In vitro cytotoxic effect of guinea-pig natural killer cells (Kurloff cells) on homologous leukemic cells (L2C).

The Kurloff cell (KC) of the guinea-pig develops natural killer cytotoxic activity in heterologous systems. We report in this paper the effective in vitro cytotoxic activity of the KC in a homologous guinea-pig system, i.e. against the guinea-pig target leukemic L2C cells. A dual-color flow analysis of homologous effector-target conjugates, using calcein-labeled KC and hydroethidine-labeled L2C shows a 40% frequency KC-L2C conjugation. The specific cytotoxicity of KC against L2C (78%) was estimated as the target-loss of green fluorescence due to hydrolysed carboxy-fluorescein diacetate after 4 hours at 37 degrees C. We propose that the Kurloff cell could be involved in surveillance against spontaneously arising leukemic cells, and this could be an explanation for the high degree of resistance to spontaneous or experimentally-induced cancers, in the guinea-pig.