signs or oximetry were observed 
during and immediately following the twenty cell infusions. One patient developed a 
transient low grade fever four hours following the fourth dose of T cells (cell dose 1.0 
x 10 9 /m 2 ). Blood cultures were negative and the patient defervesced in less than 
twelve hours without antimicrobial therapy. None of the five patients developed new 
onset or worsening of acute graft versus host disease following cell transfer. Thus, 
adoptive immunotherapy with up to 1.4 x 10 9 CMV-specific T c /m 2 appears to be safe 
and nontoxic in allogeneic BMT recipients. 
The patients treated with CD8 + CMV-specific T c have been followed to determine the 
efficacy of T cell transfer in reconstituting immunity to CMV. Three of the five 
patients had undetectable CMV-specific CD8 + T c and CD4 + T H responses in 
peripheral blood immediately prior to T cell transfer, and all three had detectable 
CD8 + T c responses but not CD4 + T H responses 48 hours following the first cell 
infusion (cell dose 3.3 x 10 7 /m 2 ). Moreover, the CD8 + T c responses persisted prior 
[614] 
Recombinant DNA Research, Volume 15 
