A comparison of the NK cell cytotoxicity with effects of TNF-α against K-562 cells, determined by LDH release assay

Effects of r h TNF-α as a single cytotoxic mediator against K-562 cells was examined by LDH release and compared with NK cell cytotoxicity. The mean values of the percentage of LDH release (x̄=6.25±3.68%, for ten individual experiments) from K-562 cells cultured for 2 h with r h TNF-α 100 U/ml of culture medium did not give significant difference in comparison with mean values of percentage LDH release (x̄=6.43±2.97%, for 37 individual experiments) from K-562 cells which were cultured without r h TNF-α (Studentʹs t-test, P>0.05). The results also showed, that in the presence of increasing concentrations of r h TNF-α there was no significant increase of LDH release through the cell membrane in these short term incubations. However, significant difference in LDH release from K-562 cells was found after 6 h between cultures treated for 30 min with or without r h TNF-α (Mann–Whitney test, P<0.05). Since TNF-α alone shows a lower degree of K-562 cell membrane damage than NK effectors, this suggested that TNF-α is neither an only nor a major mediator of cell destruction, based on determination of LDH release.