ENHANCEMENT OF CYTOTOXIC ACTIVITY OF IMMUNE PERITONEAL LYMPHOCYTIC CELLS AGAINST ANTIGENIC TUMOR CELLS AFTER IN VITRO CULTURE

Abstract

Peritoneal lymphocytic cells obtained from Donryu rats which had been immunized against Yoshida sarcoma cells showed a remarkable cytotoxic effect on tumor cells in vitro. Cytotoxic activity of the lymphocytic cells was enhanced after their incubation for 24-72hr with or without Yoshida sarcoma cells, although the number of cultured lymphocytic cells decreased to one-third to one-fifth and percentage of lymphocytic cells capable of adhering to tumor cells decreased to one-half of the initial count. Continous observation of destructive process of a Yoshida sarcoma cell by adhesion of lymphocytic cells revealed that one precultured lymphocytic cell was able to destroy one tumor cell, although two or more adhering lymphocytic cells were required to destroy one tumor cell unless the lymphocytic cells had been cultured. The fact that cytotoxic activity of some population of immune lymphocytic cells is enhanced after in vitro culture indicates that a part of the mechanism of cell-mediated immune reaction in the present system is associated with a dynamic function of effector lymphocytic cells such as the production of a cytotoxic factor. However, no cytotoxic factor was demonstrable either from the medium in which immune lymphocytic cells were cultured with or without antigenic tumor cells or from the homogenate of cultured lymphocytic cells.