A method has been developed for isolating and growing lymphoid cells infiltrating murine solid tumors. When tumor cell suspensions are placed in T cell growth factor (TCGF) lymphoid cells and not tumor cells proliferate. By 7 to 9 days lymphoid cells free of tumor can be harvested and grown continuously in TCGF. The growth of these cells is dependent on the presence of TCGF but not on the presence of concanavalin-A. Tumor cell suspensions that have been freed of T lymphoid cells by treatment with anti-Thy-1.2 serum and complement or by fractionation on Ficoll gradients exhibit no cell out-growth in TCGF. The lymphoid cells growing in TCGF exhibit significant cytotoxicity for syngeneic tumor cells and normal fibroblasts grown in culture but do no lyse normal lymphoid cells.
