Analysis of parameters for maximal in vitro proliferation and activation of lymphokine-activated killer cells (LAK)

In 15 patients (11 adults, 4 children) who received IL-2 and LAK cell therapy, we analyzed the different culture conditions which could either improve LAK cell activation and proliferation or which could simplify the procedure. Each parameter was assayed on a large scale and compared to standard culture conditions. Indomethacin had no effects, either positive or negative, on proliferation and activation of the cells. Culturing with 10% AB serum increased proliferation but did not modify total lytic activity compared to 2% AB serum. When cells were cultured in a medium with 2% autologous plasma obtained before any treatment, their proliferation was similar to that obtained in medium supplemented with 2% AB serum but the LAK activity was significantly higher. Autologous plasma obtained at day 8 of treatment (48 h after the first cycle of IL-2 and the day of the first cytapheresis) gave similar results to 2% AB serum. None of the 12 patients showed negative effects suggesting the presence of suppressive factors in the sera. Culturing with autologous plasma in clinical trials will lead to a 25% decrease in the total cost of culture and suppress the risk of viral contamination. Excess of granulocytes in the culture (greater than 30%), if the total nuclear cell concentration did not exceed 3 . 10(6) per ml, induced a better proliferation of mononuclear cells without modification of the activation. These results could be due to the liberation of factors by polynuclear cells, or to the loss during elimination of the granulocytes by the Ficoll separation of cells with similar density supporting LAK activity.