[Experimental studies on induction of various lymphokine-activated killer cells using recombinant interleukin 2]

Fundamental studies were performed on adoptive immunotherapy, especially on promotion of cell proliferation and on augmentation of cytotoxicity of various lymphokine-activated killer cells, induced by recombinant interleukin 2(R-IL2) with (P-LAK) or without (LAK) PHA, from peripheral blood lymphocytes (PBL) of healthy volunteers. The following results were obtained. 1) In LAK induced by culturing normal PBL with R-IL2, a cell proliferation was observed in 14 days. Their cytotoxic activity against all the strain cells examined, was higher than PBL already on the third day of culture. 2) Culturing normal PBL with PHA (with or without R-IL2) for 3 days, followed by culturing with R-IL2 for 11 days, caused a marked increase in cell number by about 65 times in 14 days. Cytotoxicity of these cells against MKN-28, MKN-45 and KATO III was found to increase with lapse of culture time. 3) On the 14th day of culture, cytotoxicity of LAK was higher than that of P-LAK. 4) Surface phenotype analysis of LAK revealed that OKT3+ (cell ratio) tended to increase, OKT8+ increased significantly, OKT4+ and Leu7+ tended to decrease, and OKT4+/OKT8+ ratio decreased significantly. Analysis of P-LAK revealed that OKT3+ and OKT8+ increased significantly and OKT4+, Leu7+, and OKT4+/OKT8+ ratio decreased significantly. 5) The rate of total increase in cytotoxicity, calculated in multiplying the rate of cell number increase by the rate of increase in cytotoxicity, was higher in P-LAK than in LAK. The above results showed that P-LAK induced by addition of PHA for the first few days, could cause marked increase both in cell number and in total cytotoxicity.