Differential Extraction of Tumor-Specific Transplantation Antigen and Embryonic Antigen From Simian Virus 40-and Adenovirus 7-Induced Sarcoma Cells of Hamsters With 1-Butanol and 3 M Potassium Chloride2

Abstract

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.