In a Phase I study, recombinant interleukin-2 (IL-2) or autochthohous lymphokine-activated killer (LAK) cells were used to treat nine patients with malignant glioma. One patient received the combination of IL-2 and LAK cells. LAK cells were generated by culturing IL-2 with peripheral blood lymphocytes obtained from brain tumor patients. Escalating doses of LAK cells (10(8)-10(10) or recombinant IL-2 (10(4)-10(6) units) were administered by direct injection into the brain tissue surrounding the cavity left following operative tumor removal. There have been no signs of systemic or neurotoxicity following treatment. The tumor selective killing of the LAK cells used for these treatments was demonstrated by their ability to lyse glioma cells but not normal cells in vitro using a chromium release microcytotoxicity assay.