In vitro generation of immune effector cells from tumor-associated lymphocytes of human gastric cancer.

Despite recent advances in cellular immunotherapy of cancer, the effectiveness of this type of treatment is limited only to some types of cancer. This study was performed to generate tumor-specific cytotoxic T lymphocytes (CTL) for the treatment of gastric cancer and to find the optimal culture conditions for this CTL, because most immune effector cells used in the previous trials were non-specific killers. Lymphocytes were isolated from tumors, tumor-draining lymph nodes, malignant ascites and peripheral blood of 29 patients with gastric cancer. Lymphocytes from each source were then cultured for three weeks under one or more of the following conditions: 1) 50 U/ml of rIL-2; 2) 50 U/ml of rIL-2 + irradiated (6,000 rad) fresh autologous tumor cells (in vitro sensitization - IVS); 3) 1,000 U/ml of rIL-2; 4) 1,000 U/ml of rIL-2 + IVS. The study found that 1,000 U/ml of rIL-2 generated higher cytotoxicity against allogeneic tumor targets than 50 U/ml of rIL-2 (p < 0.05). However, neither the concentration of rIL-2, lymphocyte source, nor IVS produced any significant differences in cytotoxicity against fresh autologous tumor cell targets. The data suggested that immune effector cells for gastric cancer could be generated efficiently, but it was difficult to produce CTL specific for autologous tumor cells of gastric cancer using a low concentration of rIL-2 and/or in vitro sensitization with autologous irradiated tumor cells.