Immunotherapy of solid tumor by intratumoral infusion of lymphokine-activated killer cells

Fifty million lymphokine-activated killer (LAK) cells were infused into rat T9 gliosarcoma tumors for 1 hr at an infusion rate of 0.1 ml/hr. Cultured normal spleen cells were infused into similar tumors as a control. The LAK cell-treated tumors began to regress at approximately 3 weeks after infusion and disappeared by 6 weeks, while the cultured normal spleen cell-treated tumors grew progressively. Immunohistochemical analysis demonstrated prominent infiltration of cytotoxic/suppressor T cells in the LAK cell-treated tumors, while few lymphocytes were recognized in the control tumors. These data suggested that LAK cells infused intratumorally might be capable of mediating tumor regression by inducing host immunity against the tumor.