Simian virus 40 (SV40)-induced
sarcomas and adenovirus 7-induced
sarcomas (Adv-7) exhibit both specific
tumor-specific
transplantation antigens (
TSTA) and cross-protective embryonic
antigens at the cell surface in the LAK:LVG(SYR) strain of Syrian golden hamsters. Specific SV40
TSTA could be released from the surfaces of living hamster
sarcoma cells in a 2.5% crude
1-butanol extract (CBE) and served as immunogen to protect syngeneic recipients against subsequent homologous but not heterologous
tumor cell challenge. The CBE-extracted SV40-induced
TSTA (
tumor-specific) was observed to be free of detectable, cross-protective embryonic
antigens (EA) by
tumor transplantation assays. The induction of cytotoxic lymphocyte-mediated immunity with the CBE-released
TSTA was dependent on the administration of a single sensitizing injection of 12-20 micrograms
antigen protein. Higher concentrations (50-1,000 micrograms) of the CBE
tumor cell extract, given in a single injection, enhanced
tumor growth as did two
injections of 12.5 micrograms CBE-extracted SV40-induced
TSTA at 1-week intervals. A cross-protective
antigen(s), not detected in the CBE
tumor extracts, was retained in the intact, 1-butanol-extracted SV40 and Adv-7-induced tumor cell lines after completion of the CBE extraction procedure and in similarly extracted 10-day hamster fetal cells. Some alterations in the normal immunogenicity of EA extracted with CBE followed by KCI from SV40-induced
sarcoma cells could be detected in the
transplantation assays and lymphocyte transformation assays, whereas EA extracted from CBE-KCI-treated Adv-7 cells or 10-day hamster fetal cells retained normal immunogenicity in vivo and in vitro. These procedures provide a means for successful separation of immunogenic SV40- and Adv-7-induced
TSTA from detectable, biologically active, cross-protective EA from the surfaces of these
sarcoma cells.