Augmented immunogenicity of tumor cell membranes produced by surface budding viruses: parameters of optimal...

Membranes prepared from tumor cells infected with surface budding viruses are much more immunogenic than membranes from uninfected tumor cells. Factors affecting immunization with membranes from virus-infected tumor cells were studied. Preparations made with influenza virus were clearly superior to those prepared with vesicular stomatitis virus (VSV). Membranes infected with VSV were maximally immunogenic at a dose equivalent to a 10% cell pack whereas influenza-virus-infected membranes were immunogenic at 1/100th of this dose. Subcutaneous inoculation was better than other routes of administration. Maximum protection against challenge with viable tumor cells was afforded by two inoculations of VSV-infected membranes spaced 3 days apart or a single inoculation with influenza-virus-infected membranes. Administration of membranes in complete Freund's adjuvant either had no effect of induced a slight degree of tumor enhancement. Immunization with influenza-virus-infected membranes significantly reduced tumor size and incidence even at a challenge dose of tumor cells which was 50 times the LD100.