2.0 Objectives 
The immune system can provide protection against cancer and 
may play an important role as an adjuvant treatment for 
malignancy. Lymphokine activated killer cells (LAK) and tumor 
infiltrating lymphocytes (TIL) can lyse neoplastic cells and 
produce partial or complete tumor rejection. Expression of 
cytokine genes in malignant cells has also enhanced tumor 
regression. Because current strategies to stimulate an immune 
response against tumor cells often fail to eradicate tumors, an 
important goal of immunotherapy is to improve upon current 
techniques and understand the mechanisms of immune recognition. 
In this study, we attempt to improve upon our previous 
studies to enhance the immune response against tumors. We have 
utilized direct gene transfer into tumor cells in vivo as a 
method to simplify the delivery of genes in vivo. Traditionally, 
gene transfer techniques have focused on modification of tumor 
cells in vitro, followed by transfer of modified cells. Such 
approaches subject these cells to selection and different growth 
conditions from those which act in vivo. Because they also 
require that cell lines be established for each malignancy, 
adaptability to human disease is more difficult and requires more 
time. 
We have previously described a model for the immunotherapy 
of malignancy using a gene encoding a transplantation antigen, an 
allogeneic class I major histocompatibility complex (MHC) 
antigen, introduced into human tumors in vivo by DNA/ liposome 
transfection (1,2). Expression of allogeneic MHC antigens on 
Recombinant DNA Research, Volume 17 
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