Cytotoxicity of human rosette‐forming blood lymphocytes on cultivated human tumor cells

Human peripheral blood lymphocytes from seven cancer patients were separated into two fractions, one rich in lymphocytes which could spontaneously form rosettes with sheep erythrocytes (T‐cells) and another poor in rosette‐forming cells. These two fractions were then tested for cytotoxic activity on cultivated tumor cells of the same histological type as the tumors of the respective lymphocyte donors. It was shown that T‐cell rich fractions had a higher cytotoxic activity than did the T‐cell poor fractions from the same patients. The findings indicate that human T‐cells can be cytotoxic, in vitro, against cultivated cells carrying tumor‐associated antigens.