Specific Immune of a Syngeneic Response Against Tumor-Associated Simian Virus 40-Induced Sarcoma in Antigens Mice

Abstract

Immune response against syngeneic simian virus 40 (SV40)-induced tumor-associated antigens in (BALB/c × C57BL/6)F₁ female mice was detected by in vivo tumor challenge and an In vivo tumor cell neutralization test (Winn) and by the In vitro ⁵¹Cr-release cytotoxicity assay. All mice Immunized with as low as 1×10⁵ SV40-transformed cells were protected against the growth of SV40-lnduced tumor, beginning at 3 days and up to 90 days after a single immunization. In the tumor cell neutralization test, spleen cells (T-cells) from mice immunized with 1×10⁸ SV40-transformed cells prevented tumor growth at 10 days and up to 90 days after immunization. The specificity of the Immune response was shown by the use of unrelated syngeneic tumor cells in crisscross experiments. In contrast to these in vivo assays, spleen cells from mice Immunized with a minimum of 20×10⁸ SV40-transformed cells were cytotoxic in vitro against the relevant target cells in a 4-hour ⁵¹Cr-release cytotoxicity assay. Cytotoxic lymphocytes were detected 3 days after immunization, reached peak activity at 8 days, and declined to low levels at 14 days after immunization. At all points after immunization, T-cells were needed for cytotoxic reactivity to be eliminated by specific anti-θ serum and complement. The specificity of the cytotoxic reactivity was shown by the use of unrelated syngeneic tumor cells in crisscross experlments.