Basic evaluation of lymphokine activated killer (LAK) therapy, effects of concomitant use of biological response modifier (BRM) and recombinant interleukin 2 (rIL-2)

Abstract

The success in LAK therapy depends on obtaining a large amount of cells with high LAK activity. We considered that the absolute number of cells in culture is not the number of true LAK cells but that ³H-thymidine uptake by cells that react to rIL-2 is a mark of true LAK cells. We assumed that high LAK activity and the greatest ³H-thymidine uptake are the conditions to obtain a large amount of high LAK activity cells and examined this hypothesis. We also examined the enhancement of induction of the LAK activity by the addition of Nocardia rubra cell wall skeleton (N-CWS) and rIL-2 to the culture.
The optimal condition to obtain a large amount of high LAK activity cells was culturing 2.5×10⁶/ml lymphocytes for 5 days with 2 U/ml or more rIL-2 in the presence of human type AB serum. No LAK activity was induced by culturing with N-CWS alone, but the LAK activity was markedly enhanced by culturing with N-CWS and rIL-2. The LAK activity was enhanced by adding rIL-2 first and N-CWS next after 2 days, but no LAK activity was induced by adding N-CWS first and then rIL-2 2 days later.