Lymphocytes that mediate systemic resistance to in vivo growth of a carcinogen-induced syngeneic tumor.

Wistar rats immunized with irradiated syngeneic methylcholanthrene-induced sarcoma, Mc7, are able to suppress a subsequent challenge of this tumor. Cells obtained from thoracic-duct lymph of these tumor-immunized animals and infused intravenously into normal syngeneic rats transfer specific tumor resistance to the recipients. These mediators of tumor resistance have the characteristics of T lymphocytes that are in a nonproliferating state and have an effective life span at least 2 weeks in normal recipient rats.