direct gene transfer of specific recombinant genes could elicit 
an immune response to the product of that gene in vivo (19). 
These studies suggested that the introduction of the 
appropriate recombinant genes could be used to stimulate the 
immune system to recognize its product in vivo. In addition, 
this approach provided a general method for the induction of a 
specific site in vivo. To determine whether direct gene transfer 
might be appropriate for the treatment of disease, a murine model 
of malignancy has been developed. Direct gene transfer of an 
allogeneic histocompatibility complex gene into a murine tumor 
elicits an immune response not only to the foreign MHC gene but 
also to previously unrecognized tumor-associated antigens. These 
immune responses are T cell-dependent, and these tumor-associated 
proteins are recognized within the context of the self major 
histocompatibility complex. In animals presensitized to a 
specific MHC haplotype, direct gene transfer into established 
tumors could attenuate tumor growth or, in some cases, lead to 
complete tumor regression (5) . These studies demonstrate that 
direct gene transfer of foreign MHC genes into tumors have 
potentially therapeutic effects that may be appropriate for the 
treatment of malignancy. 
1.4 Immunotherapy of Malignancy. 
In some instances, the immune system appears to contribute 
to the surveillance and destruction of neoplastic cells, either 
by mobilization of cellular and humoral immune effectors. 
Cellular mediators of anti-tumor activity include MHC-restr icted 
cytotoxic T cells, natural killer (NK) cells (23,24) and 
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