[The in vitro antitumor effectiveness of murine lymphokine-activated killer (LAK) cells induced by recombinant IL-2].

We have studied the in vitro antitumor effectiveness of murine lymphokine-activated killer (LAK) cells induced by recombinant IL-2 (rIL-2). LAK cells were generated by placing 5 X 10(7) fresh C 57 BL/6 splenocytes (erythrocytes were lysed osmotically) in 10-cm (diameter) dishes (Falcon) containing 10 ml of complete medium (CM). The CM consisted of RPMI 1640 with 0.1 mM non-essential amino acids, 1 microM sodium pyruvate, 5 X 10(-5)M 2-mercaptoethanol, 50 micrograms/ml gentamicin sulfate, 0.03% glutamine, 10% heat-inactivated fetal calf serum (FCS) and 10 units/ml of rIL-2 (TGP-3, provided by TAKEDA Chemical Industries, Ltd). The dishes were incubated horizontally at 37 degrees C in a 5% CO2 atmosphere for 72-96 hr. The LAK cells were then harvested, washed three times, and resuspended in RPMI 1640 with 5% heat-inactivated FCS for the in vitro cytotoxicity assay. The antitumor cytotoxic activity of LAK cells was estimated in triplicate by 4 hr 51Cr release assays. The cytotoxic activity of LAK cells against syngeneic 203 glioma and normal syngeneic glioblasts was approximately 50% and a few %, respectively. The in vitro cytotoxicity of LAK cells against syngeneic EL-4 thymoma, allogeneic YAC-1 lymphoma and P-815 mastocytoma was 72%, 87% and 43%, respectively. Thus LAK cells have apparent tumor specificity in vitro and are easily generated. Fresh splenocytes of CBA/J mice were markedly lytic for natural killer (NK)-sensitive YAC-1 cells, but not for 203-glioma cells or NK-resistant P-815 cells.(ABSTRACT TRUNCATED AT 250 WORDS)