Specific immunoprophylaxis in experimental tumour-host systems.

A variety of animal species have been rendered resistant to syngeneic tumours of many histologic types of immunoprophylaxis. Among the types of preparation of tumour-associated antigens that have merit as vaccines are tumour cells treated with radiation, mitomycin C, certain viruses, neuraminidase, sulfhydryl blocking agents and lipoidal reagents. Alternatively, tumour-associated antigens of the cell membrane may be solubilized and used for vaccination. Recent studies with dimethyldioctadecylammonium bromide (DDA) indicate that it both modifies tumour cells and serves as an immunologic adjuvant in that it enhances protective responses to iodoacetamide-treated lymphoma cells and acts as a potent macrophage activator. By judicious application of DDA either delayed hypersensitivity or antibody response may be selectively enhanced. Several advantages of DDA over other adjuvants are its water solubility, the fact that it does not produce deleterious lesions at the site of injection and the fact that it eliminates the risk of systemic infection that exists with the use of live bacteria.