Inhibitory effect of K-562 malignant cells on locomotion of human neutrophils

Certain tumor cells generate factors that inhibit neutrophil chemotaxis. The present study was designed to explore, in K-562 malignant cells, the release of such factors that may alter the neutrophil locomotion. The supernatant, separated from the K-562 malignant cells cultured in vitro for 48 hours, was lyophilised and extracted with ethanol 80%. This ethanol extract (SE-K562) inhibited neutrophil locomotion. Both random and locomotion induced either by formyl-methionyl-leucyl-phenylalanine (FMLP) or serum were inhibited. SE-K562 was partially purified by Sephadex chromatography and the analysis of the eluted active fraction by SDS electrophoresis led one band of about 8 kd. No one inhibitory effect was observed with appropriate controls. In conclusion, K562 malignant cells in culture release a low molecular weight factor (8 kd) that inhibits all forms of PMN locomotion i.e. random locomotion and locomotion induced either by FMLP or serum.