Abstract
Sublethally irradiated BALB/c mice innoculated with Moloney sarcoma virus (MSV‐M) develop progressively growing tumors and die within 30 days of virus innoculation. These animals can be protected from tumor progression (and death) by innoculation of small numbers of MSV‐immune T lymphocytes from MSV‐M innoculated (but unirradiated) animals. T lymphocytes in these donor animals have been shown to express immunity to a variety of viral and virallyinduced antigens. We have investigated whether immunity to any one of these antigens was critically important in leading to protection of the irradiated animals by sesitizing normal T lymphocytes in vitro to different viral antigens and examining the ability of these sensitized cells to protect the irradiated recipients. Data is presented to show that cells sensitized in vitro to MSV‐transformed fibroblasts, and to purified antigens with group specificity, but not to viral envelope antigens, or whole virus, are capable of protecting the irradiated MSV innoculated animals.