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, a novel approach to enhance the immune 
response against tumors will be explored by the introduction of 
recombinant genes directly into tumor cells 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. 
We have developed a model for the immunotherapy of 
malignancy using a gene encoding a transplantation antigen, an 
allogeneic class I major histocompatibility complex (MHC) 
antigen, which will be introduced into human tumors in vivo by 
DNA/liposome transfection. In animal studies, we find that the 
expression of allogeneic MHC antigens on tumor cells stimulates 
immunity against both the allogeneic MHC gene on transduced cells 
[402] 
Recombinant DNA Research, Volume 15 
